Korte aantekeningen over allerlei onderwerpen

Een ongewone doodsoorzaak van een Stigmella-larve: een “pseudo-Bucculatrix“-mijn

Hoe steekt Lyonetia clerkella een dikke nerf over?

Tabel voor de gras-bewonende Agromyza-larven

Tabel voor de subgenera van het geslacht Cerodontha (Agromyzidae)

De cocon van Bucculatrix

Overproductie van eieren bij Ectoedemia albifasciella

De ontwikkeling van de agame generatie van de knoppergal

Tabel tot de soortengroepen binnen het grote geslacht Euura

gallers on Campanula

pub 11.xii.2019

Dichotomous table for gallers on Campanula

by Hans Roskam

1a On parts above ground => 3

1b On roots or rhizomes => 2

2a Reddish, spongy bud gall on rhizome, up to 4 mm long. Contains an orange-yellow larva. C. rotundifolia: Unidentified gall midge

b Main- and side roots with many small swellings, similar to bacterium nodules of Leguminosae. C. rapunculoides: Spongospora campanulae

3a On inflorescences, flowers or fruits => 27

3b On vegetative organs => 4

4a Malformations caused by ± early fruiting fungi at surface => 25

4b Malformations without externally developing fungal fruiting bodies => 5

5a Malformations caused by animal parasites => 6

5b Hardly 1 mm long, hemispherical, ± golden-yellow translucent wart-shaped galls, usually many on underside of rosette leaves, also on stalks as well as on basal stem parts; sometimes ± coalescing. C. herminii, patula, rotundifolia, scheuchzeri: Synchytrium aureum

6a Malformations terminally on main- and side shoots, on buds or on leaves, sometimes including stem parts => 7

6b Axial parts of stem, often the lower parts with ± expanded spindle-shaped swelling with single or several rimmed depressions containing froth-covered nymphs of causers. Campanula spp.: Planchonia arabidis

7a Malformations mainly on leaves, sometimes encroaching onto stems => 14

7b Malformations on shoot tips or on buds => 8

8a Galls loose, spindle-shaped, consisting of ± unfolded leaves, also tuft-like => 11

8b Galls closed, compact, ± onion-like, usually fleshy => 9

9a Rotund or egg-shaped galls, up to 5 mm long, on shoot tips or lateral buds; on larger organs sometimes ± joined into larger complexes => 10

9b Similar, often more slender gall, up to 8 mm long. Also flower primordia severely stunted and disfigured, sometimes overtopped by calyx lobes. Containing several red larvae. C. rapunculus: Dasineura rapunculi

10a Onion-like galls in axillary buds; often overtopped by short rudiments of leaf blades; on shoot tip often united into irregularly composed groups, up to 12 mm broad. Containing one or more brick-red larvae. C. cochleariifolia, persicifolia, rotundifolia, scheuchzeri, trachelium: Geocrypta campanulae

10b Similar, more egg-shaped gall. Contains single yellow-red larva. C. rotundifolia, scheuchzeri: Unidentified gall midge

11a Malformations tuft-like or elongate spindle-shaped => 12

11b Shoot tip stunted; leaves densely clustered, broadened at base and discoloured, terminally spreading; contains several white larvae in axils. C. trachelium: Unidentified gall midge

12a Tufts ± spindle-shaped => 13

12b Tuft terminally on shoot, up to 15 mm long, egg-shaped or globular, containing yellow larvae. C. glomerata: Dasineura campanularum

13a Tufts oblong spindle-shaped, with abnormal pubescence. Leaves rolled inwards and upwards or folded, thickened, abnormally pubescent. Containing a single orange larva. C. barbata, rapunculoides, thyrsoides: Unidentified gall midge

13b Similar gall, not additionally haired. Leaves rolled, slightly thickened and discoloured. Larva whitish, translucent. C. bononiensis, rapunculoides: Dasineura acuminata

14a Leaf blade rolled inwards, curled or swollen locally => 15

14b Leaves disfigured, almost felt-like pubescent. Stem shortened. C. cochlerariifolia, rotundifolia: cf. Aceria campanulae

15a Rolling or curls of leaf blade => 17

15b Leaf blade with ± expanded swelling => 16

16a Crater-shaped, greenish, wrinkled rimmed proliferation on upper side, close to midrib or a side vein; venation disfigured and thickened. C. bononiensis: Inducer unknown

16b Midrib and shortened stalk of several variously distorted rosette leaves swollen, spongy. Tissue brittle, pale green. Galls variously encroaching into the ± stunted leaf blade. C. barbata, carpatica, persicifolia: Ditylenchus dipsaci

17a Leaf blade with margin loosely rolled inwards and ± protruding, curls, caused by aphids or spittlebugs => 22

17b Narrow marginal roll, caused by gall mites or gall midges => 18

18a Margin rolled upwards, with cartilaginous or fleshy thickening, ± discoloured. Midge galls => 21

18b Narrow roll upwards, not discoloured. Mite galls => 19

19a On species with small leaves => 20

19b On C. latifolia, trachelium: Unidentified gall mite

20a Leaf roll tubular, narrow, sometimes remarkably thickened, not conspicuously felt-like pubescent. C. cochleariifolia, rotundifolia: Aceria campanulae

20b Similar roll with abnormal, ± felt-like pubescence. C. cochleariifolia, scheuchzeri, rotundifolia: Unidentified gall mite

21a Roll usually discoloured violet; especially on upper leaves of sterile shoots, also on leaves inserted on roots. Leaf blades sometimes bulging. Usually containing only a single red larva. C. cochleariifolia, latifolia, ? rotundifolia, scheuchzeri: Dasineura thomasi

21b Leaf blade often with cartilaginous, ± wrinkled, usually discoloured upwards roll on both sides. C. bononiensis, rapunculoides: Dasineura acuminata

22a Leaf blade rolled inwards, caused by aphids => 23

22b Leaves loosely deflected, roll- or spoon-like; curled and deep green close to infestation. Contains froth-covered nymph. Sometimes several similarly curved leaves are loosely converging, nest-like, on locally ± stunted and distorted stem. Campanula spp.: Philaenus spumarius

23a Leaves rolled downwards or bent and curled => 24

23b Leaves rolled upwards; stem with shortened, twisted internodes. C. rotundifolia: Unidentified aphid

24a Leaves rolled downwards. Aphid dark red-brown, with rows of black dots, making dark red spots if crushed. Mainly on C. rapunculoides, also on C. cervaria, glomerata, patula, sibirica, trachelium: Uroleucon rapunculoides

24b Leaves deflected, ± curled. Aphids black. C. rapunculoides, trachelium: Aphis fabae

25a Leaves thickened at infestation site, yellowish-green, with whitish-grey down of branched conidiophores on underside. Often the entire plant stunted; leaves in rosettes, non-flowering. C. rapunculoides: Peronospora sp.

25b Upper side of the leaves with pale, slightly embossed patches; on the corresponding underside is a greyish white fungal bloom, consisting of erect, distally strongly branched conidiophores. C. rapunculoides, rapunculus: Peronospora erinicola

25c Sori rust-brown, usually on leaf underside; causing facultatively minor swellings and distortions on venation, on petioles and young stem parts. Telia with 2-celled teliospores, provided with minute warts. Uredinia absent. Usually rare, biologically specialised, also morphologically distinct rusts of the species complex: Puccinia campanulae s. lat.

a On C. cochleariifolia: Puccinia rytzii

b On C. rapunculus: Puccinia campanulae

c On C. rotundifolia: Puccinia campanulae-rotundifoliae

d On C. scheuchzeri: Puccinia campanulae-scheuchzeri

e On C. uniflora: Puccinia novaezemblae; distinguished by glabrous spore walls

f Rust fungi reported from C. glomerata, rapunculoides, trachelium, etc., are assigned to above-mentioned species complex

26a On flowers and inflorescences => 28

26b Ovaries or fruit, including receptacle, succulent, swollen, sometimes distorted; pistil and stigmas thickened, greened; the remaining flower parts necrotic. Contains a single or several larvae. Campanula spp.: Miarus campanulae

27a Flowers or inflorescence greened or leafy => 31

27b Malformation of inflorescence primordia or of flower buds, flowers lacking conspicuous greening => 28

28a Flowers, flower buds unopened and thickened => 29

28b Primordia of inflorescences severely stunted, ± reddened. Flower primordia clustered; especially ovaries disfigured and overtopped by the distorted calyx lobes. Containing several red larvae. C. rapunculus: Dasineura rapunculi

29a Flower buds inflated => 30

29b Flower buds transformed into a succulent, onion-like gall. Contains a single or several brick-red larvae. C. cochleariifolia, persicifolia, rotundifolia, scheuchzeri, trachelium: cf. Geocrypta campanulae

30a The unopened flowers are strongly enlarged at base. Calyx ± stunted; stamens thickened. Larvae white, jumping. C. barbata, cochleariifolia, rapunculoides, rhomboidalis, rotundifolia, scheuchzeri, trachelium: Contarinia campanulae

30b Similar malformations on C. cochleariifolia, rotundifolia, scheuchzeri containing white, non-jumping larvae: Dasineura campanulae

= The curculionid Miarus graminis causes galled flowers of C. glomerata, rotundifolia, trachelium.

31a Flowers greened. C. rotundifolia: Aceria chloranthes

31b Many flowers completely greened over large parts; stunted inflorescence excessively branched and, especially on side branches, the small leaves densely clustered, rolled and curled, often with proliferations on upper side. Host often pubescent with excessive development of hairs. Campanula spp.: Aculus schmardae

gallers on Senecio

pub 10.xii.2019

Dichotomous table for gallers on Senecio

by Hans Roskam

1a On above-ground parts => 3

1b On roots => 2

2a Roots close to the surface with an expanded weak swelling, centrally with a wide canal, protruding into the stem and containing a caterpillar. Jacobaea erucifolia, J. vulgaris: Epiblema scutulana

2b Root with small, nodule- or spindle-shaped, cylindrical galls, up to 6 mm long S. vulgaris: Meloidogyne hapla

3a On capitula => 23

3b On vegetative organs => 4

4a Extensive malformations of plant parts; or galls on shoot tips, buds or leaves => 8

4b Galls on stems => 5

4c Stem and leaves greatly swollen and distorted by vivid orange aecia; long, dark brown to black telia may rarely be found at the same time; frequent. Jacobaea vulgaris, Pallenis maritima, Pericallis hybrida, Senecio spp.: Puccinia lagenophorae

4d Stem and leaves slightly swollen and distorted; with powdery orange uredinia and waxy reddish telia; rarely recorded. Senecio s.lat.: Coleosporium senecionis

5a Swelling elongate, situated at different positions. A caterpillar with distinct head capsule lives in a canal in the pith, extending beyond the swelling. Stem close to the gall considerably stunted or completely degenerating, overgrown later on by lower lateral shoots => 7

5b Galls plump, inhabited by larvae lacking a distinct head capsule => 6

6a Stem with padding, often developed on one side, distinctly curved swelling. Galls predominantly in upper stem part, sometimes with several, ± amalgamating. Several yellowish-white jumping larvae. Jacobaea aquatica, erratica, erucifolia, paludosa, vulgaris; Senecio leucanthemifolius subsp. vernalis, sylvaticus, viscosus, vulgaris: Contarinia jacobaeae

= White, non-jumpin, larvae of the gall midge Jaapiella crinita develop as inquilines in galls of Contarinia jacobaeae

6b Stem swollen immediately under the inflorescence. One yellow larva. Jacobaea vulgaris, Senecio sylvaticus: Unidentified dipteran

6c Several rotund galls, up to 10 mm long variously shaped and situated terminally on main- and lateral shoots; also in the inflorescences as well as in buds, petioles and capitula; often extending into neighbouring organs. Centrally one or several large larval chambers with pale yellow to flesh-coloured larvae. Jacobaea vulgaris; Senecio nemorensis, ovatus incl. subsp. stabianus, sarracenicus, sylvaticus: Contarinia aequalis

7a Stem over the galled part ± irregularly thickened, with spindle- to almost nodule-shaped bulges. Galls up to 30 mm long, predominantly on apical sites, with an ejection hole for frass, sometimes bursting. Leaves degenerating. One ivory- to dirty olive-green, black-headed caterpillar. Jacobaea aquatica; Senecio nemorensis, ovatus incl. subsp. stabianus, sarracenicus, sylvaticus: Platyptilia nemoralis

7b Stem in upper third, sometimes immediately below the inflorescence, over a length of 25–35 mm, spindle-shaped to cylindrically swollen. One reddish-yellow caterpillar, the underside paler, with pale brown head capsule. Jacobaea erucifolia, vulgaris; ? Senecio sylvaticus.: Cochylis atricapitana

7c Similar stem gall, in Jacobaea aquatica, vulgaris; Senecio nemorensis, sarracenicus: Platyptilia isodactylus

8a Wart- bulge- or cup-shaped galls on leaves, induced by fungi or psyllids => 16

8b Malformations of large plant parts or galls on shoot tips or lateral buds => 9

9a Malformations on buds or on shoot tips => 15

9b Extensive malformation of the complete plant or malformation of several leaves on the shoot tips => 10

10a Malformations by aphids or cercopids => 11

10b Early infected stems markedly stunted; basally over large extension spongy, swollen, pale green, with rugose, partially undulating surface. Later infestation results in locally expanded one- or often all-sided stem swellings, in conjunction with twisting and curving. Involved organs severely stunted; sometimes also irregularly thickened at the base. Senecio vulgaris, viscosus: Ditylenchus dipsaci

11a Malformations of various kind, usually not specific for the inducer; aphids => 12

11b Large areas on the intensively green site of infestation, strongly bent at leaf apex and ± deflected at margin, curled. Infestation of young stem parts results in stunting and bending of the internodes with ± clustering of disfigured leaves. Senecio s.lat.: Philaenus spumarius

12a Aphids dark green to black => 14

12b Aphids brighter => 13

13a Leaves ± stunted, margins loosely deflected or rolled, curled. Often many per plant, resulting sometimes in conspicuous malformations. Aphid 1.1–2 mm long, bright- to yellow-green. Senecio s.lat.: Brachycaudus helichrysi

13b Leaf blades curled, margins deflected; similar malformations on often many, ± clustered leaves on tips of shoots. Aphid 2–2⅓ mm, greenish to yellowish with large glossy black dorsal patch. Jacobaea aquatica, vulgaris; Senecio spp: Brachycaudus cardui

14a Leaves clustered at tips of shoots and young inflorescence compact, strongly malformed. Leaf blades bent, loosely rolled or curled; capitula ± stunted and disfigured. Aphid 1.5–2 mm long, dirty green to black. Antennae a little longer than half the body length; tibiae black. Jacobaea aquatica, vulgaris; Senecio gallicus, ovatus subsp. stabianus, vulgaris: Aphis jacobaeae

14b Terminal leaves clustered on stunted shoots, deformed, loosely curved downwards and curled. Young plants sometimes completely disfigured. Aphid about 2.5 mm long, dark grey-green to dull black. Antennae half the body length. Legs yellowish annulated. Jacobaea maritima, vulgaris; Senecio spp.: Aphis fabae

15a Shoot tips or lateral buds stunted; Leaves markedly stunted in their development. ± wrinkled and discoloured, heavily whitish pubescent, clustered into an elongated, bud-like shoot. Jacobaea aquatica, vulgaris; Senecio sylvaticus, vulgaris: Aceria leioprocta

15b Terminal- or lateral buds transformed into an irregular, rotund-barrel-shaped, succulent gall. A large chamber inside containing pale-yellow to flesh-coloured larvae. Jacobaea vulgaris; Senecio nemorensis, ovatus incl. subsp. stabianus, sarracenicus, sylvaticus: Contarinia aequalis

16a Wart- or bulge-shaped fungus galls => 17

16b Leaf blade curled, with weak embossment protruding on the upper side. S. nemorensis, ovatus: Trioza senecionis

17a Galls conspicuous; occupied at an early stage by a dusting of sori => 18

17b Galls wart-shaped, coalesced, almost 1 mm long; golden yellow; often many on the underside of basal leaves or on the base of young stems. Senecio vulgaris: Synchytrium aureum

18a Sori ± clearly thickened, bearing aecia => 20

18b Leaf blade often with rotund, bulging pads on the underside or leaf veins, petioles and axial parts with ± spindle-shaped, telia bearing elevations => 19

19a Dark brown, small sori, often occurring on the underside of the leaves, sometimes clustering into larger groups, in that case clearly cecidogenic. Jacobaea alpina, aquatica, subalpina, vulgaris; Senecio spp.: Puccinia expansa

19b Rotund, only slightly- or not thickened, ± yellowish margined sori, 5–10 mm wide, on leaf underside. Senecio ovatus, sarracenicus: Puccinia uralensis

20a Host-alternating fungi, which develop yellowish swellings on Senecio species, bearing their aecia and partially pycnidia => 21

20b Fungus host-specific; on the host only sori with telia develop, besides aecia. Swellings often insignificant. Aecia with whitish peridium; in irregular, loose, smaller groups, rarely extended, on the leaf underside. Jacobaea alpina, aquatica, subalpina, vulgaris; Senecio spp.: Puccinia expansa

21a Aecia on Tephroseris spp. => 22

21b Various rust fungi; recorded from:

a Senecio viscosus, vulgaris: Puccinia opizii

b Jacobaea vulgaris; Senecio viscosus, vulgaris: Puccinia schoeleriana

c Senecio nemorensis, ovatus: Puccinia silvatica

d Jacobaea alpina, aquatica, erucifolia, paludosa, vulgaris; Senecio ovatus, sylvaticus, viscosus, vulgaris: Puccinia senecionis-acutiformis

22a Aecia on the leaf undersides in rotund, often yellow-brown, violet-margined spots. Tephroseris longifolia subspp. brachychaeta, gaudini: Puccinia baldensis

22b Aecia usually on the leaf underside in rotund yellow spots. Tephroseris helenitis, palustris: Puccinia eriophori

= Aecidium senecionis-crispati has been described from Tephroseris crispa.

23a Swollen capitula on otherwise normally developed plants => 24

23b Clustered, shortened, leafy and greened capitula on ± atrophied plants. Jacobaea aquatica, J. erucifolia, J. vulgaris, Senecio sylvaticus, vulgaris: Unidentified ? gall mite

= Stunted but not greened flowers of Jacobaea vulgaris are caused by an unidentified thrips

24a Larvae inside the galls => 25

24b Larvae between the achenes. Capitula not opening, markedly swollen, rotund to broad ovoid, the base especially succulent thickened and yellowish to ± reddened there. Several yellowish-white, jumping larvae. Mainly on Jacobaea vulgaris; less frequent on Jacobaea aquatica, erratica, erucifolia, paludosa, vulgaris; Senecio leucanthemifolius subsp. vernalis, sylvaticus, viscosus, vulgaris.: Contarinia jacobaeae

24c Thickened capitula of S. ovatus containing yellowish, non-jumping larvae of Dasineura senecionis

24d Flower head only inconspicuously swollen bearing a cone of froth which covers a fly maggot. Jacobaea aquatica, incana subsp. carniolica, vulgaris; Senecio ovatus; Tephroseris crispa: Botanophila seneciella

25a Capitula usually only slightly swollen. Larvae in the thickened receptacle => 26

25b Major part of the flower head deformed to form a succulent gall. All organs more or less incorporated in the gall formation, which may extend to the stalk. Inside a large cavity containing pale yellow to succulent-red larvae. Jacobaea vulgaris; Senecio nemorensis, ovatus incl. subsp. stabianus, sarracenicus, sylvaticus: Contarinia aequalis

26a Larvae lacking distinct head capsule and legs => 27

26b Larvae with head capsule and thoracic legs in the slightly enlarged receptacle. S. viscosus: Unidentified lepidopteran

27a Capitula at base often heavily swollen on all sides and discoloured yellow-green, not opening, usually large cone-shaped. Fruits usually withered. Containing a single larva. Senecio s.lat.: Sphenella marginata

27b Receptacle externally only weakly swollen, often on one side, and hardened; later bulging upwards locally. Capitula not opening, mostly cylindrical to narrow cone-shaped. Containing a single larva. Senecio s.lat.: Trupanea stellata

gallers on Crataegus

pub 9.xii.2019

Dichotomous table for gallers on Crataegus

by Hans Roskam

1a On flowers => 23

1b On vegetative plant parts => 2

2a On buds, leaves and thinner twigs => 4

2b In root, trunk or on thicker branches => 3

3a Irregular lumpy swelling on root, 10 mm across or much larger; soft at first, later woody; contains red, purple or brown woolly aphids covered with copious white wax; gall persists long after aphids have left; rare. Crataegus spp.: Eriosoma lanigerum

3b Branches or stems often with conspicuous, club- or barrel-shaped swellings. Crataegus spp.: Viscum album

4a Malformations of various shape, soon occupied by fructifications of fungi => 20

4b Malformations caused by animals => 5

5a Aphid galls => 15

5b Other causers => 6

6a On younger stems, shoot tips or leaves => 7

6b Buds slightly swollen, not opening, occasionally abnormally pubescent. C. laevigata, monogyna: Eriophyes calycobius

6c Vegetative bud unopened, transformed into a rotund mass of small, strongly folded leaves, about 5 mm wide, the external ones making a sort of hood enveloping a shell of aggregated dying leaves. Crataegus spp.: Anthonomus bituberculatus

7a Malformations on single, or several terminal leaves, loosely arranged => 9

7b Galls on thin stems or on shoot tips => 8

8a Leaves on distinctly stunted, slightly thickened shoot tip often in many densely tuft-like clusters. Leaf blades sessile, ± stunted, rugose, occupied by many bolt-shaped or globular green or reddish proliferations. Between the inner, very small leaves are many white, later orange larvae. C. azarolus, coccinea, laevigata, monogyna, rhipidophylla: Dasineura crataegi

= Associated are the yellowish larvae of the inquiline gall midge Prolauthia circumdata.

8b Shoot axis with brown-green swelling, sometimes extending onto the petiole, with easily loosening epidermis. C. laevigata, monogyna: Unidentified gall midge

= The “Hawthorn twig gall midge” Resseliella crataegi, with larvae living gregariously under bark, has not been observed to cause galls.

8c Bark of younger twigs usually with several, ± distinctly rimmed depressions, which contain a rotund, whitish- to brownish-grey scale insect, the inducer. C. rhipidophylla: Epidiaspis leperii

9a Leaves curled or with many small swellings or pocks => 12

9b Leaf margin rolled or leaf blade abnormally pubescent => 10

10a Rolls of leaf margins => 11

10b Underside of leaf with white or violet-red erinea of slightly club-shaped hairs. C. coccinoides, laevigata, macrocarpa, monogyna, nigra, rhipidophylla, sanguinea: Phyllocoptes goniothorax

10c Upper side of leaf slightly protruding at junction of midrib and side vein; corresponding area on underside weakly pubescent. Crataegus spp.: Eriophyes albaespinae

10d Underside of leaf with a longitudinal groove, abnormal pubescence absent. C. laevigata, rhipidophylla: Aculops crataegumplicans

11a Leaf margin tightly rolled downwards, with short club-shaped, at first white, then brownish hairs sometimes extending as erinea into the leaf blade or developing there as isolated patches. C. coccinoides, laevigata, macrocarpa, monogyna, nigra, rhipidophylla, sanguinea: Phyllocoptes goniothorax

11b Leaf roll, containing several red larvae. C. monogyna, laevigata: Unidentified gall midge

12a Leaf blade with many pocks or small swellings => 13

12b Several leaves of suckers on curved stems bent together into a loose aggregation. Leaf blades ± crumpled. Containing a froth-covered nymph. Crataegus spp.: Philaenus spumarius

13a Leaf blade with one-sided archings => 14

13b Leaf blade with many pocks protruding on both sides, often pale green; with narrow opening on underside, occasionally also on upperside. C. laevigata, monogyna: Eriophyes crataegi

14a Leaf blade with many small bulging swellings, yellowish or often carmine-red. Froth-covered nymphs in grooves on underside. C. laevigata, monogyna, rhipidophylla: Cacopsylla melanoneura

14b Leaf blade browned by vagrant gall mites. C. macrocarpa, monogyna, rhipidophylla: Calepitrimerus armatus

14c In similar malformations on hawthorns during the same period also lives Cacopsylla peregrina

14d Leaf blade with small depressions on the underside, and corresponding tiny bulges, often coloured red, on the upper side. In each cavity is one flat froth-covered nymph. C. laevigata, monogyna: Cacopsylla affinis

= The psyllid Cacopsylla crataegi is only weakly cecidogenic, and often reported only as inquiline, or successorium (secondary inhabitant) in aphid galls.

14e Leaf blades usually bent downwards along the venation. Malformations without abnormal pubescence. C. laevigata, rhipidophylla: Aculops crataegumplicans

15a Leaves variously curled, leaf blades not discoloured or sometimes marbled yellow. Malformation usually with many leaves, loosely arranged on shoots or ± clustered on shoot tips => 17

15b Leaves swollen, bladder-like, and conspicuously discoloured yellowish or reddish. Galls caused by several Dysaphis species, all host alternating and difficult to separate => 16

16a Leaf blade usually keel-shaped, curved downwards; segments between the veins especially close to the midrib strongly inflated, bladder-like, discoloured yellowish, not red. Galls mainly on several leaves distributed over the plants. C. laevigata, monogyna: Dysaphis ranunculi

16b Galls usually strongly reddened, otherwise not different from previous species. Often on several neighbouring leaves occurring already during unfolding of leaves. Larvae usually greenish or pink. Aphids mainly distinguished by their different host alternation. Aphids interbreed on Crataegus. Exules on roots, at stem base or sheaths, rarely on leaf blades of basal leaves of various Apiaceae:

a Migrating to Daucus carota, sativus (Anthriscus, Aegopodium): Dysaphis crataegi

b Migrating to Aethusa cynapium: Dysaphis crataegi subsp. aethusae

c Migrating to Angelica: Dysaphis angelicae

d Migrating to Apium graveolens and Petroselinum crispum: Dysaphis apiifolia subsp. petroselini

e Migrating to Heracleum, Conium: Dysaphis lauberti

f Migrating to Laserpitium, Anthriscus: Dysaphis laserpitii

g Migrating to Petroselinum, (Levisticum officinale, Conium): Dysaphis apiifolia subsp. petroselini

h Migrating to Pastinaca sativa: Dysaphis crataegi subsp. kunzei

17a Leaves not conspicuously discoloured => 18

17b Several leaves at shoot tip loosely arched, marbled yellow, soon drying. C. laevigata, monogyna, rhipidophylla, sanguinea: Prociphilus pini

17c Cherry-red to crimson curled-leaf galls in spring. Crataegus laevigata, monogyna: Dysaphis apiifolia

17d Red curled-leaf galls on leaves. C. curvisepala: Dysaphis incognita

17e Pale green or red curled-leaf galls. C. orientalis: Dysaphis virgata

18a Aphids green => 19

18b Aphids black; rolling and curling of young leaves. Crataegus spp.: Aphis fabae

19a Leaves on the unshortened shoots normally distributed or sometimes loosely clustered at shoot tip. Midrib conspicuously bent, screw-like, leaf blade sometimes undulate, nested, loosely or more compactly bent downwards. Aphid with short, thick green siphunculi. C. coccinea, laevigata, monogyna: Rhopalosiphum oxyacanthae

19b Leaves at stunted ends of shoots bent downwards over tip and margins rolled. Aphid with rather long black siphunculi. Crataegus spp.: Aphis pomi

20a Leaves curled or swollen, bladder-like, also young stems partially ± thickened and curved, occupied by grey-white fungal fructifications => 22

20b Considerable yellowish, also reddened, pad- or bulge-shaped swellings on leaves, young stems and even fruits. Galls occupied by spermogonia and aecia => 21

21a Peridium cylindrical, 2–3 mm long, lacerated brush-like later on, divided from the tip into many long lobes. Lateral walls of peridium cells with many, irregularly shaped tubercles of different size. Crataegus spp.: Gymnosporangium clavariiforme

21b Aecia similar. Lateral walls of peridium cells with strong transversely and obliquely running tubercles and ridges. Crataegus spp.: Gymnosporangium confusum

22a Leaves with yellowish-green or reddened bladder-like swellings, at maturity appearing white-frosted because of presence of many asci. Sori occasionally slightly arched, usually on one side, and ± curved swellings on young shoots, flower peduncles and even floral parts; sporadically developing almost witches’ broom-like malformations. C. laevigata, monogyna, nigra, sanguinea: Taphrina crataegi

22b During development of infected young shoots, according to response ability, the internodes partially appearing shortened, slightly thickened, partially etiolated, elongated and in case of mainly one-sided infestation ± conspicuously curved and often ± reddened. Diseased organs covered with a loose white mycelium. Crataegus spp.: Podosphaera clandestina

23a Malformations caused by fungi on flower parts or young fruits => 21, 22

23b Malformations caused by animals => 24

24a Outer parts of flower buds, especially basally, slightly swollen, not opening. Between the inner parts occur larvae with inconspicuous head capsules => 25

24b Receptacle and ovaries sometimes facultatively slightly swollen. Flowers remain closed, corolla distinct between healthy flowers because of its premature browning. Inside is a single larva with distinct head capsule. C. laevigata, monogyna: Anthonomus pedicularius

25a Larvae ivory-coloured, jumping. C. laevigata, monogyna: Contarinia anthobia

25b Larvae red, non-jumping. C. crus-galli, laevigata, monogyna: Dasineura oxyacanthae

= Inquiline of Dasineura oxyacanthae, larvae orange-coloured, non-jumping: Dasineura fusca

gallers on Geranium

pub 8.xii.2019

Dichotomous table for gallers on Geranium

by Hans Roskam

1a Galls on root collar or on parts above ground => 2

1b Roots with swellings only a few mm long, nodular or spindle-shaped, which bear side roots. Geranium spp.: Meloidogyne hapla

2a Malformations on inflorescences or flowers => 25

2b Malformations on vegetative parts => 3

3a Malformations caused by fungi, developing on surface or fruiting there => 17

3b Malformations caused by animals => 4

4a Gall formation includes single groups of organs or their parts => 5

4b Complete plant disfigured; basal stem parts variously swollen, spongy, from there developing organs ± reduced and disfigured. G. dissectum, molle: Ditylenchus dipsaci

5a Malformations on plant parts above ground => 6

5b Adventitious buds on root collar transformed into cauliflower-like proliferations, up to 20 mm long. G. molle, pusillum: Cause unknown – ? gall mite

5c Repeatedly reported leafy proliferations, have been attributed to Rhodococcus fascians

5d Closed fleshy proliferations, tuberculate at surface. Geranium spp.: Agrobacterium tumefaciens

6a Malformation of several organs on shoot tips or only on leaves => 7

6b Axial parts of shoot, also petioles, with bulging swellings with rimmed depressions containing the causer. Geranium spp.: Planchonia arabidis

7a Leaves with narrow rolls of margin or with strong pubescence => 10

7b Leaves lacking conspicuous pubescence; leaf blades deflected or loosely rolled, ± curled => 8

8a Malformations induced by aphids or spittlebugs => 9

8b Leaf blade ± curled, without particular curving. G. palustre, pratense: Unidentified hemipteran

9a Leaf blade strongly deflected, often ± nest-like, variously curled, dark green close to infestation. Geranium spp.: Philaenus spumarius

9b Several terminal leaf blades of shoots ± wrinkled and disfigured; tips loosely deflected or rolled. Shoot axis shortened if strongly infected, as well as stalks of clustered leaves. Geranium spp.: Acyrthosiphon malvae

10a Malformations distinguished by strong pubescence => 13

10b Narrow roll of leaf margin lacking conspicuous pubescence => 11

11a Malformation of many terminal leaves on shoots => 12

11b Leaflets often in single basal leaves, rarely in stem leaves, sack-shaped, rolled upwards, lighter. Veins thickened, containing several white larvae. G. sylvaticum: Unidentified gall midge

12a Leaf blade more subdivided, partially narrowly rolled inwards at margin. G. robertianum: Unidentified gall mite

12b Leaves on shortened shoot tip accumulated, tuft-like, tips rolled upwards, appearing almost needle-like, ± thickened, often reddened. Geranium spp.: Aceria geranii

13a Leaf blades with conspicuous rolls of margin => 14

13b Leaf blades with mainly yellow- or red discoloured irregular hunchbacked archings, covered with a white-silk-like glossy, abnormal pubescence. Hairs cylindrical, frizzy. Erinea may also encroach onto petioles, shoot axis and even calyx leaves. Geranium spp.: Aceria geranii

= The gall mite Aceria dissecti has been described from G. dissectum causing deformations of petals and young leaves, and shrivelling of leaves

13c Leaf margins hardly rolled inwards, more densely haired on both sides soon ± brownish discoloured. Mites free-living on leaf underside. G. caeruleatum, robertianum, sanguineum, sylvaticum: Epitrimerus geranii

14a Malformation of many clustered terminal leaves => 15

14b Malformations on shoot tips, of which axial parts, as well as petioles, are elongated and thinner. Leaflets rolled inwards and upwards, white erineum on underside. Inflorescences transformed into whitish capitula. Complete plant ± discoloured. G. molle: Unidentified gall mite

15a Leaves additionally subdivided due to infestation => 16

15b Shoot axis shortened, leaves accumulated, tuft-like, their tips rolled inwards and upwards, ± thickened, reddened, on many hosts conspicuously strongly pubescent. Geranium spp.: Aceria geranii

16a Shoot tip stunted, leaves ± finely subdivided, their tips ± rolled inwards, curved, twisted. Flowers ± distorted, accumulated into capitula, abnormally pubescent. G. pyrenaicum: Aceria schlechtendali

16b Similar malformations on G. dissectum, lucidum, molle, palustre, phaeum, sanguineum, sylvaticum: Aceria dolichosoma

17a Malformations bearing aecia and telia of rust fungi => 19

17b Malformations caused by mildew fungi => 18

18a Minor swelling, up to 1.5 mm long, situated mainly below the leaf blade on petiole, covered by at first white, then ± brown mycelium containing many punctiform perithecia. Geranium spp.: Podosphaera fugax

18b Grey-white down of conidiophores on leaf underside. Leaves usually completely diseased; at first developing faster, longer stalked than healthy ones; leaf blades smaller, yellowish-green, the margins usually loosely rolled downwards. Geranium spp.: Peronospora conglomerata

= The mildew Plasmopara wilsonii causes sharply delimited upper surface leaf spots on G. molle, phaeum, initially some mm large, ultimately often filling the entire leaf; pale yellowish at first, in the end violaceous brown

= Other Plasmopara species on G. palustre, pratense, sylvaticum and relatives occurring in similar down, are much more frequent, but are never cecidogenic

19a Malformations bearing spermogonia and aecia => 22

19b Swellings with only telia => 20

20a Teliospores 2-celled => 21

20b Teliospores 1-celled; on leaf underside in small, dark-brown dusty sori. G. phaeum, ? palustre: Uromyces carpathicus

21a Sori remaining covered by epidermis for a long period. Spores with compact stalks. Pads on leaf underside small, on yellowish to reddish discoloured spots, or sori on spindle-shaped variously distorted bulges on stems, petioles or main veins, up to 20 mm long, usually red to crimson margined. G. albiflorum, macrorrhizum, pratense, sylvaticum: Puccinia morthieri

21b Pads soon naked and powdery; spores easily falling, with warty surface. Sori in densely arranged groups on ± distinct, small or elongated, up to even 80 or more mm long, often variously distorted bulges. Geranium spp.: Puccinia geranii-silvatici

21c On similar malformations on G. macrorrhizum develops Puccinia flahaulti

22a Mature aecia often arched and wide open => 23

22b Mature aecia appearing depressed, with narrow ostiole, margin star-shaped, lacerate, soon falling. Sori on leaf underside on large, rotund, slightly swollen, tuberculate, reddened spots. G. sanguineum: Puccinia oerteliana

23a Aecia on conspicuously thickened pads. Fungi monoecious. Peridium cells only loosely connected. Often conspicuous swellings, often associated with strong distortion, yellowish, sometimes ± reddish margined, on main veins encroaching into the leaf blade, or bulges of variable length on petioles and stems. Geranium spp.: Uromyces geranii

23b Aecia on not thickened leaf sites, surrounded by distinctly discoloured areas. Minor swellings may develop facultatively if sori encroach onto main venation. Fungi host alternating => 24

24a Sori mainly on intensively blood-red or crimson discoloured spots, sometimes additionally surrounded by a yellowish-green area. Peridium cup-shaped with rigidly connected wall cells; after opening the margin finely frayed and bent inwards. Geranium spp.: Puccinia polygoni-amphibii

24b Similarly without intensive marginal discolouration spots develop on G. columbinum, dissectum, molle, pusillum, rotundifolium: Puccinia polygoni

25a On flowers or fruits => 27

25b Expanded parts of inflorescence disfigured => 26

26a Malformation by aphids; the distorted and abnormal pubescent flowers are clustered. Geranium spp.: Acyrthosiphon malvae

26b Flower head-like clustering of disfigured, ± abnormally pubescent flower buds or calyx leaves, caused by gall mites => 14

27a Flowers ± swollen, unopened. Geranium spp. Several unidentified gall midges

27b Fruit basally ± strongly swollen. Containing several orange-yellow midge larvae. G. sanguineum, sylvaticum: Dasineura geranii

gallers on Silene

pub 7.xii.2019

Dichotomous table for gallers on Silene

by Hans Roskam

1a On parts above ground => 3

1b On subterranean parts => 2

2a Roots with 2–5 mm long, cylindrical galls, sporadically bearing side roots. S. atropurpurea, coeli-rosa, gallica, vulgaris: Meloidogyne hapla

2b Subterranean buds swollen, up to 4 mm across. Leaves clustered, tuft-like, succulent, whitish. Containing a single white larva. S. cucubalus, nutans, vulgaris: Dasineura subterranea

3a On inflorescences or flowers => 30

3b On stems, shoot tips, axillary buds or leaves => 4

4a Malformations on leaves, shoot tips, axillary buds or upper stem parts => 8

4b Basal rosettes or basal shoot organs largely disfigured, or leaf blades of rosette leaves with small yellowish warts => 5

5a Malformations caused by animals => 6

5b Leaf blades of rosette leaves with many warts, less than 1 mm long, multicellular, yellowish, occasionally coalescing; also on basal stem parts. Silene flos-cuculi: Synchytrium aureum

6a Malformations of basal leaves or leaf blades => 7

6b Young plants severely stunted. Stems stunted, spongy, swollen, inserted leaves variously disfigured. Silene spp.: Ditylenchus dipsaci

7a Basal leaves stunted. Leaves with their base spindle-shaped, converging; containing a green caterpillar, distinguished by its dark red first segment. It feeds on bast and cortex of young stems, which appear slightly thickened because of callus formation. S. nutans: Caryocolum sp.

7b Leaf blades of basal leaves in longitudinal direction knee-like bent, almost at right-angles, at any point. Breaking point close to midrib succulent, swollen, usually yellow-green, sometimes reddish. S. viscaria: Planchonia arabidis

8a On shoot tips, side shoots, and -buds or on leaves => 14

8b On axial parts of shoot => 9

9a Malformation caused by larvae with a distinct head capsule => 10

9b Swellings spongy; very variable in shape and expansion; with undulate or wrinkled surface. Silene spp.: Ditylenchus dipsaci

10a Malformations caused by a pith-tunneling caterpillar => 11

10b Stem with conspicuous ± spindle-shaped or cylindrical, tough-walled, glabrous swellings; caused by beetle larvae. Galls about 10 mm long and 5 mm thick, spindle-shaped or cylindrical; single or with a few together. Containing a single larva. Silene spp.: Sibinia femoralis

11a Galls very conspicuous on all sides, more than 15 mm long => 12

11b Stem stunted, ± swollen and curved. S. nutans, otites, viscaria: Caryocolum amaurella

12a Up to 30 (40) mm long and 8 (10) mm thick spindle-shaped-cylindrical gall, situated in the shortened internodes. A long tunnel in pith containing a dirty-grey, brown-headed caterpillar => 13

12b Swellings in axial parts of shoot tips. S. hayekiana, saxifraga: Caryocolum saginella

13a On S. dichotoma, gallica, italica, nutans,otitis, parviflora: Caryocolum cauligenella

13b On S. vulgaris: Caryocolum inflativorella

14a Galls on tips or buds of main- or side shoots => 25

14b Malformations mainly on leaves, sometimes encroaching into stem parts => 15

15a Malformations only minor, bearing sori of fungi => 22

15b Malformations caused by animals => 16

16a The causers are external on the galled tissue => 17

16b Spongy, swollen on both sides, ± wrinkled or undulate swelling on petiole or leaf blade; on narrow leaves also proliferating beyond the margin. Sometimes all parts of a rosette or of young plants are disfigured. Containing many eelworms. Silene spp.: Ditylenchus dipsaci

17a Leaves folded upwards over the midrib, ± discoloured. Malformations often on many plant parts. Caused by aphids => 18

17b Shoot axis locally stunted and ± curved. Leaves deflected over their tip, undulately curled; often clustered, nest-like, on the ± stunted stem parts. S. armeria, flos-cuculi, gallica, vulgaris: Philaenus spumarius

= As causer of similar malformations of shoot and leaves Taeniothrips atratus has been sporadically indicated.

18a Aphids pale green or yellowish => 21

18a Aphids red to dark-brown or black => 19

19a Aphids black => 20

19b Aphids red to dark brown. Leaves rolled downwards. S. alba, flos-cuculi: Myzus certus

20a Young leaf blades curled or rolled slightly downwards, caused by glossy black aphid with very short, rounded cauda. Silene spp.: Brachycaudus lychnidis

20b Flat, not discoloured bulges. S. alba, dioica. Wingless aphids with dull black body and tongue-shaped cauda: Aphis fabae

21a Apterae are whitish yellow to pale green, strongly wax-powdered; body length 1.4‒2.2 mm. Antennae half the body length. Siphunculi much shorter than the oblong, black cauda. S. vulgaris and varieties: cf. Brachycolus cucubali

21b Aphid yellowish or pale green, glossy, body length 1.4‒1.8 mm. Antennae about two-thirds of body length. Siphunculi weakly clavate, pale yellowish, only slightly longer than the yellow cauda. S. alpina, atropurpurea, flos-cuculi, nutans, otites, pendula, suecica, viscaria: Volutaphis centaureae

22a Malformations bearing yellowish to yellowish-white sori => 23

22b Minor rotund or oblong dense sori, sometimes bulging on venation, bearing dark-brown, 2-celled teliospores. Silene spp.: Puccinia arenariae

23a Aecia on several Silene species, S. nutans excepted => 24

23b Aecia mainly on S. nutans. Peridium short cylindrical, with white, deflected margin, subdivided into long narrow lobes. Uromyces inaequialtus

24a Malformations and aecia similar to those of preceding fungus. Spots on upperside often reddened. Aecia disc-shaped with strongly lacerate, deflected margin. Fungus lacking uredinia, with repeated development of aecia. S. cucubalis, alpina, densiflora, dichotoma, dioica, elisabethae, maritima, noctiflora, nutans, otites, rupestris, uniflora incl. subsp. thorei, vulgaris incl. subsp. prostrata: Uromyces behenis

= Witches’ broom-like malformations after infestation on S. uniflora may also be caused by this rust fungus.

= On S. otites the aecia of a host-alternating fungus (Aecidium otitis) have been recorded repeatedly with unknown life-cycle

24b Occasionally on cultivated plants of S. coeli-rosa, etiolated shoots with narrowed, paler leaves have been observed bearing on the undersides expanded, scattered yellow sori of Melampsorella caryophyllacearum

24c Aecia arranged in circular groups on hypertrophied sori on various organs, often crowded, more rarely extending over complete leaf; accompanied by spermogonia and often uredinia, less by 2-celled teliospores. Peridium very small, short cylindrical, with lacerate white margin. S. vulgaris, more rarely S. armeria, nutans, pendula, etc.: Puccinia behenis

25a Galls not excessively pubescent => 27

25b Malformations with abnormal whitish pubescence => 26

26a Leaves on shoot densely clustered. Leaf blades rolled and ± curved, almost linear; strongly white pubescent. In case of severe infestation the whole plant is atrophied. S. nutans: Unidentified gall mite

26b Almost bud-like accumulation of severely stunted, disfigured and abnormally haired leaves on shoot tips or in axillary buds. Containing several white larvae. S. alba, densiflora, dichotoma, dioica, latifolia,noctiflora, nutans, otites: Neomikiella lychnidis

26c Similar malformations of shoot tip, lateral buds, inserted unfolding leaves with loose, fleshy thickened marginal upward roll, exceptionally also downwards. Containing several white larvae. S. nutans: Unidentified gall midge

27a Malformations ± bud-like; caused by midge larvae => 29

27b Galls elongated, not of compact bud-like appearance, caused by midge larvae as well as other inducers => 28

28a Apical parts of plant distorted and discoloured. Silene alpina: Volutaphis alpinae

28b Leaves accumulated at the shoot tip over its length loosely upwardly rolled and ± thickened, bearing aphids or thrips. S. vulgaris, nutans: cf. Brachycolus cucubali

28c Several leaves of stunted shoots distorted, variously rolled and curved. S. latifolia, vulgaris: Taeniothrips atratus

28d The upper leaf pair of shoot tip erect, slightly thickened at base; the margins folded together or rolled. Containing several white to pale orange larvae. S. vulgaris: Macrolabis sp.

28e Similar galls containing white, jumping larvae. S. vulgaris: Contarinia cucubali

28f Leaves of shoot tip bushy clustered. S. nutans, vulgaris: Unidentified gall midge

29a Up to 10 mm long, ± onion-like, glabrous galls on the axillary buds or tips of lateral shoots. Containing several white larvae. S. vulgaris: Macrolabis sp.

29b Leaves bud-like accumulated on vegetative shoots, stunted, at base broadened, thickened and ± discoloured. Larvae pink-red. S. acaulis: Jaapiella alpina

29c The youngest one- or two pairs of leaves at the tip offside shoots are narrowly rolled into one another, swollen at base and discoloured. Containing several red larvae. S. viscaria: Jaapiella viscariae

29d Several rolled glabrous leaves form a spindle-shaped bud gall at the vegetative tip, contain many cream-coloured gall midge larvae. S. behen: Macrolabis behen

30a Malformation of flowers and of flower parts caused by fungi => 40

30b Malformations of inflorescences or single flowers caused by animals => 31

30c Fruits swollen. S. alba, dioica, fruticosa: Sibinia pellucens

31a Flowers unopened, swollen. Containing midge larvae => 34

31b Flowers ± stunted, their parts variously greened or leafy => 32

32a Malformations associated with a strong stunting of inflorescence => 33

32b Malformations usually restricted only to the sometimes shortened axial parts of stem. All flower parts leafy inside the hardly changed calyx. Inflorescence axis sometimes ± developing further. S. nutans, otites, rupestris: Aceria silenes

32c Malformations on S. “parviflora”: Eriophyes parviflorae

32d Flowers greened, transformed into small shoots bearing strongly pubescent little leaves. Also the vegetative buds may develop similarly disfigured, ± elongated, dense bunches. S. alba, dioica, latifolia vulgaris: Unidentified ? gall mite

32e Inflorescence stunted, disfigured, flowers clustered. Conspicuous pubescence absent, calyx widened, enclosing greened organs. Unidentified gall mite

33a Complete host stunted, flowers greened. S. dichotoma: Inducer unknown, ? virus

33b Flowers on usually severely stunted plants transformed into a widely protruding rosette of variously disfigured little leaves; stamens hardly disfigured but greened. S. alba: Inducer unknown – ? virus

33c Axial parts of inflorescence ± compact. Flowers ± clustered; calyx swollen. Organs inside variously disfigured and greened. S. vulgaris: cf. Brachycolus cucubali

33d Similar malformations on inflorescence. S. alba, vulgaris, occasionally S. baccifera, borysthenica, coronaria, dioica, italica, latifolia, uniflora, viscaria: Brachycaudus lychnidis

33e On S. dioica. Between strongly inflated calyx and stunted corolla: cf. Brachycaudus lychnidis or B. klugkisti

34a Galls usually with dense abnormal pubescence => 39

34b Galls not, or only slightly more pubescent than the normal organs => 35

35a On Silene species, but not S. alba, dioica, latifolia => 36

35b On S. alba, dioica, latifolia. Flower buds swollen, stunted, mostly unopened, on usually inconspicuously shortened axial parts of inflorescence. Containing several midge larvae, at first white, soon yellow, jumping: Contarinia steini

36a On Silene species, S. italica, vulgaris excepted => 37

36b On S. italica, vulgaris & subsp. glareosa: Calyx conspicuously swollen, largely unopened. Also the other flower parts enlarged and exceptionally ± leafy. Larvae yellowish to pale red: Jaapiella floriperda

36c Also described for similar galls on same hosts. Larvae white: Jaapiella cucubali or J. inflatae

37a On Silene species, but not S. atropurpurea, flos-cuculi, viscaria => 38

37b On S. flos-cuculi, viscaria, similar galls contain many red larvae: Dasineura praticola

37c On S. viscaria, similar galls contain only 4–8 red-yellow larvae: Jaapiella moraviae

38a On Silene species, but not S. nutans => 00

38b On S. nutans. Flowers stunted; ± globular, unopened, hardly swollen. Sometimes on the ± shortened axial parts clustered into rotund, sometimes weak whitish pubescent balls. Containing midge larvae. Unidentified gall midge

38c On S. nutans. Swollen flower buds, abnormally pubescent. Calyx strongly thickened. Larvae yellowish to pale red: Dasineura bergrothiana

39a On S. bupleuroides. Flower buds swollen, pale, unopened. Calyx thickened; corolla greened. Containing several yellow larvae. Unidentified gall midge

39b On S. otites. Flowers transformed into a rotund gall, up to 4 mm. Calyx abnormally pubescent. Corolla greened. Stamens ± normal. Containing red, non-jumping larvae. Dasineura sp.

39c Similar galls on S. parviflora, pseudotites: Unidentified gall midge

= In C-Eu occasionally galls on S. nutans, otites consisting of several, densely clustered, severely stunted and whitish pubescent buds; between the buds live white larvae of a gall midge assigned to Neomikiella lychnidis. Galls on these hosts often simultaneously occurring in vegetative shoot tips or lateral buds

40a Fungus fructifies in the ± distinctly swollen anthers. Spores separated, not arranged in easily decomposing balls; ± violet tinged. Other flower parts not galled => 43

40b Flower buds stunted, unopened, transformed into globular to broad egg-shaped galls. Inner part soon destroyed and displaced by a yellow- to tobacco-brown spore mass, consisting of many easily decomposing balls => 41

40c lowers leafy or partially greened. Organs variously disfigured, transformed into sometimes ± clustered, ± reddish tufts. S. viscaria: Cause unknown

41a On several Silene species, S. otites excepted => 42

41b On. Silene otites. Diseased flowers distorted; often distinctly swollen, for a long period unopened, corolla usually atrophied. Sori rupturing later on and with dusting: Microbotryum majus

42a On Silene alba, alpestris, dioica, nutans, rupestris, vulgaris. Flowers outwardly hardly changed. Infestation caused by this fungus results in an early opening of the flower accompanied by a shortening and swelling of the stamens, and in the female flowers a transformation into similarly disfigured anthers: Microbotryum violaceum

= Microbotryum heliospermae is an anther smut fungus occurring on alpine S. pusilla; M. silenes-saxifragae is an anther smut fungus on S. saxifraga

42b On many other Silene species. Flowers outwardly hardly changed. Spore mass usually pale grey-violet: Microbotryum silenes-inflatae

= The smut fungus Microbotryum silenes-dioicae transforms the content of the anthers of S. dioica into a brown vinaceous mass of spore

= Note: because the fungus leaves the ovary intact, the negative impact on the reproductive capacity of the flower is very limited. The real damage is caused by the gall midge Contarinia steini, see lead 35b.

= Microbotryum silenes-acaulis has been reported on S. acaulis, uniflora

43a On S. alba, dioica, latifolia, mollissima, nutans, repens, thymifolia, uniflora, velutina, vulgaris: Thecaphora melandrii

43b On S. flos-cuculi, viscaria: Thecaphora saponariae

gallers on Brassica

pub 6.xii.2019

Dichotomous table for gallers on Braasica

by Hans Roskam

1a On inflorescences, flowers or fruits => 23

1b On vegetative parts => 2

2a On parts above ground => 6

2b On root collar or on roots => 3

3a On roots => 4

3b Root collar with ± rotund, succulent swellings, about 8–10 mm long, containing a single larva. Galls, especially on perennial species, often many per plant and largely coalesced into ± lumpy gall complexes; sometimes also on the basal stem parts or close to surface on main root, especially on cabbage. B. napus, oleracea: Ceutorhynchus assimilis

= The snout beetles Aulacobaris coerulescens and Melanobaris laticollis have erroneously been reported as inducers of root collar-, root- and stem galls. The larvae develop by boring into ungalled roots or above ground stem parts and occasionally arrive in galls already produced by other inducers

4a Nodule-shaped swellings, only a few mm long, on the finer side roots, not noticeably swollen, transiently bearing cysts => 5

4b Main- or side roots often with very conspicuous, often clustered, spindle- or ± finger- to nodule-shaped, thick succulent, massive swellings; inside many cells with dense masses of minute spores. B. oleracea: Plasmodiophora brassicae

= Occasionally conspicuous nodular proliferations occur on main roots, or more frequently on above-ground parts, especially on forms of B. rapa. The tissue is, in contrast to that caused by Plasmodiophora brassicae, uniform coloured and without development of spores. Cause unknown, but some authors attributed these malformations to Agrobacterium tumefaciens

5a Roots with spindle-shaped or rotund, smaller, sometimes about pea- to exceptionally nut-size swellings caused by eelworms living inside. B. napus, oleracea, rapa, incl. subspecies and forms. Meloidogyne hapla

5b Inconspicuous, some side roots bearing root galls. B. napus, oleracea: Meloidogyne artiellia

5c Roots externally not swollen; inside with giant cells. Occasionally stronger development of side roots. Temporarily at surface with about poppy-seed sized, lemon-shaped, at first milk white, then browned cysts. Brassica spp.: Heterodera schachtii

5d On many cabbage species occur also the very similar, but slightly smaller, on average up to 0.6 mm, and more rotund cysts of Heterodera cruciferae

6a Malformations with white sori on surface => 22

6b Malformations caused by animal parasites => 7

7a Terminally on main- and side shoots => 18

7b On stems or leaves => 8

8a On stalks or leaf blades of leaves => 10

8b Stem with short spindle-shaped or elongate expanded swellings => 9

9a Thin stems with all-sided, thicker stems with one-sided, spindle-shaped swellings, 10–15 mm long, glabrous, also green inside. Contains a single larva. B. napus, nigra, oleracea, rapa: Ceutorhynchus chalybaeus

= Aulacobaris coerulescens, A. cuprirostris, A. lepidii, A. chlorizans have been reported as causers of stem galls. The larvae tunnel in the stem and the thicker roots; pupation in the gallery

9b Development of stem, especially of winter oil seed, stunted in spring, swollen over variable length, often ± s-shaped curved, often erupting over large expansion. In the strongly enlarged pith many, up to 7 mm long, yellowish-white apodous larvae with brownish, relatively large head capsule. B. napus, oleracea, rapa: Ceutorhynchus napi

= Occasionally has, especially for Brassica, been recorded Ceutorhynchus pallidactylus. Oviposition is not followed by gall formation. For B. rapa thickened leaf parenchyma has been reported caused by Ceutorhynchus leprieuri

10a Malformations mainly of leaf blades => 12

10b Galls on petioles or main venation => 11

11a Galls 10–15 mm long, compact, spindle-shaped, with glabrous surface, also green inside. B. napus, nigra, oleracea, rapa: Ceutorhynchus chalybaeus

11b Stems of germinating, also older plants or petioles, usually also the basal part of midrib shortened, spongy, swollen, yellowish green; at infestation sites brittle and necrotic, at surface ± undulately-wrinkled, variously on leaf blades, also encroaching on parts of rape. B. napus: Ditylenchus dipsaci

12a Leaf blade ± curled, loosely rolled inwards or folded => 14

12b Leaf blade with very narrow marginal roll or with lenticular galls => 13

13a Galls occurring from autumn to early spring; lenticular, up to 5 mm across, succulent, on both sides flat protruding, also green inside, especially conspicuous on yellowing parts, often many per leaf, often including main veins. Containing a single larva. B. rapa, rarely B. napus, oleracea: Ceutorhynchus leprieuri

13b Leaf blade with narrow marginal roll upwards. B. nigra: Inducer unknown

14a Malformations caused by aphids or spittlebugs => 15

14b Leaf blades to varied extent swollen and stunted, bent upwards along midrib; pale green; several whitish to pale yellow, jumping midge larvae on upper side between folds. B. napus, oleracea, rapa, souliei subsp. amplexicaulis: Contarinia nasturtii

15a Malformations caused by aphids => 16

15b Leaf blades of larger leaves deflected into mainly oblique rolls or distortions; usually curled and deep green close to froth covered froth-covered nymph. Brassica spp.: Philaenus spumarius

16a Aphid green => 17

16b Aphid black. Leaf blade at margin ± deflected, curled, infestation mainly on terminal stem leaves. Brassica spp.: ? Unidentified aphid

= Black aphids of Aphis fabae s.l. do not cause galls on Brassica. However, they may occur as inquilines in galls caused by other inducers

17a Leaf blade with expanded, conspicuously bulge- or bladder-like, pale green, on many species sometimes reddish or violet marbled folds or swellings; large colonies of densely grey-powdered aphids often on underside. B. napus, oleracea, rapa: Brevicoryne brassicae

17b Aphid not mealy powdered. Leaf blades of stem leaves often rolled downwards at margin, ± curled. B. napus, oleracea: Myzus persicae

18a Galls on tips of rosette leaves => 19

18b Tips of flowering main- and side shoots severely stunted; leaves as well as flower buds densely clustered, variously swollen at base. Similar malformations also on axillary, often hardly developed shoots. Between the galled parts are several whitish- to pale yellow, jumping larvae. B. napus, oleracea, rapa, souliei subsp. amplexicaulis: Contarinia nasturtii

19a Inducers live inside malformations => 20

19b Central leaves disfigured. Lower parts of petiole, vegetative point, especially at infected area, strongly swollen and bent sidewards. Between galled parts are several whitish- to pale yellow, jumping larvae. B. napus, oleracea, rapa, souliei subsp. amplexicaulis: Contarinia nasturtii

20a Shoot thickened over variable length, stunted. Leaves ± clustered, the inner ones often severely stunted or dead. Pith often contains several beetle larvae => 21

20b Stem of young plants completely or partially spongy, pale green; infestation similarly encroaching into petioles and leaf veins, mainly on underside. Galls contain many eelworms. B. napus: Ditylenchus dipsaci

21a Shoots, occasionally also leaf base of non-shooting forms, distinctly thickened; pith greatly increased. Vegetative point often largely stunted or necrotic. Several beetle larvae in heavily infected pith. B. napus, oleracea, rapa: Ceutorhynchus napi

21b Similar, usually weaker swellings inhabited by only 1 to 3 larvae. B. oleracea and forms. Ceutorrhynchus rapae

22a Loose down of branched conidiophores in ± expanded sori on the underside of only pale leaves. Rarely on leaf veins or young stems causing occasionally minor swellings, usually containing oospores. B. napus, nigra, oleracea, rapa: Hyaloperonospora brassicae

22b Sori on leaf underside rotund, on stem parts oblong-oval to spindle-shaped, compact, at first closed, glossy, porcelain-like, with mealy dusting after rupturing. Often many per plant; hardly cecidogenic on the leaf blades, on young stems often developing distinct pads. B. juncea, napus, nigra, oleracea, rapa: Albugo candida

22c Leaf with small hard, solid, gregarious pustules caused by fungus, less than 0.5 mm across. Brassica spp.: Synchytrium aureum

23a Malformations on single or many flowers or fruits; stem parts hardly disfigured => 26

23b Inflorescence disfigured => 24

24a Malformations caused by aphids or spittlebugs => 25

24b Racemes greatly shortened terminally; flower buds densely clustered, severely stunted, occasionally swollen at base. Between buds are several whitish- to pale yellow, jumping larvae. B. oleracea, rapa, souliei subsp. amplexicaulis: Contarinia nasturtii

25a Midrib locally swollen and severely stunted, usually bent to one side; flowers clustered, variously disfigured. Leaves distorted and curled. Containing a froth-covered nymph. Brassica spp.: Philaenus spumarius

25b Inflorescence broom-like disfigured and bent, longitudinal growth stunted. Flowers often mostly necrotic; occasionally also several largely disfigured shoots. Stems at first bearing ± densely grey powdered aphids. B. napus, oleracea, rapa: Brevicoryne brassicae

26a Malformations of ovaries or fruits => 29

26b Malformations of flowers => 27

27a Single or several buds of inflorescence swollen, unopened => 28

27b Usually consecutive flowers of large parts of inflorescence, often terminally of raceme variously disfigured; especially the ovaries prematurely elongated and increasing towards the top, swollen like enlarged, slender Capsella siliques; stamens and corolla disfigured, greened and often, like calyx necrotic. B. napus, oleracea and forms. Cause unknown – ? virus disease

28a Gall ± globular; calyx enlarged; corolla shortened; stamens disfigured, their filaments swollen and bent; anthers aborted; ovaries stunted, swollen; style and stigma necrotic. Containing several white, later on pale yellow, jumping larvae. B. oleracea, rapa, souliei subsp. amplexicaulis: Contarinia nasturtii

28b Similar flower galls with several, but non-jumping, larvae which are also white when mature. B. barrelieri, napus, oleracea, rapa: Gephyraulus raphanistri

29a Young or often well-developed shoots ± shortened and slightly swollen over their complete length, or with ± expanded often pale green swellings causing conspicuous curving. Galled siliques sterile or ± early bursting => 30

29b Ovaries, sometimes also calyx leaves and stamens, conspicuously disfigured, enlarged, with white at first closed, soon dusty sori. B. juncea, napus, nigra, oleracea, rapa: Albugo candida

30a Larvae white, only rarely pale yellow later on, non-jumping, usually many per silique. B. napus, oleracea, rapa: Dasineura napi

= Fruit galls, occasionally recorded from literature for Ceutorhynchus assimilis or for larvae of unidentified snout beetle, might also be attributed to this midge

30b Silique swollen, contains a single orange midge larva. B. nigra: Asphondylia stefanii

gallers on Euphorbia

pub 5.xii.2019

Dichotomous table for gallers on Euphorbia

by Hans Roskam

1a On parts above ground => 4

1b On subterranean buds, shoots or roots => 2

2a On buds or stems => 3

2b Roots with small nodular or slender spindle-shaped swellings, up to 6 mm long. E. peplus, cyparissias, helioscopia: Meloidogyne hapla

3a Underground part of usually severely stunted shoot axis often with already on rhizome with an up to about 10 (12) mm long and 4 (6) mm broad, acorn- to spindle-shaped, rough-walled swelling. The terminally situated shoot is severely stunted and soon shrivelling. Containing in the widened pith a compact, cylindrical maggot with black pharyngeal skeleton; puparium later on dark brown. E. cyparissias, amygdaloides: Pegomya euphorbiae

3b Underground stem with large swelling that incorporates leaf buds; cavity inside with a maggot or puparium. E. cyparissias, esula, amygdaloides: Pegomya argyrocephala

4a Expanded malformations on shoots, soon bearing fruiting bodies of fungi => 15

4b Malformations caused by animals => 5

5a Galls on flowers or inflorescences => 13

5b Malformations on vegetative parts => 6

6a Galls only terminally on main- or side shoots, or on axillary buds => 9

6b Malformations on leaves or on expanded shoot parts => 7

7a On several organs of shoot => 8

7b Margin of leaf blade rolled inwards. E. nicaeensis: Unidentified gall midge

8a All terminal leaves of a shoot, also entire plants ± twisted spirally, loosely rolled upwards and inwards, discoloured yellowish or reddish; terminally sometimes clustered into loose tufts. E. amygdaloides, cyparissias, epithymoides, esula, peplus, palustris: Eriophyes euphorbiae

= The gall mite Phyllocoptes euphorbiae causes malformation of apical shoots of E. cyparissias, salicifolia

= The gall mite Aculops euphorbiae on E. spinosa causes drying of apical plant parts, buds and flowers

= The gall mite Eriophyes septemlineatus causes drying and malformation of terminal growth points and inflorescences on E. dendroides

= On E. glabriflora, amygdaloides, capitulate, serpentini the gall mite Aculops glabriflorae causes shortening and drying of vegetative growths and deformation of the inflorescence, and on E. myrsinites the gall mite Aculops montenegrinus causes similar malformations

8b Malformations caused by thrips on leaves of E. cyparissias, esula subsp. tomassiniana, myrsinites: Anaphothrips euphorbiae

8c Plants often severely stunted, infected stems, and other parts swollen, spongy ± distorted. E. helioscopia: Ditylenchus dipsaci

8d Minor swelling of twigs. E. characias: Thamnurgus characiae

8e Similar gall. E. amygdaloides, characias: Thamnurgus varipes

9a Leaves not connate, terminally clustered into a globular or elongated, ± bud-like tuft => 10

9b Upper 2–7 leaves connate forming a capsule-like gall; up to 15 mm long and 10 mm thick, sometimes rotund, usually oblong, pear- or bottle-shaped. Wall striate and hard. In smaller forms also on axillary buds as well as in inflorescences. Larvae orange-coloured to vivid red. Euphorbia spp.: Dasineura capsulae

10a Many leaves strongly broadened; curved over their complete length, tips converging towards gall, making a rotund, ± compact gall => 12

10b Tuft of leaves more loose and oblong, composed of several to many leaves; these with erect or sometimes ± deflected terminal part => 11

11a Tuft up to 30 mm long and 7 mm thick, consisting of 4–5, almost pod-like converging leaves. Sometimes also the following 2–3, ± spreading leaves similarly curved. Containing a single pale orange-red larva. Euphorbia spp.: Dasineura schulzei

11b Similar loose tuft gall; mainly known from Italy; very rare. E. esula: Spurgia esulae

12a Galls compact and ± globular, up to 10 mm across, yellowish-green, often conspicuously reddened; usually containing many orange-red larvae. Euphorbia spp.: Spurgia euphorbiae

= Similar galls on E. cyparissias may contain inquilinous white midge larvae: Macrolabis lutea

12b Terminal gall consisting of short leaves, thickened, leather-like, enveloping one another at base and making a rosette in their terminal half. Containing several yolk-coloured larvae. E. characias: Janetiella euphorbiae

13a Galls bud- or capsule-like => 14

13b Development of inflorescence ± stunted. Flowers disfigured, unopened or ± greened and leafy (phyllanthy). E. amygdaloides, cyparissias, epithymoides, esula, peplus, palustris: Eriophyes euphorbiae

13c Generative shoots stunted. Flower peduncles are partially shortened; variously clustered. Euphorbia spp.: Philaenus spumarius

13d Malformations of the flowers and the shoot tips. E. characias subsp. wulfenii: Aceria dalmatina

14a Gall capsule-like, up to 7 mm long and 5 mm broad, spindle-shaped or ± globular; laterally closed, often curved, with ± beak-shaped tip. Contains orange to vivid red larvae. Euphorbia spp.: Dasineura capsulae

14b The fruit is disfigured, ovoid, pea-size. E. boissieriana, cyparissias:
Dasineura euphorbiarum

14c Both bracts enlarged, inflated, compactly adpressed against each other, enclosing the aborted or disfigured flowers. Gall globular, similar to flower bud, up to 6 mm long. E. aleppica, esula & subsp. tommasiniana, falcata, nicaeensis, seguieriana: Euphorbomyia loewii

15a Malformation with brown to black sori, often together with spermogonia. Species complex of Uromyces scutellatus => 19

15b Malformations bearing yellowish sori of aecia and spermogonia; many species also subsequently develop the brown to blackish other spore forms => 16

16a Single or several shoots of the non-flowering plants are disfigured => 17

16b Malformation restricted to ± extensive parts of terminal shoot. Diseased shoot parts usually conspicuously elongated, lankier than normal ones and non-flowering. Leaves shortened, thickened, slightly broadened, pale-green; at first bearing pleasant smelling, later on stinking spermogonia; after a longer period the scattered aecidia-like sori develop on the underside. E. amygdaloides, carniolica: Endophyllum euphorbiae-silvaticae

17a Apart from the aecia and spermogonia bearing mycelium, other spore forms are also developed. Fungus monoecious => 18

17b Only aecia and spermogonia. Shoots, at first ± growing ahead, rigidly erect, abnormally elongated; exceptionally severely stunted; sometimes producing branched inflorescences with disfigured flowers. Leaves usually shortened, broadened, thickened and ± pale-green; with scattered aecia on the underside and spermogonia partially also on upper side. Fungi host alternating. Euphorbia spp.: Uromyces tuberculatus species complex

18a On E. exigua, nicaeensis subsp. glareosa: Uromyces tuberculatus

18b On many other Euphorbia spp.: Uromyces proëminens

19a On species of the subgenus Esulae => 22

19b On species of the subgenus Helioscopia => 20

20a On E. angulata, dulcis: => 21

20b On E. exigua, nicaeensis subsp. glareosa: Teliospores with minute, hardly visible warts. Uromyces tuberculatus

21a On E. angulata. Wall of teliospores densely reticulate: Uromyces bresadolae

21b On other Euphorbia spp.: Wall of teliospores delicately reticulate: Uromyces scutellatus

22a On Euphorbia species with glabrous seed coat => 23

22b Mainly on E. nicaeensis & subsp. glareosa, also on E. agraria, macroclada, petrophila. Teliospores with densely arranged very delicate warts. Uromyces sublevis

22c Mainly on E. falcata, also on E. dracunculoides subsp. glebulosa. Teliospores with coarse warts: Uromyces winteri

23a Infected leaves distinctly disfigured => 24

23b Diseased shoots hardly differ from healthy shoots. Infected leaves usually distinctly longer than normal ones. Telia bearing small warts, only visible under high magnification. E. cyparissias: Uromyces alpestris

24a Leaves on diseased shoots usually shorter and sometimes distinctly broader than those on healthy plants => 26

24b Leaves on diseased, usually elongated shoots, usually hardly disfigured. On E. seguieriana and close relatives => 25

25a Teliospores completely glabrous. E. nicaeensis, seguieriana: Uromyces laevis

25b Teliospores bearing loosely arranged small warts. E. barrelieri subsp. thessala, hyberna, macroclada, nicaeensis incl. subspp. glareosa & stepposa, seguieriana: Uromyces tinctoriicola

25c Teliospores with coarse, often coalescing warts. E. petrophila, seguieriana: Uromyces cristulatus

26a Wall of teliospores with ridges of varying length; apically provided with a distinct papilla. E. boissieriana, cyparissias: Uromyces striolatus

26b Teliospores bearing large, coarse, irregularly margined warts; apically lacking papilla. E. agraria, cheiradenia, cyparissias, esula incl. subsp. tommasiniana, exigua, lucida, nicaeensis incl. subspp. glareosa & stepposa, peplus, salicifolia, seguieriana, verrucose: Uromyces scutellatus

26c Wall of teliospores provided with small but distinct warts; apically bearing a papilla. E. cyparissias, esula: Uromyces kalmusii

gallers on Vicia

pub 3.xii.2019

Dichotomous table for gallers on Vicia

by Hans Roskam

1a On parts above ground => 5

1b On roots or root collar => 2

2a On roots => 3

2b Conspicuous proliferations on root collar or stems. V. faba, villosa, etc.: Agrobacterium tumefaciens

= The bacterium Rhodococcus fascians may cause “leafy galls” on V. faba

3a Roots with nodular swellings or laterally inserted nodules => 4

3b Roots on the outside not distinctly changed; temporarily bearing poppy-seed sized, lemon-shaped, white, soon brown cysts. Giant cells develop inside. Vicia spp.: Heterodera goettingiana and/ or Heterodera trifolii

4a Roots with nodular- or slender spindle-shaped to cylindrical swellings, up to about 6 mm long, bearing some lateral roots. Vicia spp.: Meloidogyne hapla

4b Rotund or cylindrical, about 2–7 mm long or compact, apically broadened, also forked or comb-like to coralloid subdivided nodules, which are inserted with narrowed base into main- and adventitious roots. Vicia spp.: Rhizobium leguminosarum

5a On inflorescences, flowers or fruits => 38

5b On vegetative parts => 6

6a Stem with localised swellings, spindle- to bulge-like or young plants at base conspicuously stunted and spongy, thickened => 32

6b Malformation of many organs terminally on shoots, or galls on leaves => 7

7a Expanded parts of shoots etiolated; internodes elongated; leaves ± reduced in size, usually paler, or internodes and leaf axis ± shortened, slightly thickened; leaf blades reduced. Malformations soon bearing fruiting sori at surface => 27

7b Malformations on single or many, normally inserted or ± clustered leaves; caused by animals => 8

8a Galls on separate leaves or on ± largely unfolded leaf blades => 9

8b Leaf completely disfigured; midrib hypertrophied; leaflets folded, pod-like Containing several orange-coloured larvae. V. angustifolia: Dasineura vicicola

8c Shoot tip distinctly stunted; the very young, hardly developed vegetative or generative organs largely stunted, swollen. Marginal leaves sessile, all basal parts strongly swollen, the peripheral leaflets increasingly developing, leaf blades rolled over their complete length or with unfolded tips only. Larvae white, non-jumping. V. sepium: cf. Dasineura viciae

8d Folded hypertrophied discoloured leaflets; contain yellow, 3 mm long midge larva. Vicia lutea: Anabremia trotteri

9a On petioles, midrib or on midrib of unfolded leaflets => 26

9b On leaflet leaf blades => 10

10a Galled leaflets conspicuously fleshly thickened. In early infestations usually all leaflets of several, clustered leaves disfigured. On older leaves only a few leaflets are galled => 23

10b Leaves not fleshly swollen; curled, curved, folded or rolled inwards => 11

11a Leaf curls or -rolls caused by aphids or spittlebugs => 19

11b Leaf folds, -rolls, curvings caused by midge larvae, thrips or mites => 12

12a Folds or rolls caused by midge larvae => 16

12b Malformations caused by gall mites or thrips => 13

13a Mite galls => 14

13b Plant largely atrophied and distorted; leaflets smaller, irregularly constricted and curved, locally discoloured or browned; ± upwardly folded or -rolled. Plant largely atrophied and distorted; leaflets smaller, irregularly constricted and curved, locally discoloured or browned; ± upwardly folded or -rolled. V. cracca, hirsuta, pannonica, sativa, sparsiflora, tenuifolia, tetrasperma, etc.: Firmothrips firmus

= Stunting of various parts is occasionally caused by the black-brown “pea thrips”: Kakothrips robustus

14a Malformations on species with tendrils => 15

14b On V. cassubica, sepium. Leaflets upwardly folded, bent, petiole ± twisted. Unidentified gall mite

15a Leaf blade of leaflet, mainly of apical leaves, rolled upwards from margin up to midrib, ± curved and deflected. V. angustifolia, cracca, sylvatica, tenuifolia, villosa: Aculus retiolatus

15b Similar malformations on V. hirsuta, tetrasperma: Aceria trifolii

16a Leaf blades of single or all leaflets folded, pod-like, over the midrib or occasionally rolled inwards; not conspicuously thickened. On glabrous Euvicia species => 18

16b Similar galls on ± pubescent species. V. villosa, cracca, hirsuta => 17

17a On V. cracca, villosa, incl. subsp. varia. Fold only slightly thickened. Larva pale flesh-coloured: Anabremia massalongoi

17b Single leaflets of mostly unfolded leaves rolled upwards over the midrib on both sides. Leaf blades not shortened. Gall wall hardly thickened, at first usually not discoloured-, later on often yellowish to brownish. Larvae pale yellow to pale orange-yellow. V. cracca: Tricholaba viciarum and/ or Tricholaba similis

17c On V. hirsuta. Leaf blade folded together upwards with only its midrib thickened. Unidentified gall midge

18a Single to several leaflets per leaf loosely bent upwards. Leaf blades almost normally developed, hardly thickened and discoloured. Larvae white to dull yellow. V. sylvatica: Lathyromyza sp.

18b On V. cassubica, dumetorum, pisiformis. Single or several leaflets of younger leaves folded upwards, only the midrib thicker and discoloured. Galled parts drying after departure of the larvae, causing the unaffected leaf blade parts to be distorted ± sickle-shaped. Unidentified gall midge

19a Malformations caused by aphids => 20

19b Leaf blades usually with several deflected, ± clustered nest-like on the stunted, also curved axis; locally strongly curled and discoloured deep-green. Vicia spp.: Philaenus spumarius

20a Aphid black => 21

20b Aphid dark-green; of considerable size; siphunculi club-like, black, like cauda and legs. V. sativa, sepium, etc., occasionally on V. faba: Megoura viciae

21a On narrow-leafed Vicia species => 22

21b On V. faba; especially at shoot tips, often occurring in large colonies; causing only stunting, no gall-like malformations. Aphid up to about 2.5 mm long, dull-, rarely brown-black: Aphis fabae

= Bulging of leaves may also be caused by Vicia-virus 1.

22a Aphid up to about 2.75 mm long, black, appearing bluish translucent through white powdering; antennae longer than half the body length; siphunculi and the about equally long oblong cauda black. V. cassubica, cracca, Paederota lutea, Vicia pannonica, tenuifolia, tetrasperma, villosa: Aphis craccae

22b Aphid variating in size; black. Froth-covered nymphs only slightly frosted. Apterous adults with glossy back. Siphunculi longer than cauda, black. V. cracca, faba, sepium, etc.: Aphis craccivora

23a Galls on V. sylvatia, cassubica => 25

23b Galls on other vetches => 24

24a Leaflets folded upwards, pod-like. Wall succulent thickened, ± discoloured, also reddened. Often on severely stunted, terminal- or lateral shoot tips already the youngest leaves become galled and clustered into conspicuous balls, up to even 30 and more mm long; in other cases unfolding leaves have been attacked and several to all, usually distinctly shortened, leaflets have sometimes been transformed into clustered, thick-walled pod-like galls. Containing several white, later on proximally ± pink-coloured larvae. Mainly on V. sativa, sepium and other related Euvicia species: Dasineura viciae

= Also Anabremia bellevoyei has been reported as causer of disfigured leaflets, but this species is inquilinous like all other Anabremia species

24b Galls similar. Larvae pale-red. V. cracca, hirsuta, tenuifolia, tetrasperma, villosa, etc.: Dasineura loewiana

24c Similar galls on various Vicia species; containing whitish-yellow larvae: Dasineura spadicea

= Inquiline of D. viciae, loewiana and spadicea: Macrolabis vicicola

25a On V. sylvatica. Unfolding young to almost full grown leaves all or only several leaflets are transformed into strongly cartilage-like thickened, pod-like galls, in cross section almost rotund, usually pale-green. Containing a single or several larvae white to yellow at maturity: Tricholaba viciobia

= Inquiline gall midge: unidentified Macrolabis sp.

25b On V. cassubica. All leaflets of one or more youngest, already isolated or unfolding leaves folded upwards, pod-like. Complete gall wall conspicuously thickened, ± discoloured or reddened. Containing several milk-white, non-jumping larvae. Unidentified gall midge

26a Up to 10 (15) mm long, spindle-shaped, thin-walled swelling with oblong larval chamber on petioles or midrib. Containing a single larva. V. cracca, ? villosa, incl. subsp. varia, dumetorum, sylvatica: Cyanapion gyllenhalii

26b Midrib weakly swollen. V. sepium: Apion sp. s. lat.

27a Infected parts, especially on leaf underside, with expanded, ± grey-white patches of branched conidiophores. Malformations almost only caused by systemic infection, partially etiolated, partially associated with shortening of diseased organs => 29

27b Malformations caused by rust fungi => 28

28a Aecia and spermogonia loosely distributed over underside of leaf; mycelium often completely pervading the ± disfigured plant; leaves conspicuously smaller and shorter, pale-green. V. onobrychioides: Uromyces valesiacus

28b Fungus repeatedly developing aecia. Spermogonia only occurring together with primary aecia. Secondary aecia cup-shaped with slightly bent margin; in small groups with 2–5 on sometimes weakly galled pads on stems or scattered on expanded, usually not disfigured parts on undersides of leaves. V. hirsuta, more rarely V. tetrasperma: Uromyces ervi

29a On several Euvicia species => 30

29b On V. hirsuta, lathyroides, tetrasperma: Peronospora ervi

30a On V. cracca and forms, resp., on V. sepium => 31

30b On V. angustifolia, sativa, villosa: Peronospora viciae

31a On V. cracca: Peronospora mayorii

31b On V. sepium: Peronospora viciae

32a Stem with tough-walled or spongy swellings, containing gall causers => 33

32b Stem on any area, mainly close to ground, with broad spindle-shaped to bulging swellings, which bear single, or several rimmed depressions on the surface, containing froth-covered nymphs. Vicia spp.: Planchonia arabidis

33a Stem, also inflorescence stalks and -midrib, sometimes also leaf axis, with slender spindle-shaped, thin-walled, often at first pale-green coloured, large-chambered swellings; containing beetle larvae => 34

33b Seedlings severely stunted. Internodes stunted, sometimes twisted, often distinctly swollen. Gall tissue spongy, necrotic. Similar infestation ± encroaching into petioles and midrib; leaflets disfigured. Swellings often one-sided, curved, wrinkled, bulging, yellowish or reddish, irregularly arranged over the internodes. V. cracca, faba, hirsuta, pannonica, sativa, tetrasperma, villosa: Ditylenchus dipsaci

34a Swellings elongate spindle-shaped, usually slightly protruding => 36

34b Galls distinct, middle parts about twice as thick as the normal organ; elongate at the internodes, more compact on nodes; about 7–10 mm long. Containing a larva with a small head capsule => 35

34c Internodes with expanded, slender swellings, about 15–25 (35) mm long, reaching twice the organ diameter. The pith, which is excavated over a length, containing a compact white maggot with black gullet: cf. Agromyza erythrocephala

35a On V. cracca, dumetorum, hirsuta, sepium, sylvatica, tenuifolia, tetrasperma, etc.: Cyanapion gyllenhalii

35b Similar galls on V. cracca: Catapion seniculus

36a Galls usually differing from the previous ones by their small size, however, not positively distinguishable without rearing of adults. V. pyrenaica, sativa subsp. nigra => 37

36b V. angustifolia, lathyroides, sativa, sepium, tenuifolia, parviflora, villosa: Apion sp. s. lat.

37a V. sativa subsp. nigra: Holotrichapion pullum subsp. aestimatum

37b V. pyrenaica, ? V. sativa, sepium. Swelling of node, about 2 mm broad, 7 mm long; inconspicuous: Holotrichapion aethiops

38a On fruits => 44

38b On inflorescences or flowers => 39

39a Malformation of the complete inflorescence or localised galls on its stem parts only => 40

39b Unopened flowers contain several white, eventually orange-coloured jumping midge larvae. V. cracca, cassubica, tenuifolia, villosa, incl. subsp. varia, etc.: Contarinia craccae

= White larvae of Ametrodiplosis viciae, living on V. cracca, belong to an inquiline of Contarinia craccae

= White larvae of Jaapiella sp. are developing together with Contarinia craccae in flower heads of V. cracca

= Orange-yellow larvae of Anabremia viciae, recorded from flower buds, are inquilines of an unidentified gall midge

40a Malformations extending over inflorescence => 41

40b Spindle-shaped, up to 15 mm long, usually yellowish-green swelling on inflorescence stalks or rachis. Containing a single larva. V. cracca, hirsuta, sylvatica: Cyanapion gyllenhalii

41a Inflorescence and flowers stunted, ± clustered, ball-like => 42

41b ll flowers of a raceme ± greened and leafy. V. hirsuta, tetrasperma: Aceria trifolii

= On V. cracca and especially V. villosa inflorescences occasionally with all flowers, usually on many racemes, variously disfigured and partially greened by viruses

42a Gall midge larvae occur between organs on stunted shoot tips => 43

42b Inflorescences and shoot tips clustered into balls of flowers, or leaves. Aphids almost black, appearing bluish because of the white powdering; also encroaching onto stems. V. cracca: Aphis craccae

43a hoot tips distinctly shortened. All inserted organs clustered into conspicuous, ± dense balls. Flower primordia, situated between young leaves with pod-like disfigured leaflets, largely stunted, variously swollen and unopened. Only exceptionally normally coloured. Within and between organs are many white larvae. V. angustifolia, sativa, sepium: Dasineura viciae

43b Axial parts of inflorescence distinctly stunted. Buds clustered into rotund, more pubescent balls; unopened or only slightly opened. Yellow larvae present between buds and rachis. V. sepium: Unidentified gall midge

44a Pods disfigured by midge larvae => 45

44b Locally variously distinctly swollen pods containing a larva with narrow head capsule. V. cracca: Apion sp. s. lat.

46a Galls on Vicia species developing tendrils => 47

46b Galls on erect Vicia species => 46

46a Pods often completely or slightly disfigured, at their surface bumpy to sometimes undulately, curved. Containing several jumping, white larvae. V faba, ? angustifolia, ? sativa: Contarinia sp.

46b Pods disfigured; locally more swollen and with mycelium inside. Containing a larva at first pale-yellow, later on orange-coloured. V. sepium: Asphondylia lathyri

47a Pod of V. hirsuta, sylvatica etc. locally distinctly swollen. Inner wall of gall with mycelium. Containing a pale- to yolk-yellow larva: Asphondylia ervi

47b Ditto on V. cracca. Containing white larvae: Asphondylia sp.

gallers on Ribes

pub 2.xii.2019

Dichotomous table for gallers on Ribes

by Hans Roskam

1a On inflorescences, flowers or fruits => 28

1b On vegetative parts => 2

2a On parts above ground => 3

2b Roots with spindle-shaped to nodular swellings, usually bearing some side roots. R. rubrum: Meloidogyne hapla

3a On buds or leaves => 11

3b On shoot axis => 4

4a On higher parts => 6

4b On root collar => 5

5a Nodular to walnut-, sporadically chicken egg-sized proliferations on root collar, tuberculate on surface, at first white, succulent, later on browned and woody; galls sometimes also on larger roots close to surface and on higher situated stem parts. R. rubrum, uva-crispa: Agrobacterium tumefaciens

5b Excessive branching at stem base; shoots only a few cm long, strongly succulent, variously striate, with disfigured stump-like branchings. R. uva-crispa: Rhodococcus fascians

6a Causer not occurring on gall surface => 8

6b Younger axial parts usually with many rotund- to oblong-oval pock-shaped swellings, which contain a flat causer in a rimmed depression => 7

7a Scale ± rotund; 1.2–1.6 (1.8) mm wide, dirty to brownish-grey, flat arched, with dark yellow central area. Froth-covered nymph red, mainly harmful on R. nigrum: Epidiaspis leperii

7b Scale pear-shaped, white to grey-white, up to about 2.5 (3.0) mm wide. Female wine-red. Ribes spp.: Chionaspis salicis

7c Sporadically recorded on R. alpinum, R. rubrum, R. uva-crispa: Viscum album

8a Swellings on thin axial parts, elongate, ± spindle-shaped, often inconspicuous. Caused by insect larvae boring inwards => 10

8b Conspicuous, nodular or bulging or almost witches’ broom-like malformations => 9

9a Branches, more rarely stems, with warty-nodular, usually several burr tubers. R. uva-crispa, less frequently on R. alpinum, aureum, rubrum and other Ribes species: Inducer unidentified – ? bacterium, fungus; may partially be caused by: Agrobacterium tumefaciens

9b Cauliflower-like proliferations, occurring mainly on root collar. R. uva-crispa: Rhodococcus fascians

= Sporadically witches’ broom-like malformations have been associated with the rust fungus Cronartium ribicola; aecia develop on Pinus strobus, non-cecidogenic, Uredinia and telia developing mycelium in protruding cylinders clustered on leaf underside of several Ribes species

10a Inconspicuous oblong swellings of bark, mainly visible in autumn, on young axial parts. Older larvae boring in spirals in inner bark. Rare on R. nigrum: Agrilus cuprescens

10b Similar swellings on young woody shoots; older larvae feeding in pith; whitish with dark dorsal band and brown head. Ribes spp.: Synanthedon tipuliformis

10c Midge larvae live gregariously under bark. The bark is peeling off, sometimes accompanied by a dying back of the top shoots. R. nigrum: Resseliella ribis

11a On leaves => 12

11b Young side-, also apical buds distinctly swollen, producing ‘big buds’. Infestations especially conspicuous in spring, because diseased buds only partially open, and do not unfold. R. alpinum, nigrum, rubrum, rarely on R. uva-crispa: Cecidophyopsis ribis

11c Similar terminal or lateral big buds on R. rubrum: Cecidophyopsis selachodon

= The gall mite Colomerus riberini causes silvery white erineum on the underside of the leaf of R. nigrum, and the gall mite Cecidophyopsis grossulariae causes foliar injury, cavities at vein bases, enations on leaf disk, discoloration. R. nigrum, rubrum, uva-crispa

= Leaf buds of R. alpinum swollen to almost one cm in diameter, do not unfold; caused by the gall mite Cecidophyopsis alpina. Similar swollen leaf buds of R. aureum are caused by the gall mite Cecidophyopsis aurea

12a Curls, archings or bladder -shaped swellings caused by aphids => 19

12b Expanded folds, rolls, curls, or abnormal pubescence or localised warts and bulges caused by other parasites => 13

13a Localised swellings by rust fungi => 17

13b Malformations caused by animals => 14

14a Expanded malformations => 15

14b Leaf margin with several egg capsules, soon necrotic after emergence of larvae (procecidia, oviposition scars, not true galls). R. rubrum, uva-crispa: Pristiphora appendiculata

= The yellow gooseberry sawfly Nematus ribesii lays her eggs like pearls on a string along the veins without development of procecidia (oviposition scars, not true galls).

15a Leaf folds or rolls caused by midge larvae; galls lacking additional pubescence => 16

15b Leaf blade often severely disfigured, curved, folded, irregularly hunchbacked, rolled at margins, ± abnormally haired. R. alpinum, aureum: Aceria scaber

15c Less protruding, slight bladder-like archings on leaves of R. uva-crispa: Cecidophyopsis ribis

16a On R. nigrum. Margins of still unfolded leaves ± funnel-shaped to rolled, screw-like; margins of older leaves rolled over upwards to varied extent, also folded. Leaf blade curled. Spaces in between with several, at first whitish, then yellowish or yellow larvae: Dasineura tetensi

16b Similar malformations on other Ribes species. Rolls, especially on younger, developing leaves; on many hosts more densely covered with elongate, ± hair-like structures. Assignment of causer insufficiently known. Unidentified gall midges:

a On R. alpinum: Causer questionably assigned to Dasineura tetensi.

b On R. petraeum; Folds ± thickened and reddened. Abnormal grey to brown pubescence. Containing several white midge larvae.

c On R. rubrum: several white midge larvae. “Asphondylia ribesii”. Furthermore Stroblophila aberrans which does not induce galls

d On R. uva-crispa: Leaf blades partially abnormally pubescent, containing several midge larvae, at first milky-white, eventually pale yellow are attributed to Dasineura tetensi

17a Pads or bulges bearing yellow to orange-coloured aecia => 18

17b Rotund, sometimes joined, chestnut-brown, yellowish margined weak pads, usually protruding on upper side of leaves, with 2-celled, wart-like teliospores. Frequently also on fruits. R. alpinum, nigrum, petraeum, rubrum, uva-crispa, etc.: Puccinia ribis

18a Swellings minor, almost only on main veins, with joined sori. Aecia lacking peridium, dusty, belonging to the species complex of Melampsora ribesii-viminalis

18b Similar on many Ribes species: Melampsora epitea

18c On several Ribes species also develops: Melampsora epitea var. epitea

18d Swellings always distinct, protruding on leaf underside, usually rotund, up to 10 mm across, yellowish, on upper side often red margined; developing on petioles, young stems and midrib of racemes, oblong, sometimes much larger bulges; young fruits sometimes largely covered. Aecia with cup-shaped opening peridium; often ± circularly arranged on the galls. Ribes spp.: Puccinia ribesii-caricis

19a Leaves ± rolled, curled or weakly arched; often clustered, nest-like, on shoot tips => 21

19b Leaf blades often with several, conspicuous, larger or smaller, yellowish, often deep-red speckled, strongly to broad bladder-like swollen, open, upward archings => 20

20a On R. alpinum: Cryptomyzus korschelti

20b Galls mainly on R. rubrum, rarer on R. nigrum, petraeum, spicatum, uva-crispa and others, also on many cultivated foreign species: Cryptomyzus ribis

21a Disfigured leaves densely clustered, nest-like, on severely stunted shoot tip. Wingless aphids dull on surface, antennae about half the body length => 27

21b Disfigured leaves on often only slightly shortened shoots clustered in nests, or situated distally. Body of wingless aphids glossy, antennae always longer than half the body length, often even longer than the whole body => 22

22a Aphids with club-shaped siphunculi => 23

22b Aphids with cylindrical siphunculi. 2–3 mm, pale-green to green. Siphunculi pale with darker tip, about twice as long as cauda. Antennae of fundatrixes shorter, of fundatrigenia slightly longer than body. Leaves only weakly arched and not discoloured. R. alpinum, nigrum, rubrum, uva-crispa, etc.: Nasonovia ribisnigri

23a Aphid differing from all other aphids on Ribes by its dark brown body. Leaf blades of basal leaves narrower, woody, shaded shoots disfigured, discoloured, soon dropping. R. nigrum, rubrum: Rhopalosiphoninus ribesinus

23b Aphids of different colour => 24

24a Adults with expanded brown to black dorsal pattern. Mainly on seedlings, rolling the brittle leaves but not discoloured, often developing dense nests of leaves. Aphid 2.7–3.1 mm; basic colour green. Tibiae, siphunculi and cauda black. R. rubrum: Hyperomyzus rhinanthi

24b Dorsal body part of apterous aphids lacking pigmentation, or with only minor pigmentation. Siphunculi of apterous aphids pale coloured => 25

25a Aphids pale yellowish-green, difficult to distinguish and only by microscopical examination => 26

25b Aphid green. Leaves ± rolled over their length, also arched; sometimes in loose nests. Venation yellowed or leaf blades yellowing, mosaic-like. Ribes spp., especially on R. nigrum: Hyperomyzus lactucae

= Similar malformations are caused by viruses.

26a Leaves arched, in loose nests. Aphid 2.5 mm long, glossy, pale yellowish-green, siphunculi pale, sometimes darker in the middle and at their tip, rather strongly swollen. Antennae about as long as body. R. alpinum: Hyperomyzus picridis

26b Leaves weakly arched, yellowed at veins. Occasionally in loose nests. R. uva-crispa: Hyperomyzus pallidus

26c Disfigured shoot apices, petioles and curled leaves. Ribes spp.: Hyperomyzus zirnitsi

27a Leaves accumulated at tip, in dense nests. On all wild and cultivated forms of R. uva-crispa: Aphis grossulariae

27b Similar malformations and dense leaf nests on R. rubrum, also on R. alpinum, aureum, nigrum, sanguineum, etc.: Aphis schneideri

= Sometimes the polyphagous, never gall inducing, mite Bryobia praetiosa s. lat., appear as successoria (secondary inhabitants) in early vacated galls of various aphids. From spring onwards in many food plants, especially fruit, partially as important pest, because of suction damage on unfolding, early withering leaves.

28a On fruits => 32

28b On flowers or on inflorescences => 29

29a Flower galls => 30

29b Complete inflorescence disfigured. R. alpinum: Unidentified gall midge

= Various malformations associated with greening, on several flowers of a raceme of R. nigrum, are caused by virus

30a Flowers enlarged, unopened. R. alpinum, rubrum, uva-crispa => 31

30b Flowers transformed into globular- or pear-shaped, whitish or reddish galls. Corolla strongly swollen. Containing one or more yellowish or orange-red midge larvae. R. nigrum: Dasineura ribis

31a Base of calyx succulent, pale yellow to red; corolla and stamens hard. Larvae often gregarious, at first white, then yellow to orange-coloured. Galled flowers dropping after larvae complete development. R. uva-crispa: Contarinia ribis

= The N-Am gall midge Rhopalomyia grossulariae has been recorded on Ribes grossularia

31b On R. alpinum, rubrum. Flowers enlarged, unopened. Unidentified gall midge(s)

32a Galls caused by fungi => 34

32b Galls caused by insects => 33

33a Immature fruits variously disfigured, up to twice the normal size. Containing a single to five orange-coloured larvae. R. uva-crispa: Unidentified gall midge

33b Fruit strongly swollen or elongated and narrowed. R. nigrum: Pachynematus pumilio

34a Fruit wall often with several wart-like pads, a few mm long, on which the telia develop. Ribes spp.: Puccinia ribis

34b Infected fruits often bulging on expanded areas. Many aecia on pads. Sori occasionally also on fruit stalks and stalks of fruiting racemes. Ribes spp.: Puccinia ribesii-caricis

gallers on Pyrus

pub 1.xii.2019

Dichotomous table for gallers on Pyrus

by Hans Roskam

(Pyrus communis s. lat.; including cultivated pear, P. domestica, as well as P. communis subsp. achra and pyraster)

1a On above-ground parts => 4

1b On root, root collar or basal stem parts => 2

2a Malformation larger than 10 mm => 3

2b Root with nodular swellings. P. communis: Meloidogyne hapla

3a Roots, including the older ones, with cancer-like, and. buckled enlargements or rotund swellings. P. communis, nivalis: Eriosoma lanigerum

3b Root, root collar or also basal stem parts with hazelnut- to egg-size or even larger, tuberculate proliferations, which occasionally coalesce into voluminous complexes. P. communis: Agrobacterium tumefaciens

4a On flowers or fruits => 28

4b On vegetative organs => 5

5a On leaves or buds => 10

5b On lignified parts => 6

6a Predominantly on stem parts, occasionally on thicker branches => 7

6b On thicker branches, less frequent on stems, variously slightly spindle-shaped, swollen. From the galls develop: Viscum album

7a More or less open, rimmed cancer wounds on thicker branches => 9

7b Mainly closed cancers on shoot axis, especially on younger trees, or irregular depressions on bark of younger shoots => 8

7c Midge larvae cause woody, plurilocular galls on twigs. P. communis: Apiomyia bergenstammi

8a Bark of younger stems with irregular rimmed depressions, containing causer beneath a 1.2–1.6 (1.8) mm long, dirty-grey, rotund scale. P. amygdaliformis, communis and forms: Epidiaspis leperii

8b Occasionally also on Pyrus species in similar galls beneath a pear-shaped scale up to about 2.5 mm long: Chionaspis salicis

8c Local, according to the organ’s development, usually closed cancer-like proliferations, especially on stems of younger trees or on thinner branches. P. communis: Eriosoma lanigerum

9a Irregular, eventually open cancer wounds, developing from proliferations and thickenings of bark; sometimes containing several lepidopteran caterpillars eating bark and sapwood. P. communis: Enarmonia formosana

= The clear-wing moth Synanthedon myopaeformis, which lives mainly on apple is an occasional inhabitant of cancers, but do not cause them.

9b Expanded open cancer wounds caused by fungi: Neonectria ditissima

10a On leaves => 11

10b Buds transformed into a globular to conical, yellowish, multi-chambered, woody gall. If strongly infected, stunting of shoot and accumulation of galls into a larger, irregular clustering. Each chamber containing a single larva. P. communis, salicifolia, syraica: Apiomyia bergenstammi

11a Galls of indefinite shape. Leaf blade extended and variously disfigured; folded, ± irregular and without particular thickening, only loosely rolled inwards, variously bulging swollen or ± curled => 19

11b Gall constant, locally ± defined; narrow or tough marginal roll; callosity, pock, pustule, abnormal pubescence or local, strictly defined bulges => 12

12a Narrow, restricted to edge roll of margin or thick-walled upward roll of the complete leaf blade => 18

12b Gall formation on the leaf blade => 13

13a Bladder-like enlargement, bulges, pocks or pustules => 14

13b Felt-like, initially yellowish or reddish, later on brownish pubescence, mainly of leaf underside. Hairs long, cylindrical, blunt, bent. P. communis: Unidentified gall mite

14a Callosities, pucks or pustules => 15

14b Up to 10 mm broad, pale-, later on yellowish-green, soon blackening, upward arched bladders, single or in groups. At maturity of fungus densely covered with pink-coloured asci. Exceptionally also on floral parts. P. communis, especially cultivated-, less abundant on wild forms, also on P. amygdaliformis: Taphrina bullata

= Various archings of leaf might be caused by viruses.

15a Rotund to elongate spindle-shaped, yellowish to orange-red bulges, predominantly partially including the main venation. Rust fungi => 16

15b Initially yellowish, ± red tarnished, later on brownish to 5 mm broad, per leaf blade usually many, irregular pocks, protruding on both sides. Exit underside. The mites live in enlarged intercellular spaces of the swollen leaf parenchyma. Pyrus spp.: Eriophyes pyri

= Warts on the leaves, hollow on the underside are caused by the gall mite Eriophyes pseudoinsidiosus. They are the result of sucking damage to the leaf while still in the bud stage. P. communis

15c Translucent usually solitary pustules on the leaf blade or midrib, visible on both sides, vacated by eclosing larvae (procecidia: oviposition scars, not true galls): Pristiphora abbreviata

16a Swelling slightly arched. The cylindrical peridium of aecia developing from the bulge opens at apex and frays out. Telia on Juniperus communis etc. => 17

16b Swellings very distinct. Peridium of aecia egg- to cone-shaped. Unopened at apex, opening with longitudinal slits. Pyrus spp.: Gymnosporangium sabinae

17a Minor swellings. Aecia often hardly developed. Spores 19–26 x 19–22 μm. Gymnosporangium confusum

17b Swellings and aecia usually distinct. Spores 22–30 x 18–26 μm. Pyrus spp.: Gymnosporangium clavariiforme

18a Usually both leaf halves, tip excepted, from margin often to midrib rolled upwards. The rolled part arched, thickened, ± yellowed or reddened, soon browned. Galls predominantly on terminal leaves of suckers or young trees. Larvae often many, white or reddish. Pyrus spp.: Dasineura pyri

18b Similar galls on Pyrus salicifolia. Only one cream coloured larva develops in a gall. It is not clear if it is a gall causer or inquiline in galls caused by Dasineura pyri: Macrolabis pyricola

18c Leaf blades of extending leaves remain unrolled up to midrib. Containing a yellow black-headed larva. Pyrus spp.: Anthonomus spilotus

18d Upward roll narrow, compact, hardly thickened. Leaf blade sometimes darker discoloured. Pyrus spp.: Epitrimerus marginemtorquens

19a Malformations caused by aphids => 20

19b Malformations caused by psyllids or gall mites => 21

20a Leaf blade more or less stunted and browned, weakly rolled. Usually many leaves are infected on the ± stunted shoot tips. Pyrus spp.: Epitrimerus pyri

= Similar malformations are caused by thrips. Taeniothrips inconsequens lives on Pyrus and also in a similar way on other hardwoods

20b Leaves variously slightly to spirally deflected, curled and discoloured. Pyrus spp.:

a Cacopsylla pyrisuga ‒ The only psyllid harmful on pears.

b Cacopsylla pyricola – Galls similar, but facultative.

c Cacopsylla pyri – Gall-like malformations exceptional, only on young plant parts; infestation of older leaf blades results in spotting and browning of prematurely dropping leaves.

21a The disfigured leaves are ± uniformly distributed on the stunted shoot tip => 25

21b Infected leaves usually ± clustered at the shoot tip => 22

22a Aphids pale to dark-green or reddish-brown to brown. Apterous aphids powdered or dull; dorsal side at most with some pigmented spots => 23

22b Aphid black-brown with pale legs; apterous adults with dark pigmented glossy backs, grey powdered as froth-covered nymphs. Leaf roll very variable, in spring; midrib often circular-, spirally- or screw-like rolled. Leaf blades variously stunted, ± yellow marbled or discoloured. P. communis: Melanaphis pyraria

23a Aphids reddish-brown to brown, covered with wax powder => 24

23b Aphid leaf-green, lacking wax powder, with rather long dark siphunculi; on leaf underside and on shoots. P. communis: Aphis pomi

23c Occasionally observed as causer is: Rhopalosiphum oxyacanthae

24a Leaves loosely or strongly deflected; midrib contorted in loose spiral. Leaf- cluster loose; at latest vacated by end 5. Aphid yellowish-green, with dark-green, segmentally striated pattern on back, weakly grey-powdered. Producing red juice when crushed. Pyrus spp.: Dysaphis pyri

24b A very close aphid lives in similar ± triangular bag-like rolled malformations. Galls still inhabited in 7, 8; locally serious pest: Dysaphis reaumuri

25a Aphids green or brown. Leaves yellow; along the midrib almost bag-shaped, more rarely rolled-folded, ± marbled => 26

25b Aphids black. Leaves on the usually slightly stunted shoot tip spoon-shaped deflected and more strongly rolled at margin. On the shoot tips of seedlings or coppice. Aphis fabae

26a Immature alates produced by brown fundatrices => 27

26b Immature alates produced by green fundatrices, with a double row of dark green spots: Anuraphis farfarae

27a Galls indistinguishable from previous species: Anuraphis subterranea

27b In galls indistinguishable from previous species lives the presumably inquiline Anuraphis catonii

28a On fruits => 29

28b Flowers severely stunted. Corolla unopened covering the eaten inner parts. Containing a single larva. P. communis, amygdaliformis: Anthonomus pomorum

= Anthonomus piri deposits its eggs already in late autumn in flower bud primordia, larvae develop in early spring, destroying many flower primordia, however, without causing galls.

29a Infected fruits swollen calabash-like; initially significantly faster growing than normal ones; up to hazelnut size; hence distinguishable from the only half as large healthy ones. Often ± buckled, soon black-spotted, inside spongy, later hollow, then dropping. Containing gregarious larvae, white to pale yellow, jumping. P. communis, salicifolia: Contarinia pyrivora

29b Younger or older immature fruits with wart-shaped soft swellings, usually less than 5 mm across, occasionally coalescing, pale-green. P. communis: Eriophyes pyri

= Conspicuous, bump-shaped, hard fleshy swellings on the ± deformed fruits are caused by punctures of the bug Closterotomus fulvomaculatus

gallers on Malus

pub 30.xi.2019

Dichotomous table for gallers on Malus

by Hans Roskam

1a On above-ground parts => 3

1b On roots => 2

2a Rotund, cancer-like proliferations on roots and root collar, several cm long, at first glabrous on surface then ± bumpy, soon lignifying, laterally inserted, often many and variously coalescing. Especially on young plants. Malus spp.: Agrobacterium tumefaciens

2b Roots with nodular, rotund or oval swellings, up to about 7 mm long ± cracked or bulging, eventually bursting; close to ground level, even on older roots groups often coalescing, stimulated new tissue developing into voluminous cancer-like growths. Occupied by white woolly aphids. Malus spp.: Eriosoma lanigerum

2c Nodular, usually smaller, glabrous swellings. Malus spp.: Meloidogyne hapla

= The red bud borer Resseliella oculiperda damages rootstocks of cultivated roses and apples when these are grafted with scion buds by “shield budding”.

3a On leaves, buds, flowers or fruits => 7

3b On stems, branches and twigs => 4

4a Galls on or in the bark => 5

4b Expanded spindle- or club-shaped swellings on branches or stems. Malus spp.: Viscum album

= Witches’ broom-like malformations at the end of shoots are partially caused by virus diseases. The early developing malformations are distinguished by their discoloured leaves, which are longer stalked and have larger stipules than the normal ones.

= Cancer-like structures usually develop as excessive callus proliferations in over-sensitive responses. Also many wound-calluses may develop into smaller, similar, but locally depressed nodules.

5a Younger plant parts with nodular, or older ones with cancer-like proliferations of irregular nature => 6

5b Up to 2 mm long, lenticular, bulging-rimmed depressions on bark of young shoots, in case of heavy infestation slightly swollen. Each depression containing a red insect, covered by a ± rotund scale, 1.3–1.6 mm wide: Epidiaspis leperii

5c In similar, but deeper depressions on the swollen bark: Chionaspis salicis

6a Nodular swellings of bark, up to walnut-size, later on erupting and cracking; often many coalescing and developing expanded cancer-like swellings. Especially on young trees. Containing white powdered aphids in cracks. Spring to autumn. Malus spp.: Eriosoma lanigerum

6b Buckled margined cancer wounds, increasing on older branches and of very varied shape. At first, on younger parts, because of the strong regenerative ability of host, usually transformed into variously delimited, bumpy, ± closed, nodular tumours; later on, the central tissue decays on older branches resulting in fissured cancer wounds, open, into the wood: Neonectria ditissima

= Caterpillars of clear-winged moth Synanthedon myopaeformis or Enarmonia formosana are occasional inhabitants of cancers, but do not cause them.

= Also the sac fungus Neofabraea perennans has occasionally been reported as inducer of Nectria-like cancers on apple and pear.

7a On buds, flowers or fruits => 29

7b On leaves => 8

8a Malformations associated with various curls, swellings, folds or loose rolls, which often involve the complete leaf blades sometimes of many terminal leaves => 15

8b Narrow, compact marginal rolls or leaf blades with locally defined galls => 9

9a Narrow roll of leaf margin => 13

9b Pock-like or slightly bladder- to bulge-shaped galls, with erinea => 10

10a Pocks, bulges, or minor bladder-like swellings => 11

10b Irregular, initially reddish white, then brownish erinea, mainly on leaf underside, usually along venation. Hairs long, cylindrical, blunt, spiral. Mainly on M. sylvestris, less so on M. pumila, etc.: Phyllocoptes malinus

11a Malformations caused by fungi => 12

11b Leaf blades with many ± oval pocks, usually 2–4 mm across, protruding from both sides. M. communis, sylvestris, etc.: Eriophyes mali

11c Vagrant mites on the underside of the leaves. At high densities rusting may occur. M. domestica, pumila, sylvestris: Calepitrimerus baileyi

11d Translucent pustules, visible on both sides, soon collapsing, in 5, 6, usually on the midrib, are procecidia of the black pear sawfly, occurring mainly on pear, occasionally on apple. Pristiphora abbreviata

12a Yellowish pads rotund on leaf blade, ± spindle-shaped on midrib, protruding on underside, later on with oblong-cylindrical, often curved aecia. Peridium thread-like rupturing onto base. Malus spp.: Gymnosporangium tremelloides

12b Rarer on apple are the cylindrical, tuft-like aecia of Gymnosporangium cornutum

12c Minor, usually several per leaf blade, covered with ± radiating, blackish mycelium, rotund, up to 7 mm long upward archings on young leaves of hawthorn shoots. Malus spp.: Venturia inaequalis

13a Rolls of leaf margin lacking conspicuous pubescence => 14

13b Expanded, border-like upward rolls with abnormal pubescence, occasionally encroaching well into the leaf blade. M. sylvestris, etc.: Phyllocoptes malinus

14a Similar, but not conspicuously pubescent roll of leaf border. M. pumila, sylvestris: Eriophyes malimarginem-torquens

14b Leaves of young shoots with cartilaginous thickening, often on both margins, usually discoloured yellowish or reddish, often running parallel to midrib, usually resulting in an upward roll. Inside the brittle tube are several, at first cream-white, then red midge larvae. Malus spp.: Dasineura mali

= Inquilinous cream-coloured midge larvae living in galls of Dasineura mali: Macrolabis mali

15a Malformations caused by aphids => 19

15b Malformations attributed to other causes => 16

16a Malformations caused by mites, psyllids or spittlebugs => 17

16b Several terminal leaves on shoots stunted, disfigured, their margins ± bent upwards, slightly thickened and often completely covered by a sometimes cotton wool-like, white mycelium. Malus spp.: Podosphaera leucotricha

17a Malformations caused by mites or spittlebugs => 18

17b Leaves variously curled and deflected; with many small spots, soon turning brown, caused by suction feeding of flattened, yellowish to greenish froth-covered nymphs, up to 1.5 mm long, exuding copious honeydew. Malus spp.: Cacopsylla mali

17c Very similar infestation: Cacopsylla picta

18a Leaf blade stunted and soon browned due to many suction spots; in cases of severe infestation both halves are strongly folded upwards and their margins may even come in contact. Infected shoots die off prematurely. Malus spp.: Aculus schlechtendali

= Predating gall midges: Arthrocnodax mali, wissmanni.

18b Stems of saplings shortened. Leaves ± clustered and converging, leaf blades crumpled, locally deep-green. Containing a froth-covered nymph. M. pumila: Philaenus spumarius

19a Leaves folded along their midrib or rolled, distinguished by yellowish to reddish discolouration => 23

19b Rolls of margin or folds without particular thickenings => 20

20a Variously disfigured leaves are loosely inserted often on only slightly stunted shoot ends => 22

20b Shoot tip conspicuously shortened => 21

21a Many leaves on the ± stunted, curved and etiolated shoot tip are strongly deflected and ± curled. Dark-green aphids, ± 2 mm long, with long, dark brown-black siphunculi feed on underside of leaves and move onto shoots. Malus spp.: Aphis pomi

21b Similar galls, only inhabited in spring. M. pumila: Allocotaphis quaestionis

22a Downward leaf roll and curling caused by black aphids. M. pumila: Aphis fabae

22b Midrib of leaves sometimes loosely contorted. Leaf blades deflected downwards, often strongly rolled, making loose clusters; aphid yellowish-green with segmental dark-green striping dorsally and with dark siphunculi that are pale only at the tips. Malus spp.: Rhopalosiphum oxyacanthae

23a Leaves often crookedly rolled downwards on only one side, usually up to midrib, coarsely undulate at tip; discoloured yellowish or mainly intensively red => 24

23b Young leaves at shoot tip strongly rolled, often on both sides, almost intestine-like or ± spirally bent, discoloured yellowish. Often many young shoots infected; in which case the plants look bushy. Malus spp.: Dysaphis plantaginea

24a Aphid galls are usually vacated by end of June; galled leaves already drop in July => 25

24b Galled leaves stay on tree; also inhabited during summer. Malus spp.: Dysaphis devecta

25a The roll galls occurring on cultivated apple and relatives of the next aphids do not differ morphologically; the closely related aphids are only microscopically distinct; main difference is their host alternation. Furcula (mid-thoracic fork) of the wingless aphids is always bifid. Summer hosts are Polygonaceae, Apiaceae or Plantaginaceae => 26

25b Furcula not bifid. Summer hosts are Valeriana species. Malus spp.: Dysaphis brancoi

26a Aphid alternating to Apiaceae or Plantago => 27

26b Exules living on roots of Rumex and Rheum: Dysaphis radicola

27a Aphids alternating to Apiaceae => 28

27b Aphids migrating to Plantago: Dysaphis plantaginea

28a Leaf-roll galls in spring. Exules develop on Anthriscus. Malus spp.: Dysaphis anthrisci

28b Leaf-roll galls in spring. Exules develop on Chaerophyllum. Malus spp.: Dysaphis chaerophylli

28c Rolling and reddening the edges of the leaves. M. domestica and M. orientalis: Dysaphis chaerophyllina

28d Aphids living without host alternation, rolling and blistering leaves. Malus spp.: Dysaphis affinis

28e Rolling and reddening the lateral edges of the leaves. M. domestica and M. orientalis: Dysaphis armeniaca

28f Rolling leaves in E-Eu (North Caucasus, Crimea, Armenia) in spring, but the galls are yellow rather than red. Malus spp: Dysaphis brachycyclica

28g Rolled lateral margins of leaves in spring. M. domestica: Dysaphis flava

28h Rolling and reddening leaves. M. domestica: Dysaphis physocaulis

= Haplorhynchites caeruleus is galling the shoots of Malus sylvestris

29a On flowers or fruits => 30

29b The young caterpillar inhabits buds from 7, 8 onwards, feeds on these and tunnels in shoot during spring. Occasionally the bark reacts at infestation site with further development of conspicuous, sometimes cancer-like swellings. M. pumila: Blastodacna atra

30a On flowers => 31

30b Mainly apical half of infected fruits disfigured, knobbly: Dysaphis plantaginea

30c Scale of young fruits sometimes with many flat, ± pock-like swellings, up to ± 2.5 mm across, usually lighter coloured than surrounding tissue. M. pumila: Eriophyes mali

= Thrips flavus may be causer of distorted apples; not a true gall causer.

31a The corolla of infected buds does not open, but is closed and hood-shaped, at first reddish but soon browning and drying. Containing a single larva. Malus spp.: Anthonomus pomorum

31b Flower peduncle shortened, conspicuously thickened; corolla parts narrowed, variously disfigured, discoloured yellowish to greenish-white. All leaves of the diseased young shoots stunted, often bent upwards, spoon-like and with mealy dusting on both sides. Malus spp.: Podosphaera leucotricha

= Various anomalies of flowers, partially associated with greening, might be attributed to virus diseases.

gallers on Hieracium

pub 29.xi.2019

Dichotomous table for gallers on Hieracium and Pilosella

by Hans Roskam

1a On inflorescences or in the capitula => 23

1b On vegetative parts => 2

1c Proliferations on the base of terminal rosettes on stolons. Pilosella spp.: Aulacidea subterminalis

2a On leaves => 8

2b On shoot axial parts or tips => 3

3a On shoot axial parts => 5

3b On shoot tips => 4

3c All parts of shoot with white crusty blisters, very variable in size; shoot often distorted. Hieracium and Pilosella: Pustula obtusata

4a Rosettes with many variously enlarged and thickened leaves at their centres, externally with abnormally felt-like pubescence, the leaf margins or leaf blade often ± cone-shaped converging. Several, initially white- to cream-coloured, later red larvae. Pilosella spp.: Macrolabis pilosellae

4b Terminal leaves of lateral and main shoots swollen, folded upwards, making a fleshy pouch, with outside often ± villous pubescent; mid- and basal veins, sometimes also the neighbouring stem parts, thickened and discoloured. Larvae yellow-white. Hieracium spp., exceptionally on Pilosella: Macrolabis hieracii

5a Inducers inside the galls => 6

5b The inducers are in bordered, hollowed depressions in small bulging swellings, solitary or many Hieracium spp., less on Pilosella: Planchonia arabidis

6a Tough, broadly protruding galls caused by gall wasp larvae => 7

6b Slim stem swellings caused by eelworms Spongy swellings in the stem, predominantly on species of Pilosella. Tissue fragile and necrotic, lacking larval cavities. Ditylenchus dipsaci

7a Shoot with rotund or barrel-shaped swelling, up to 40 mm long, multilocular, initially green, later brown, ± occupied with stiff-bristly white hairs. One yellowish-white larva per chamber. On many species of Hieracium; sporadically also on species of Pilosella: Aulacidea hieracii

7b Irregularly shaped, multilocular swellings of the stem, 2–2.5 x 1.5 cm in size; the galls are hardly lignified and can easily be opened. They ripen in autumn; adults emerge in the following spring. Hieracium sp.: Diastrophus hieracii

7c Similar, but smaller, 4–10 mm long, uni/bilocular swellings in the upper part of the shoot, also at the base of the flower head or below the leaf rosettes on stolons. Pilosella officinarum: Aulacidea sp.

8a Malformation predominantly situated on the leaf blade or leaf margin, usually without involving the midrib, sometimes with abnormal pubescence => 12

8b Galls in petioles or midribs, sometimes ± extending into the leaf blade => 9

9a Inconspicuous, usually yellow margined, 2–3 mm long, 1 mm wide swelling on the midrib; covered with brown fungus spores => 11

9b Tough walled or spongy, loose, galls with animal inducers inside => 10

10a Long-oval to spindle-shaped, woody swelling, with large central chamber, on the underside of petiole or midrib; up to 3.5 mm long and 1.5 mm wide, ± yellowish. Often several galls, in various ways connate. Containing a single yellowish-white larva. Pilosella cymosa, echioides, flagellaris, floribunda, officinarum, onegensis: Aulacidea pilosellae

= Larvae of Dasineura nervicola cause egg-shaped swellings on the mid-vein of Pilosella lactucella, officinarum. Very rare.

10b Irregular, spongy, pale green or red tinted massive swellings of various size extending from petiole or midrib to the leaf blade. Hieracium and Pilosella: Ditylenchus dipsaci

11a On Hieracium spp.: Puccinia hieracii

11b On Pilosella spp.: Puccinia hieracii var. piloselloidearum

12a Malformations of the leaf margin, curls or abnormal pubescence => 16

12b Pustules, grooves or warts on leaf blade, sometimes only slightly changed => 13

13a Rotund pustules, up to 6 mm long, often rimmed, bulging on the upper side; usually a few to many per leaf blade => 15

13b Warts or small grooves => 14

14a Less than 1 mm long, yellowish gleaming or coloured warts on the underside of the rosette leaves, usually many and variously coalescing into crusts or into stripes the stems. Pilosella officinarum: Synchytrium aureum

14b Leaf blade with small downward outgrowths. In case of heavy infestation both halves bent upward along the midrib. Hieracium racemosum; Pilosella officinarum, onegensis, piloselloides subsp. praealta: Trioza proxima

14c Similar malformations. Hieracium sp.: Craspedolepta flavipennis

15a Yellowish-green to intensively reddened pustules, many per leaf, occasionally coalescing, especially frequent on basal leaves on the underside between epidermis and parenchyma. Larvae reddish-yellow to dark orange-red, up to 2 mm long. Hieracium and Pilosella: Cystiphora sanguinea

15b Initially yellowish-white, later brown (never reddish) rotund, sometimes weakly swollen irregularly margined spots. Hieracium and Pilosella: Entyloma hieracii

16a Loose roll of the leaf margin or curls of the leaf blade => 19

16b Narrow leaf roll, often simultaneously developing with swellings, or only ± expanded erinea, of the leaf blade => 17

17a Expanded, compact upward rolling of the leaf margin => 18

17b Short, densely felt-like pubescent marginal bulge or –nodule, corresponding nodules also on the leaf blade; sometimes strong erinea on the upper side, also on the underside venation. Hieracium lachenalii, murorum: Eriophyes villificus

18a Only known from Pilosella officinarum: Aceria pilosellae

18b As well on Hieracium as Pilosella: Aceria longiseta

19a Malformation predominantly a marginal rolling of the leaf blade => 21

19b Malformation predominantly as a markedly curved, additionally curled leaf, or as a slight bulging of the same organ => 20

20a The shoot is stunted on one side and slightly thickened; in the affected area leaves are clustered, the leaf blades curved, variously twisted and curled, locally coloured intense green. Hieracium and Pilosella: Philaenus spumarius

20b Weak, merely facultative, not discoloured swellings of the leaf blade. Aphid straw yellow, green or reddish; apterous adults dorsally with dark spots. Hieracium and Pilosella: Nasonovia ribisnigri

21a Leaf margins rolled upwards => 22

21b Leaves rolled downwards or often curved and ± strongly curled. Usually several leaves on the shoot tip are conspicuously malformed. Hieracium spp.: Aphis hieracii

22a In spring on the upperside of the leaves which fold upwards to enclose the colonies, later feeding on stems and inflorescences. Hieracium and Pilosella: Nasonovia compositellae

22b In spring inside upwardly rolled leaves, later moving onto stems and flowers. Hieracium alpinum, lachenalii, murorum; Pilosella aurantiaca, officinarum, piloselloides: Nasonovia pilosellae

23a Receptacle of one- or several capitula deformed => 24

23b Stalks of complete inflorescences shortened, thickened and curved. In the axils of clustered leaves 2–3 pale orange-yellow larvae. The development of neighbouring capitula often markedly stunted. Hieracium umbellatum: Unidentified gall midge

24a Inducers develop in the receptacle => 27

24b Inducers develop between the involucral scales => 25

25a Malformations caused by gall midges => 26

25b Malformations caused by gall mites. Capitula ± semiglobular, flowers markedly stunted and greened, flowers occasionally variously developing further. Hieracium and Pilosella: Aceria longiseta

26a Capitula often extensively shortened, usually enlarged on all sides. Several yellow, jumping larvae. Hieracium lachenalii, prenanthoides, umbellatum; Pilosella caespitosa, flagellaris, officinarum; Tolpis staticifolia: Contarinia pilosellae

26b Similar malformations of capitula on Hieracium murorum; Pilosella officinarum caused by orange-red, non-jumping midge larvae: Jaapiella compositarum

27a Conspicuous larvae developing solitarily or gregariously in distinct cavities of the receptacle => 28

27b The turgid, usually unilaterally malformed receptacle consists of a spongy, uniform parenchyma containing many eelworms. Pilosella cymosa, officinarum: Ditylenchus dipsaci

28a Whitish or yellowish maggots, , lacking a distinct head capsule => 29

28b Larvae with thoracic legs and distinct head capsule occurring in clearly swollen capitula. Hieracium amplexicaule, lachenalii, murorum, prenanthoides, umbellatum: Hellinsia didactylites

29a Malformations caused by tephritid larvae with conspicuous mouthparts and eventually developing a puparium => 30

29b Malformations caused by cynipid larvae, white. Hieracium lachenali: Aulacidea nibletti

30a Flower heads distinctly swollen at base, not opening, not conspicuously hardened; clearly curved if infected on one side; usually all capitula of a panicle infected. On many Hieracium and Pilosella species. Noeeta pupillata

30b Larvae in hardly disfigured flower heads. Pilosella lactucella, officinarum: Tephritis ruralis

30c Ditto. Hieracium murorum, sabaudum: Trupanea stellata

gallers on Elymus

pub 29.xi.2019

Dichotomous table for gallers on Elymus

(incl. Agropyron, Elytrigia, Hordelymus, Leymus, Roegneria, Sitanion, Thinopyrum)

by Hans Roskam

1a On shoots or shoot axis => 2

1b Roots with small slender, crooked or screw-like bent swellings. Elytrigia repens: Subanguina radicicola

= Furthermore, there are records of the cereal root-knot eelworm Meloidogyne naasi

2a On inflorescences or other generative parts => 27

2b On vegetative parts => 3

3a Malformations on culms or leaves caused by smuts => 25

3b Malformations caused by other fungi or by animals => 4

4a Malformations by animals => 6

4b Malformations by fungi => 5

5a Plants with systemic infections, growing rigidly erect, sterile; internodes shortened. Early infected leaves thickened irregularly, ± curved and disfigured; if infected later on the leaf blades are clearly widened; diseased leaf blades often with pale yellow stripes. Elytrigia repens: Physoderma graminis

5b Diseased leaves rolled and twisted, usually thickened conspicuously, pale, later brown and breaking up, exposing chestnut brown, globular naked oospores, 26–33 µm across. Spikes usually stunted, with disfigured, ± succulent, partially blue-green spikelets. Elymus caninus: Sclerospora graminicola

6a Malformation on shoot tips, and terminal shoots or on undeveloped shoots => 19

6b Malformations of culms, leaf sheaths or leaf blades => 7

7a Culm variously disfigured => 14

7b Malformations of leaves => 8

8a On leaf blades => 10

8b On leaf sheaths => 9

9a Leaf sheaths swollen, inhabited by aphids. Elytrigia repens: Laingia psammae

= Grain aphid, Sitobion avenae and/ or Blackberry cereal aphid, S. fragariae, known from many grasses, especially in inflorescences, cause also similar malformations on couch grass.

9b Leaf sheaths thickened above the nodes, usually open on one side. Several spindle-shaped galls inside. Larvae yellow. Elymus s.l.: Tetramesa hordei

10a Malformations of leaf blades caused by aphids => 12

10b Malformations of leaf blades caused by other parasites => 11

11a Leaf blade usually at base with tough, narrow, bulging, usually dark red coloured swellings. Elytrigia repens: Unidentified eelworm

11b Leaves remain unfolded or do not develop completely; discoloured. Elytrigia repens: Abacarus hystrix

= DNA-analysis has demonstrated that “A. hystrix” actually is a complex of a number of species.

12a Leaves rolled inwards by green aphids => 13

12b Leaves ± rolled upwards, often withering early. Aphid about 2 mm long, elongate, narrow, brownish-yellow with pale median stripe. Elytrigia repens: Sipha elegans

13a Leaves rolled upwards, twisted. Aphid 2–2.75 mm long, olive-green, reddish-brown between siphunculi. Elytrigia repens, Elymus caninus: Rhopalosiphum padi

13b Shoot stunted, leaves shortened, tuft-like accumulations. Leaf blades rolled, ± twisted. Agropyron cristatum; Elymus caninus; Elytrigia intermedia, repens: Diuraphis frequens

14a Culm swollen locally, galls contain larvae => 18

14b Inducers are outside galls => 15

15a Larvae in depressions on culm => 17

15b Causers not in distinct depressions => 16

16a Small, blister-shaped protuberances in long brown stripes or as crust-like cover. Elytrigia repens, Elymus caninus: Steneotarsonemus canestrinii

= Steneotarsonemus culmicolus occurs sometimes in the leaf sheaths of couch grass and other grasses and causes facultatively discoloured white spikes. Similar symptoms are also caused by Siteroptes cerealium, occurring on many grasses.

16b Shoot severely stunted. Inflorescence often remains largely hidden in the sheath. Culm at the base of the inflorescence ± swollen. Contains a single larva. Elytrigia repens: Oscinella frit and/ or the closely related O. pusilla

= Oscinella agropyri develops on couch grass without causing malformations.

17a Culm below leaf sheath usually above the upper node and the penultimate node with an expanded weak, usually blackened depression, containing a single orange-yellow to brick-red larva. Elytrigia repens, Elymus caninus: Hybolasioptera fasciata

17b Culm predominantly above the upper and penultimate nodes below the slightly swollen leaf sheath usually with oblong, saddle-shaped depressions, strongly inflated at the ends. Containing single 3–5 mm long bright red larvae. Elytrygia intermedia subsp. trichophora, repens: Haplodiplosis marginata

17c Recorded as inducer of further unspecified slight swelling of stems of Elytrigia repens: Lasioptera calamagrostidis

18a Culm at various places, often above a node or also close to the ground, with spindle-shaped, tough-walled, later on often yellowish-brown galls up to 7 mm long. Occasionally many per plant and fused in variable numbers and in various shapes, forming larger galls bulging from the sheaths as erupting swellings. Each chamber contains a yellow larva. Elymus s.l.: Tetramesa hordei

18b Culm below the often atrophied spikes which remain largely hidden in the sheaths often with several, ± fused, broad spindle-shaped to elongate-oval, very hard swellings, occasionally erupting from the sheaths. Each chamber contains a single larva. Elymus s.l.: Tetramesa hordei

18c Inside a culm or a hardened leaf sheath several ± oval, size of grain of rice size, galls. Culm at outside with irregular swellings, leaf sheath strongly swollen and ripped open. Containing a single pupa or white larva. Elytrigia repens, juncea: Tetramesa linearis

19a Shoot severely stunted already early in development, inflorescence usually not developing => 22

19b Terminal malformation on developed shoots => 20

20a Galls caused by chalcidoid larvae, with tuft of 3 or 4 conspicuously enlarged, increasingly shortened unfolding leaf blades => 21

20b Tip of shoot markedly shortened, swollen. Leaves clustered tuft-like, their sheaths shortened and broadened. The ± reduced leaf blades are usually not broadened and are appressed with their bases against the gall. Gall containing a single maggot. Elymus caninus; Elytrigia atherica, juncea, repens: Chlorops pumilionis

= Chlorops strigulus, C. interruptus, C. marchali and C. speciosus are all non-cecidogenous parasites of Elytrigia repens. – Concerning affiliation of the inducer of malformations on couch grass examination of larvae and rearing of adults is necessary.

21a Malformations, usually distinguished from fly galls by larger size length and width. Larval chamber in pith, oblong, thick-walled, usually extending over 3–4 internodes. Elymus caninus; Elytrigia intermedia, repens: Tetramesa hyalipennis

21b Similar, usually broader galls, up to 40 mm long, on Elytrigia juncea: Tetramesa maritima

22a Leaf blades mostly developed, but plants remain sterile => 23

22b Shoot tips etiolated, elongated, bent, spindle-shaped, enlarged. Elytrigia repens: ? Dasiops latifrons

23a Malformations caused by maggots => 24

23b Young shoots severely stunted; close to the ground ± conspicuously sponge-like swollen to large extent. Leaf blades shortened and disfigured to a varied extent. Elymus s.l.: Ditylenchus dipsaci

23c Short, compact onion-like galls arising from the basal part of young shoots, containing many eelworms: Elymus s.l.: Anguina agropyri

24a Young shoots sometimes, if many larvae or puparia present, slightly swollen. Leaves initially more erect, darker green and more compact than those of healthy plants. Central leaves often withering later on or dying; shoots with sessile, etiolated spikes; culms sometimes slightly swollen and often cracked above the basal nodes. Contain several white larvae and flax seeds-like puparia. Elytrigia repens, etc.: Mayetiola destructor

= Larvae, whitish ± 3 mm long, or puparia of Mayetiola baudysi live within a leaf sheath just above a node, causing a light, often brownish swelling on Elytrigia repens

24b Infected rudiments of shoots severely stunted, sometimes slightly swollen at base. Central leaves soon yellowing and withering. Shoots occasionally developing additional tillers. Elymus s.l.: Delia coarctata

25a Narrow stripes on leaf blades and -sheaths caused by smuts, rarely on culms => 26

25b Patches with smut predominantly on sterile remaining culms which initially grow faster. A number of internodes often noticeably enlarged. Elymus s.l.: Tranzscheliella hypodytes

26a Plants often severely stunted. Stripes long, narrow, ± coalescing, almost black; lacerating the leaf blade if ripped open. Spores slightly dusty, separated, spherical to rotund-oval, about 11–18 µm across. Membrane with blunt, sometimes coalescing warts. Elytrigia repens, more rarely on Elytrigia juncea, Elymus caninus: Ustilago serpens

26b Infected stems at first developing quickly, later on stunted, often remaining sterile, extensively covered with brown-black patches with spores. Elymus caninus, Elytrigia juncea, repens: Tranzscheliella hypodytes

26c Similar infestation. Spores blackish, solitary or aggregated in pairs, however, more rarely with 3–4 together and enveloped by several accessory cells which have a pale yellow membrane. Elymus s.l.: Urocystis agropyri

26d Ditto on Elytrigia atherica, campestris, pungens: Urocystis agropyri-campestris

27a Malformations caused by parasitic fungi => 29

27b Malformations caused by animals => 28

28a Inflorescence usually disfigured over extensive patches. Spikelets according to degree of infestation ± disfigured and greened or discoloured, stunted. Elytrigia repens, Leymus arenarius: Aceria tenuis

= Occasionally this mite is associated with Aceria cornuta.

= Proliferations of flowers of Elytrigia repens are teratological malformations.

28b Flowers greened. Elymus caninus: Inducer not clarified – ? Eelworm

29a Patches with smuts extending to other flowering parts. Elymus caninus, trachycaulus: Ustilago bullata

29b Patches with smuts restricted to ovaries. Smut grains foul-smelling, oblong, grey- to blackish brown, enclosed by slightly spreading glumes. Spores globular, 18–22 µm across; membrane reticulate. Elymus s.l.: Tilletia controversa

= Conspicuously protruding, rough, often bent bodies, black on outside and white on inside, are not true galls, but are sclerotia of ergot Claviceps purpurea, frequent on couch grass. The identity of ergot on Elytrigia juncea has not been clarified

gallers on Crepis

pub 28.xi.2019

Dichotomous table for gallers on Crepis

(incl. Aetheorhiza)

by Hans Roskam

1a On above-ground parts => 2

1b Roots with nodule- to spindle-shaped swellings. Crepis spp.: Meloidogyne hapla

1c Rounded root galls 4–5 mm long on Aetheorhiza bulbosa: Entyloma crepidicola

2a Malformations of capitula => 28

2b Galls on vegetative parts => 3

3a Malformations with fruiting bodies of fungi on the outside => 21

3b Malformations caused by animals or by fungi whose fruiting bodies develop inside the galls => 4

4a Galls exclusively or predominantly on the stems => 18

4b Galls only or mainly on leaves => 5

5a Galls especially on midrib and main veins, only secondarily on leaf blades => 13

5b Galls largely extended over the leaf blades-, or local, induced by psyllids, gall midges or gall mites and fungi => 6

6a Malformations of undefined shape, extending over the whole leaf blade => 12

6b Galls of ± defined shape and size => 7

7a Malformations with abnormal pubescence => 11

7b Galls glabrous or without supplementary pubescence => 8

8a Galls only about 1–3 mm long, wart- or callus-shaped => 9

8b Leaf blade usually with several rotund, up to 4 mm wide, pale green, often yellowish or reddish bordered pock-shaped upward bulges. Galls only closed by the epidermis beneath, a red-yellow larva showing through. C. biennis, conyzifolia, praemorsa, Aetheorhiza bulbosa, etc.: Cystiphora sp.

9a Galls pearl-like, often very many on the underside, sometimes also on upper side of the rosette leaves, hardly 1 mm long, red- to golden yellow translucent. Occasionally also occurring on leaf veins and petioles and below on the stem; sometimes forming crusts or bars resulting in further malformation of the plant parts => 10

9b Leaves with rotund, 1–3 mm wide, slightly protruding yellow-grey bulges. C. biennis, rubra: Entyloma crepidis-rubrae

10a On C. biennis. Leaf blades with pearl-like, compound galls, often aggregating into extended, orange-yellow, or blood-red crusts: Synchytrium taraxaci

10b On C. alpestris, biennis. Orange- to golden yellow multicellular warts: Synchytrium aureum

11a Protrusions of the leaf underside with erineum. C. paludosa: Unidentified gall mite

11b Similar malformation, in connection with narrow, abnormal pubescent marginal rolling, usually only short upwards stripe. C. praemorsa: Unidentified gall mite

12a Leaf blades of basal leaves sometimes with several dimple-shaped depressions on the underside, each dimple with one larva. Leaf blades, which are occupied by many older larvae, are deformed and have deflected, often ± twisted, margins. C. biennis: Craspedolepta flavipennis

12b Malformation of the leaf blades by aphids: Nasonovia ribisnigri

12c Leaf blade apex and margins nest-like downwardly curved, especially close to the site of attack strongly curled and dark green. Infestation of stem is accompanied by localised stunting and curving of the stem, which bears 2–3 closely situated bent and curled leaves. C. biennis, pyrenaica, paludosa: Philaenus spumarius

13a Extensive galls on the midrib, often already emerging from leaf base => 16

13b Galls on other sites, not connected with the leaf base => 14

14a Nodule- or bulge-like, massive galls on the veins, without a central chamber, the inside with fungus spores => 15

14b Midrib with pale spindle-shaped swelling; one larva inside. C. biennis: Unidentified gall midge

15a Galls predominantly on leaf tips. Infected parts initially yellowish, brown-red later on; often bladder-like swelling on upper side; veins also swollen, especially protruding on underside, often conspicuously reddened. Spores in vascular tissue. C. biennis: Protomyces crepidicola

15b Nodule-like, chocolate-brown swellings on the main- and midribs of the leaves, as well as more bulged swellings of the basal stem parts. Spores in and next to the vascular bundles. C. paludosa: Protomyces crepidis-paludosae

15c Leaf galls on C. froehlichiana subsp. dinarica. Bulges about 0.5–0.75 mm wide, ± grey-yellow, protruding hemispherically on the underside, often many per leaf blade: Protomycopsis crepidis

16a Midrib at its base up to three times its normal size, swollen. Gall gradually narrowed to mid-leaf, or further, swelling not extending to the sometimes nested leaf blade parts. Contains a maggot inside => 17

16b Midrib of several, often severely stunted rosette leaves, including adjacent leaf blade parts usually spongy, swollen, pale green, sometimes, ± reddened. Many eelworms inside. C. biennis, capillaris, paludosa, tectorum: Ditylenchus dipsaci

17a Rosette leaves, more rarely stem leaves, mined. C. biennis: Phytomyza robustella

17b Similar galls, mainly in basal leaves of C. paludosa: Phytomyza araciocecis

18a Galls glabrous, tough-walled. Contain larvae => 19

18b Galls spongy, pale green, with ± rugose surface. Very differently extending, even many cm long. Stem swollen on all sides, or more one-sided; internodes often strongly shortened, spirally twisted, curled or bent. Infestation especially on the basal leaf parts; occasionally also to a different degree in the swollen, ± nodding and closed capitula. C. biennis, capillaris, foetida subsp. rhoeadifolia, taraxacifolia, etc.: Ditylenchus dipsaci

19a wellings close to the stem base => 20

19b Stem with ± spindle-shaped swellings, about 10–40 mm long and 6–15 mm broad, sometimes multiple hunchbacked, also bent. Galls on main stems of C. biennis often united to 15 and more cm long, ± large chambered swellings. Inside the greatly enlarged pith are many, lateral- or central compact-shelled larval chambers. One larva per chamber. C. biennis, capillaris, tectorum: Aulacidea sp.

19c Similar galls are also described from C. paludosa, taraxifolia: Phanacis lusitanica

19d Corresponding galls on C. pulchra: Phanacis rufipes

20a Stem bases of young plants stunted, swollen to a different extent, with ± reduced and mutually close leaves. In the swollen pith is a boring maggot. C. capillaris: Napomyza lateralis

20b Basal part of stem, including root collar severely shortened and swollen; occasionally bent, partially bushy (phyllanthy). Several white larvae inside. C. setosa: Unidentified beetle

21a Malformations with spores of rust fungi => 23

21b Malformations caused by other fungi => 22

22a Internodes shortened, plant very bushy; development of flowers stunted in strong infestations; stem and leaves irregularly curved, with small spore-bearing pock-like depressions. C. biennis, capillaris: Didymaria matricariae

22b Leaf blade initially with dark green, later on yellowish, ± vesicular swellings, showing grey-white layers of asci after ripening. C. conyzifolia, mollis, pygmaea, pyrenaica: Volkartia rhaetica

23a Fungus host alternating, on Crepis only producing aecia and pycnidia. Sori sometimes slightly blistered, swollen => 27

23b Fungus host-specific, all spore types developing on Crepis; gall-like malformations only by the aecidial stage with thickened inner wall of the peridium => 24

24a Aecia-producing mycelium locally, sori facultatively blistered, swollen => 26

24b Aecia-producing mycelium extending over large areas within the usually sterile host; cups scattered, usually occurring on all leaves of the host => 25

25a Whole plant changed. Diseased leaves upright, often narrowed, thickened, abnormally pale; on the underside and partially also upperside, with many aecia and pycnidia. Infected stem ± swollen, initially taller than the healthy ones, pale green, often remaining sterile. C. capillaris, tectorum, etc.: Puccinia crepidis

25b Pycnia and aecia on C. aurea: Uredo breventiaca

25c Pycnia and aecia on C. foetida incl. subsp. rhoeadifolia: Puccinia barkhausiae-rhoeadifoliae

26a The closely situated aecia in yellowish, sometimes red margined bulge-like swellings. These are rotund on the leaf underside and oblong on the veins and stems. Intensity of gall formation depends upon interaction of host and parasite. Basic differences between the malformations caused by the following species are absent. Wall cells of the pseudo-peridium in irregular rows, the inside thickened. Uredinia and telia not cecidogenic, in small sori, widely distributed on leaves and stem. Fungi differ in microscopic characters, especially if telia are present and largely according to the host. Stages with pycnia and aecia are facultatively cecidogenic:

a On C. biennis: Puccinia praecox

b On C. paludosa: Puccinia major

c On C. alpestris: Puccinia alpestris

d On C. aurea: Puccinia crepidis-aureae

e On C. pyrenaica, also on alpestris, capillaris, tectorum: Puccinia crepidis-blattarioidis

f On C. conyzifolia: Puccinia crepidis-grandiflorae

g On C. foetida, taraxifolia, etc.: Puccinia crepidicola

h On C. jacquini: Puccinia krupae

i On C. mollis: Puccinia crucheti

j On C. [Intybus] praemorsa: Puccinia intybi

k On C. pygmaea: Puccinia crepidis-pygmaeae

l On C. sibirica: Puccinia crepidis-sibiricae

27a Sori often bright yellow, sometimes red margined, not- or only slightly thickened. Usually freely situated on the leaf blade, rotund, on the underside slightly bulging, on the upper side slightly depressed and occupied with spots of brownish pycnidia; the aecia on the underside with well-developed pseudoperidia, which open cup-shaped, their cells in regular rows and thickened on the outside. C. biennis, more rarely C. capillaris, taraxacifolia, vesicaria: Puccinia opizii

27b Cushions on the leaf blade more distinctly bulged; pycnia and aecia mainly on the venation, possibly on petioles and even on stems. C. biennis: Puccinia silvatica

28a Capitula greened and leafy, with a multiplication of flower peduncles supporting small malformed capitula (phyllanthy => 31

28b Capitula stunted, weakly thickened, remaining closed => 29

29a Malformations by gall midge larvae => 30

29b Malformations by fly maggots. C. biennis: Noeeta crepidis

29c Capitula swollen, peduncles swollen just below the flower head; stems also swollen if attacked in rare cases. C. taraxacifolia: Ditylenchus dipsaci

30a Several yellow, jumping larvae occur in the basally weakly thickened and twisted capitula. C. biennis, etc.: Contarinia hypochoeridis

30b Malformed capitula with pale, non-jumping larvae. C. paludosa: Unidentified gall midge

31a Capitula, often in large numbers per plant, completely deformed, sometimes partially developing into further, similarly deformed reduced capitula. Involucre often not changed, corollas severely stunted and ± greened; anthers and ovaries changed into green, ± leafy structures. C. biennis, capillaris, tectorum: Aceria rechingeri

= The gall mite Phyllocoptes oligostictus is inquiline in enlarged flower heads of C. biennis caused by Aceria rechingeri

31b Capitula almost witches’ broom-like, sometimes even repeatedly developing into stalked smaller capitula; flowers often hardly, sometimes unrecognisably deformed though with ± lanceolate, leafy structures instead. Usually all capitula of a host are similarly deformed. C. biennis, tectorum: Inducer unknown

gallers on Chrysanthemum

pub 26.xi.2019

Dichotomous table for gallers on Chrysanthemum

(incl. Argyranthemum, Coleostephus, Dendranthema, Leucanthemum, Leucanthemopsis, Parthenium, Pyrethrum, Tanacetum pp.)

by Hans Roskam

1a On above-ground upper plant parts => 6

1b On roots, rhizomes or root collars => 2

2a On root collar, rhizome or subterranean buds => 3

2b Roots with small nodule-shaped swellings. Chrysanthemum spp.: Meloidogyne hapla

3a Considerable proliferations on the root collar => 5

3b On rhizome buds or rhizomes => 4

4a Rhizomes with rotund swellings, up to 5 mm long, succulent, containing one or several chambers. A white larva develops in each chamber. Leucanthemum vulgare, Tanacetum corymbosum: Oxyna nebulosa

4b Stem of the upper root part, especially the basal buds, thickened; rosette stunted; leaves swollen to a uniform fleshy gall, remaining closed; ± covered by stunted leaf parts. Larva reddish. Leucanthemum atratum, L. vulgare: Rhopalomyia hypogaea

5a Crop-like proliferations, globular, usually uniformly, with compact rough surface. Chrysanthemum spp.: Agrobacterium tumefaciens

5b Ramification of root collar. Shoots only stub-shaped, irregular, partially even leaf-like broadened, fleshy thickened; forming ± dense witches’ broom-like clusters composed of markedly degenerate leaves. Chrysanthemum spp.: Rhodococcus fascians

6a Galls on capitula, flowers or fruits => 28

6b Malformations of vegetative plant parts, occasionally also protruding parts of, or complete inflorescences => 7

7a Malformations exclusively, or predominantly, on leaves or apical shoots => 12

7b Malformations mainly on stems, sometimes additionally also on the petioles and leaf veins => 8

8a The inducers are inside the galls => 9

8b Stem over various lengths ± bulged, swollen, occasionally curled. On the rind some to many, wall-like framed depressions containing a flat scale insect. Leucanthemum vulgare: Planchonia arabidis

9a Malformations ± expanded, however with locally distinct solitary galls => 11

9b Malformations of different dimensions, without distinct solitary galls => 10

10a Stem slightly swollen close to the inflorescence, somewhat stunted and more pubescent. In the hollowed pith is a caterpillar, which often also ± infests the receptacle. Leucanthemum vulgare: Unidentified lepidopteran

10b Stem mainly underneath the flower head differently malformed, often over extended length, spongy, swollen, partially screw-like curled or curved. Neighbouring capitula stunted and deformed to a different extent. Leucanthemum: Ditylenchus dipsaci

11a Stem internodes ± stunted and swollen, occupied often with many, 2–3 mm long, acute-conical, ± obliquely protruding, ± pubescent galls. Corresponding galls often simultaneously also on leaves and sometimes axillary buds and even galling parts of the inflorescence. Hosts in case of severe infestation often largely deformed. Larvae initially milk-white, yellowish to red-orange later on. C. indicum, rubellum, incl. various forms: Rhopalomyia chrysanthemi

11b Similar malformations of stem and buds with usually less many fleshy galls. One reddish larva per gall chamber. Leucanthemum vulgare etc.: Rhopalomyia hypogaea

12a Wart-shaped, distinctly defined swelling caused by fungi, hardly 1 mm long or ± flat callous, which fruit either in the inside or on the surface of the galls => 24

12b Leaves with strongly protruding swellings, flat, ± irregularly bordered or with expanded marginal rolls and curls, usually caused by animals => 13

13a Leaf blades with malformations of various shape and growth, usually on several terminal leaves; caused by aphids, cercopids, leaf-hoppers or erineum-like fruiting fungi => 20

13b Leaves with locally restricted malformations, often many or with narrow rolls => 14

14a Conspicuous malformations of the leaf margin => 18

14b Malformations of the leaf blade => 15

15a Leaf blade with succulent, conical, or nodule- to bulge-like galls => 16

15b Leaf blades predominantly of the rosette leaves, with many dimple-shaped swellings, protruding on the upper side. Leucanthemum vulgare: Trioza chrysanthemi

15c Similar dimples on the basal leaves containing froth-covered nymphs. Leucanthemum vulgare: Craspedolepta flavipennis

15d Slightly locally suberose leaf swellings. Thrips nigropilosus

16a Galls up to 3 mm long, conical or nodule-shaped => 17

16b Petioles, usually of several rosette leaves, shortened, markedly spongy, swollen, pale green. Swellings variously extending into the leaf blade; sometimes ± isolated on the leaf blade and fading from a rugose vein into the leaf blade, again conspicuously pale green. Leucanthemum maximum: Ditylenchus dipsaci

17a Leaf blade with nodular swellings, Tanacetum corymbosum: Unidentified eelworm

17b Leaves often with many conical galls, on the upper side or also beneath, obliquely protruding, 2–2.5 mm long. Corresponding lumps often simultaneously on other plant parts. Larvae initially milk white, later red-orange. C. indicum: Rhopalomyia chrysanthemi

18a Leaf blade margin lacerate => 19

18b Leaves with downward rolls. Tanacetum corymbosum: Unidentified psyllid

19a Leaf blade lacerate, with small protrusions on the upper side. Leucanthemum vulgare: Unidentified gall mite

19b Leaf blade deeply and irregularly striped, long white pubescent. Tanacetum corymbosum: Cause unknown – ? gall mite

20a Leaf blade bent and curled by animal parasites => 21

20b Leaves usually with several shoot tips locally or completely bleached, swollen, ± curved or deformed in other ways; the underside soon covered by a coherent dirty violet fungus. Capitula, if present, severely stunted, sometimes with hardly spreading, shortened and greened ligules and likewise ± greened tubular florets. C. segetum: Peronospora danica

21a Malformations by aphids => 22

21b Leaves nest-like contracted, close to the site of attack curled, dark green. Infestation of stem leaves or stems often leads to curved, one-sided thickened stems with converged, ± rolled leaves. Infestation of stem parts close to the capitula results in diverse malformations on inflorescences and flowers. Chrysanthemum spp.: Philaenus spumarius

22a On Leucanthemum vulgare, Tanacetum corymbosum => 23

22b On Chrysanthemum indicum, Argyranthemum frutescens. Leaves and also flower parts deflected. Aphids dark browns to black. 1.5–2.5 mm long, antennae as long as body, siphunculi thick, conical, slightly shorter than the long cauda: Macrosiphoniella sanborni

22c Superior internodes strongly shortened, with dense tufts of leaves and stunted capitula. Argyranthemum frutescens: Macrosiphoniella artemisiae

= Various malformations of shoot- and inflorescences may be virus-associated.

23a Leaf blade of Leucanthemum vulgare deformed by green aphids, curved. Attack on terminal shoots results in considerable stunting and curling of plant parts, incl. capitula and flowers. Aphid about 2–2.3 mm long and with almost black siphunculi: Brachycaudus cardui

23b In similar malformations on several Chrysanthemum species occurs another aphid, which is only 1.5–2 mm long with green to olive-brown siphunculi: Brachycaudus helichrysi

23c Basal leaves of Tanacetum corymbosum curved, soon yellowing: Macrosiphoniella miestingeri

24a Sori cushion- or bulge-shaped; fruiting bodies at the surface, on Leucanthemum vulgare => 27

24b Galls wart- or pock-like with spores inside => 25

25a Galls nodule-shaped, over 1 mm wide => 26

25b Underside of the rosette leaves often with many, hardly 1 mm long hemispherical, pearl-like warts, with a yellowish translucent fungal body. in the middle. Leucanthemum vulgare: Synchytrium aureum

26a Usually distinct, rotund, flat pocks up to about 2 mm long, initially grey-white, later browned, predominantly solitary; mostly with several on the underside of basal- as well as stem leaves; more rarely on petioles or stems. Spores of various size, thick-walled; terminally produced on the mycelium ramifications, outside the vascular bundle. Leucanthemum vulgare: Protomycopsis leucanthemi

26b Similar, mostly less conspicuous flat, initially whitish-yellow pocks on the leaf underside, sometimes also on the stems of the inflorescences. Leucanthemopsis alpina: Protomycopsis leucanthemi

27a Underside of the rosette leaves mostly with many, small, rotund, brown telia; if produced on petioles of young leaves in especially early spring sometimes slightly swollen, mostly yellow-margined, oblong-oval cushions. No host alternation: Puccinia leucanthemi

27b Leaf underside with rotund, 3–10 mm wide yellowish, often purple-margined aecia. Sori on main veins sometimes slightly bulge-like swellings. Species alternating on Carex montana: Puccinia aecidii-leucanthemi

27c Similar aecia, on the same host but alternating on Carex caryophyllea, ericetorum: Puccinia leucanthemi-vernae

28a Galls mainly locally in capitula, on the receptacle, involucre, bracts or fruits => 35

28b Malformations over ± extensive parts of the inflorescence => 29

28c Slight swelling of main stem below flower head, causing distortion of head, with side shoots growing past it; larva tunnels inside stem and often into flower head from which frass may exude, in stem or head (or in ground). Leucanthemum vulgare: Dichrorampha consortana

29a Malformations of approximately well-defined shape, involving the receptacle => 33

29b Malformations of varying extensions on parts or complete capitula => 30

30a Malformations of ± open capitula => 32

30b Capitula stunted, remaining closed => 31

31a Capitula slightly swollen; several yellow to pink jumping larvae between the achenes. Leucanthemum vulgare, maximum: Contarinia chrysanthemi

= The gall midge Dasineura chrysanthemi has been recorded from flower heads of Leucanthemum vulgare; as well midge larvae assigned to Jaapiella sp.

31b Complete flower head deformed, flowers aborted. Leucanthemum vulgare: Paraphytoptus chrysanthemi

= For the ornamentally cultivated C. carinatum, indicum, conspicuous damage caused by viruses has been recorded. Malformations consisting of greening of the flowers in connection with malformations of the capitula

32a Malformations caused by aphids or cercopids => 21

32b Inflorescence variously stunted or deformed; infected organs partially covered with an area of loosely, dichotomous, grey-violet conidiophores. Tubuliform flowers often soon withered, infected ligules elongated, often variously curved, usually with abundant oospores, lacking conidiophores. Leucanthemum vulgare: Peronospora radii

33a Receptacle swollen, without involvement of the often strongly atrophied flowers => 34

33b Receptacle locally, including one or several flowers, initially swollen to a succulent, conical, apically almost closed gall, surmounting the later ± deformed disc. One reddish larva. Leucanthemum vulgare: Rhopalomyia hypogaea

= Similar galls but with terminally spreading lobes later on Leucanthemum vulgare are caused by the gall midge Rhopalomyia tanaceticola which lives usually on Tanacetum.

34a Receptacle deformed, ± swollen, hardened. Leucanthemum vulgare: cf. Eurasimona stigma

= According to Smit (2010) the capitula of Leucanthemum vulgare are also infested by the tephritid fly Tephritis neesii; widely distributed in Eu, no records from E-Eu.

34b Receptacle almost only enlarged in combination with corresponding swellings on the neighbouring parts of the stem and accordingly curved. Leucanthemum vulgare, maximum: Ditylenchus dipsaci

35a Up to 2 mm long, obliquely protruding, conical galls on leaves of the involucre and solitarily scattered even on the ligules. C. indicum: Rhopalomyia chrysanthemi

35b Ovary or fruit swollen without or together with the lower flower parts. Also the bract may be involved in the gall formation. One yellow larva. Chrysanthemum argenteum (Tripleurospermum inodorum and Anthemis bornmuelleri are main hosts; furthermore Leucanthemum vulgare: Ozirhincus longicollis

35c Similar galls; Chrysanthemum coronarium, segetum: Ozirhincus anthemidis

= O. longicollis and O. anthemidis differ by the length of the adult proboscis: in O. longicollis proboscis long, from base of labrum to tip of labella longer than height of eye; in O. anthemidis proboscis shorter than height of eye.

gallers on Alnus

pub 26.xi.2019

Dichotomous table for gallers on Alnus

by Hans Roskam

1a On parts above ground => 2

1b Lateral roots initially with small, nodule-like, later on with rotund, hazelnut- to fist-size gall masses (rhizothamnia), composed of thick, coral-like branches, usually densely clustered. Alnus spp.: Frankia alni

1c The disease usually starts at the roots and root collar, and extends from there in a few years up into the crown; it manifests itself by large brown bleeding bark lesions, later in a reduction of the foliage and branch die-back. A. cordata, glutinosa, incana: Phytophthora alni

2a On shoots or leaves => 4

2b On flowers or inflorescences => 3

3a Cone scales broadly band-like proliferating, succulent, often temporarily ± reddened, eventually browned. Alnus spp.: Taphrina alni

3b Male catkins distorted, sometimes knobby or appearing thickened over their whole length. Containing a single larva. Alnus spp.: Unidentified lepidopteran

3c s occasional inhabitants of gall-like malformations the following species have been recorded: Epinotia immundana and/ or E. tenerana

4a On leaves => 11

4b On shoots => 5

5a Malformations witches’ broom-like or occupied by mistletoe => 10

5b Malformations different => 6

6a The inducers develop inside the malformations; or have their fruiting bodies on the surface => 7

6b The inducers are to be found in ± lenticular rimmed depressions, up to about 2 mm long, on the bark of young, already woody twigs. A. glutinosa, incana: Chionaspis salicis

= The “alder spittlebug” Aphrophora alni causes distinctive calloused rings on shoots

7a Localised malformations on young woody twigs with tunnels bored inside => 9

7b Malformations caused by fungi, which at least temporarily have their fruiting bodies developing on the surface => 8

8a Bark of older shoots with ± fissured, initially closed, later on centrally open, ridge-like bordered cancer wounds. “Nectria cancer”. A. incana: Neonectria major

= The polyphagous Agrobacterium tumefaciens is also reported from alder as inducer of closed cancers

8b Axial parts of young shoots conspicuously swollen usually over their whole length. Leaves often remarkably swollen, bladder-like and curled. A. glutinosa, glutinosa x incana, rubra (cult.): Taphrina tosquinetii

9a One year old shoots with swelling, up to 10 mm long and about 5 mm broad, downwardly gradually narrowed. The pith contains a yellowish or pale green caterpillar with brown-yellowish head and often a darker neck shield. Alnus spp.: Epinotia tetraquetrana

9b Elongated, weak, eventually usually dehiscing swelling in terminal part of twig. Contains a single larva. A. glutinosa, incana, viridis, etc.: Heliozela resplendella

= The larvae of the snout beetle Cryptorhynchus lapathi tunnel in older stems, as well as in many other woody hosts, which results in conspicuous deformations. However, these results of regeneration are not true galls.

10a Heavier stems with ± distinct spindle- or barrel-like swellings, from which sprout Viscum album

10b Loose to densely bushy, often conspicuous witches’ broom. Shoots elongated, rigidly erect, considerably thickened, especially at base, with many lenticels. Brooms 2–3 (–4) years overlaying, often many per tree. Leaves often slightly thickened, paler, more curled than healthy ones. A. glutinosa x incana, incana: Taphrina epiphylla

10c A fungus with similar symptoms has been described as Taphrina tosquinetii

11a Malformations only on petioles or main veins, not or only secondarily extending to the leaf blade, without accessory pubescence => 27

11b Malformations on leaf blades close to the major veins or including them => 12

12a Galls mostly on expanded, fully developed leaves => 15

12b Malformations on young leaves or leaf blades over the midrib ± folded upwards => 13

13a Leaf blade, according to the extent of development at infection time, ± completely upwardly folded. Midrib and basal parts of the side veins ± spongy, thickened. Gall midge larvae present between the folds => 14

13b Young leaves curled together. Veins undulate. A. glutinosa: Aceria longirostris

14a Larvae gregarious, initially white, later red. A. glutinosa, incana, glutinosa x incana; also on cultivated alders: Dasineura tortilis

14b In similar galls live gregarious yellow larvae with terminal red parts: Jaapiella clethrophila

= Furthermore reddish-yellow larvae of the gall midge Macrolabis alnicola, also an inquiline of D. tortilis

15a Malformations with conspicuous abnormal pubescence which is visible from the outside => 22

15b Pubescence of gall surface normal => 16

16a Leaf blades with ± expanded bladder-shaped swellings => 18

16b Galls globular, 1–2 mm across, constricted at base, often many on the upper side of the leaves, yellowish-green or sometimes reddened. Opening on underside, surrounded by a glabrous rim; only the inside pubescent => 17

17a On A. glutinosa: Eriophyes laevis

17b On A. incana: Eriophyes alniincanae

18a Galls caused by fungi, whose fruiting bodies develop at maturity as loose, ash-grey coverings of upwardly bent leaf undersides => 19

18b Leaf blade with flat, ± extended, not acutely delimited, initially pale, later on brownish swellings with many mites on the underside. Alnus spp.: Tegonotus heptacanthus

18c Similar malformations of mites which are known as inquilines in other mite galls on alder have occasionally been reported: Tegonotus trouessarti and/ or Acaricalus trinotus

19a Swellings only flat, ± pale green, slightly extended; usually with several present on the slightly enlarged leaf blades => 20

19b Leaf blade considerably enlarged, completely or the major part heavily bladder-like swollen, pale green. Alnus spp.: Taphrina tosquinetii

20a On A. incana, viridis => 21

20b On A. glutinosa, glutinosa x incana, incana and cultivated species: Taphrina sadebeckii

21a On A. viridis: Taphrina viridis

21b On A. incana: Taphrina epiphylla

22a Erinea not noticeably encroaching on the venation, or mostly restricted to the vein axils => 23

22b The often expanded areas with abnormal pubescence predominantly along the midrib and lateral veins, secondarily also on the leaf blade and petiole. Pubescence dense, hair longer than normal. Erinea initially white, brown later on. A. glutinosa, incana: Unidentified gall mite

23a Erinea distributed over the leaf blade without particular pattern => 24

23b Galls mostly in the vein axils along the midrib, often on both leaf halves; over a length of 2–3 mm, protruding upwards, initially yellowish, brownish later. In the cavity on the underside initially white, later on ± browned, hairs. On the central part of the erineum slim club-shaped hairs, with acuminate rigid hairs on the margin. Alnus spp.: Eriophyes inangulis

24a Hairs in erinea club-shaped or cylindrical, only slightly different from the normal ones => 25

24b Hairs on top distinctly broadened, irregular bumpy or lobed, head- or toadstool-shaped. Erinea on the underside, more rarely also on the upper side, forming initially yellowish-white, later on rust-brown, oval spots or more extensive coverings. Alnus spp.: Acalitus brevitarsus

25a Hairs cylindrical or slightly club-shaped, irregularly bent and intricate => 26

25b Hairs slightly different from normal ones. Erinea on the underside in weak archings of the leaf blade. A. glutinosa, incana: Unidentified gall mite

26a On A. glutinosa, incana, glutinosa x incana. Erinea on underside, more rarely upper side, mostly rotund-ovate, initially white, reddened later on: Acalitus phyllereus and/ or Aceria bistriata

26b On A. viridis. Erinea usually on upper side and peach red, later like the previous species: Eriophyes euryporus and/ or Aceria bistriata

= The eriophyoid mite Aceria alniviridis has been recorded as inquiline in galls of Eriophyes euryporus

27a The malformations result from oviposition and are already vacated by the departed larvae. “Procecidia”: oviposition scars, not true galls => 28

27b Petioles ± distinctly swollen and sometimes appearing shortened, usually bursting open later. Caterpillar often only occurring in the ± swollen petioles, eventually appearing with a short, full depth corridor into the leaf blade, cutting an oblong-ovate case, and dropping to the ground in that housing. Alnus spp.: Heliozela resplendella

28a Procecidia (oviposition scars) on petiole, sometimes extending to midrib => 30

28b Procecidia on the veins only => 29

29a Midrib with up to 8 punctures made on the leaf upper side; procecidia arranged longitudinally, contacting one another. Batches bursting downwards, recognizable for a longer time. Alnus spp.: Eriocampa ovata and/ or E. umbratica

29b Midrib on the leaf underside usually with up to 15 procecidia, inconspicuous and hardly permanent, which are arranged in one row. Alnus spp.: Craesus septentrionalis

30a Egg capsules usually on both-sides of petiole or in the midrib; now left, now right, alternating or opposite. Alnus spp.: Hemichroa crocea

30b Egg batches on petiole solitary. Alnus spp.: Hemichroa australis

gallers on Veronica

pub 24.xi.2019

Dichotomous table for gallers on Veronica

by Hans Roskam

(incl. Paederota bonarota, lutea; Pseudolysimachion longifolium, spicatum, spurium)

1a On parts above ground => 2

1b Roots with small nodular to spindle-shaped swellings. Veronica spp.: Meloidogyne hapla

2a On inflorescences, flowers or fruits => 36

2b On stems, shoot tips or leaves => 3

3a On stem parts below shoot tip => 9

3b On tips of main- and side shoots => 4

4a Galls irregular, tuft- or ball-like => 7

4b Galls almost regular, bud-like or pouch-shaped => 5

5a Terminal leaf pair folded upwards together, narrowed, thickened, especially basally discoloured or reddened. V. scutellata, serpyllifolia, anagallis-aquatica, beccabunga => 6

5b Terminal leaf pair folded together, pouch-like, swollen, thickened. Transformed into a uniform, usually broad conical, sometimes laterally flattened, 2-valved, 5–10 mm long gall. On glabrous Veronica species glabrous and inconspicuous, sometimes reddened basally; on pubescent hosts ± strongly to even white-woolly haired and often of conspicuous size. Containing orange-red larvae. Veronica spp.: Jaapiella veronicae

= Inquilines: Whitish-yellow midge larvae of Macrolabis incolens

6a On V. scutellata, etc. Terminal pair of leaves folded together in an erect, reddened, spindle-shaped gall. Containing several orange-red larvae: Dasineura similis

6b Similar, however much smaller, glabrous malformations on V. serpyllifolia: Jaapiella veronicae

7a Malformations caused by gall mites on clustered terminal vegetative, or generative parts => 8

7b Shoot tip stunted, disfigured; flowers greened. Containing red larvae. V. fruticans: Dasineura jaapi

8a Tip of generative or vegetative shoots severely stunted, organs densely clustered, variously disfigured; all green parts abnormally pubescent. V. alpina (incl. subsp. pumila), chamaedrys, fruticulosa, officinalis: Aceria anceps

8b Similar, ± strongly pubescent malformations on V. aphylla, fruticans require further analysis. Unidentified gall mite(s)

8c Vagrant mites on the underside of the leaves. At high densities the underside of the leaves may turn violet. V. chamaedrys, longifolia: Aculus latus

= This species is also reported as an inquiline of Aceria anceps

9a Galls locally, of more or less same shape, only rarely longer than 10 mm; on stems and leaves => 24

9b Malformations of largely indefinite shape, depending on organ; malformations of leaves and partially simultaneously on stems => 10

10a Malformations distinguished by excessive pubescence or down caused by branched conidiophores => 20

10b Malformations made conspicuous by rolling or curling of leaves, or spongy swellings on young plants => 11

11a Malformations of leaves, with or without involvement of stem => 12

11b Young plants severely stunted. Stem stunted, swollen, spongy. Surface of gall ± undulate, wrinkled, pale. Tissue brittle, necrotic. Swellings to various extent in closed or loose form on petiole, on the ± disfigured leaf blades as well as encroaching onto further developing stem parts. V. agrestis, arvensis, hederifolia, opaca, peregrina, persica, serpyllifolia, Pseudolysimachion spicatum, etc.: Ditylenchus dipsaci

= Also locally defined galls on stems and leaf veins of V. chamaedrys, persica might be attributed to this eelworm, causing minor damage – isolated galls on shoot parts – on young plants.

12a Various malformations caused by aphids, usually of several terminal leaves => 14

12b Malformations caused by spittlebugs, mites or thrips => 13

13a Upward rolls of leaf margin, containing single or several froth-covered nymphs. V. austriaca: Unidentified thrips

= Haplothrips aculeatus is reported as causer of such gall-like malformations

13b Leaves arched, with deflected margins, leaf blades curled and deep green close to infestation. Depending on leaf size, several to many, similarly disfigured leaves accumulated, almost nest-like, on ± stunted and distorted stems. Veronica spp.: Philaenus spumarius

14a Often minor, facultative malformations on various Veronica species are caused by various non-specific, differently coloured aphids, green, more rarely yellowish or reddish => 15

14b Similar malformations caused by black aphids. Veronica spp.: Aphis fabae

15a Antennae shorter than body, apterous aphids more or less dull coloured. Aphid 1–2 mm long => 18

15b Antennae of aphid as long as or distinctly longer than the very glossy body. Aphid often longer than 2 mm => 16

16a Siphunculi cylindrical or slightly conical, without swelling, 1/5–1/4 as long as body. Winged aphids with black head and thorax as well as with dorsal dark transverse stripes on abdomen, or only weakly pigmented => 17

16b Siphunculi in distal 2/3 distinctly swollen, 1/7–1/6 of body length. 1.6–2.0 mm, pale olive-coloured to greenish. Froth-covered milky coloured nymphs. Alates dark pigmented and with large, black central spot on abdomen. Veronica spp.: Myzus ascalonicus

17a Aphid pale straw-yellow, green or reddish; adult apterous often with dark spotted pattern. Siphunculi either completely or only terminally dark. Aphid about 1.9–3.1 mm long, alternating with Ribes species. Veronica spp.: Nasonovia ribisnigri

17b Light yellowish-green, base of siphunculi darker green. Siphunculi pale with blackish tip. Length 2–3 mm. Body pear-shaped, broadest distally. Veronica spp.: Aulacorthum solani

18a Siphunculi of apterous aphids black => 19

18b Siphunculi of apterous aphids yellowish-green with brown tip. Apterae rotund-oval, alternating with Rhamnus species. Veronica spp.: Aphis nasturtii

19a Siphunculi as long as cauda, body yellowish-green. Primary host Frangula dodonei. Veronica spp.: Aphis frangulae subsp. beccabungae

19b Siphunculi distinctly longer than cauda. All gradations from dark green to dirty-yellow are found in varying amounts. Veronica spp.: Aphis gossypii

20a Malformations covered with branched conidiophores => 22

20b The ± dense erinea consist of unbranched hairs of host plant => 21

21a Plant abnormally pubescent over extensive areas on leaves, stems and other green parts, sometimes additionally disfigured. V. alpina, chamaedrys, fruticulosa, officinalis, serpyllifolia: Aceria anceps

21b Similar, felt-like pubescence mainly on leaf blades. Paederota bonarota: Aceria bonarotae

22a Malformation of many leaves often over extensive areas ± etiolated shoots => 23

22b Malformations mainly on single or several terminal leaves, localised or expanded, bladder-like pale-green swellings. V. beccabunga, etc.: Peronospora grisea

23a On V. anagallis-aquatica: Peronospora aquatica

23b On other Veronica species. Depending on response ability of host, results in minor to ± distinct malformations. Conspicuous malformations only on early systemically infected organs, which show distinct etiolations:

a On V. agrestis, arvensis, chamaedrys, persica, polita, teucrium, verna:
Peronospora agrestis

b On V. hederifolia, triphyllos: Peronospora arvensis

24a Malformations bearing sori on their surface => 34

24b Galls without sori on their surface => 25

25a Single galls up to 3 mm long => 31

25b Galls usually longer => 26

26a Stem galls below the inflorescence or at least on the nodes of upper stem parts => 30

26b Galls predominantly on basal stem, exceptionally also on middle stem parts => 27

27a Causers are inside the galls => 28

27b Irregular spindle-shaped, sometimes curved swellings of variable length, with single or several rimmed depressions on their surface containing the causer. V. officinalis, chamaedrys: Planchonia arabidis

28a Galls with glabrous surface, containing larvae in chambers; V. serpyllifolia, Pseudolysimachion spicatum Galls with glabrous surface, containing larvae in chambers; V. serpyllifolia, Pseudolysimachion spicatum => 29

28b Stem with internodes or nodes with spindle-shaped, often ± curved and reddened swellings of variable length; surface of swellings undulately wrinkled. Causers inside galls. Similar, smaller galls sometimes on leaf veins. V. chamaedrys, etc.: Ditylenchus dipsaci

29a Shoots conspicuously stunted, in basal or middle parts with very irregularly shaped, about 3–7 mm long, nodular, one- to two-chambered galls. Each chamber containing a single larva. Mainly V. serpyllifolia: Gymnetron melanarium

29b Stem base, sometimes also root collar and upper root part, with conspicuous, rotund, up to about 12 mm long, one-chambered gall. Containing a single larva. Pseudolysimachion spicatum: Gymnetron erinaceum

29c Beetle larvae in locally strongly swollen stems. V. anagallis-aquatica: Gymnetron vittipenne

= Gymnetron aper has been reported as causing swelling of stem of V. officinalis

30a Shoot axis with spindle-shaped or acuminated, barrel-shaped to oblong cylindrical swellings, often distorted, up to 3 (4) mm thick. Smaller galls also on leaf- and flower peduncles, as well as on leaf veins; cells contain cinnamon-brown spore masses. Mainly on V. arvensis, hederifolia, triphyllos, also recorded from V. chamaedrys, filiformis, fruticans: Sorosphaerula veronicae

30b Shoot axis swollen below inflorescence. Pseudolysimachion spicatum: Jaapiella veronicae

= On Pseudolysimachion spicatum swollen leaf buds on stem (first midge generation) and flower buds (second generation) are caused by Dasineura spicatae

= Similar stem swelling, but associated with malformation of shoots or clustered flower buds, especially on higher growing species. Very variable galls of Jaapiella veronicae

31a Galls distinctly protruding at upper-, as well as on underside => 32

31b Leaf blade with rotund, up to 2 mm long spots, ± slightly swollen, at first dirty white, then brownish containing spores. V. serpyllifolia: Entyloma veronicae

32a Galls less than 1 mm across, wart-shaped; usually in large numbers on underside of basal leaves; sometimes on petioles and stems; solitary or joined, crust-like => 33

32b Leaf blade with reddish swellings on upperside. V. chamaedrys: Unidentified thrips

33a Multi-cellular warts, hemispherical, with depressed top. Nutritive cell with colourless content. V. anagallis-aquatica, beccabunga, chamaedrys, scutellata: Synchytrium globosum

33b Warts minute, coalescing into small brown-red spots. Galls simple, often hardly protruding; adjacent cells often not enlarged. V. scutellata: Synchytrium johansonii

34a Sori mainly on leaves, usually developing gregariously, protruding on underside, pad-shaped non facultatively – conspicuously swollen socket, covered with brown telia. Pads on leaf blade rotund, on upperside usually ± depressed; on venation oblong-oval to spindle-shaped on distinctly protruding bulges => 35

34b Sori usually ± elongate, chestnut-brown, mainly on variously distorted basal stem parts and on midribs on underside of more basal leaves. Spores glabrous or wall of upper cell with small warts. The mycelium developing telia usually expanded. V. alpina, aphylla, bellidioides: Puccinia albulensis

35a On V. montana, Pseudolysimachion spicatum, spurium. Sori pale brown, usually arranged in circles on sometimes weakly arched pads slightly sunken on upperside. Stalks of telia not brittle: Puccinia veronicae

35b Infestation similar. Sori developing in spring compact, pad-like arched on underside, depressed on upperside Teliospores thin-walled, with compact stalk. Sori with dark, thick-walled teliospores on brittle stalks develop in circles during summer. V. austriaca, ponae, Pseudolysimachion longifolium, spicatum, etc.: Puccinia albulensis

= The rare rust fungus Puccinia veronicae-longifoliae has also been recorded from Pseudolysimachion spicatum

36a On inflorescences or flowers => 39

36b Malformations on ovaries or fruits => 37

37a Ovaries unchanged outwardly. Malformation confined to ovula => 38

37b Ovaries strongly swollen, rotund-oval, sometimes with laterally ± shifted, arched, more rarely depressed apical part; galls ± globular, up to 6 mm across, wall succulent. Corolla and stamens dropping early. Containing a greenish tinged, dirty-yellow, black-brown headed larva, actively moving if disturbed. V. anagallis-aquatica, anagalloides, scutellata: Gymnetron villosulum

38a Stalk of ovary temporarily strongly swollen; other flower parts poorly developed. Tissue of entire ovary soon destroyed and filled with black, slightly brown-tinged spores. V. hederifolia, campylopoda: Schroeteria decaisneana

38b Ovaries temporarily swollen. Tissue inside soon replaced by a blue-grey to black-grey spore mass. V. acinifolia, agrestis, arvensis, persica, triloba, triphyllos, verna: Schroeteria delastrina

39a Flowers ± greened, leafy, also double or poorly developed, disfigured. Malformations often over ± extensive areas of inflorescence, sometimes abnormally pubescent. Caused by aphids or gall mites => 43

39b Flowers unopened, swollen => 40

40a Malformations caused by larvae which lack obvious, large head capsule => 42

40b Malformation mainly of the ovary caused by larvae with distinct head capsule => 41

41a In slightly swollen ovaries lives a seed-eating larva. Perianth of early infected flowers sometimes enlarged and unopened. V. beccabunga, scutellata, etc.: Gymnetron beccabungae

41b Also on V. anagallis-aquatica has been reported as causer of succulent ovary galls: Gymnetron veronicae

41c lowers unopened, swollen. V. arvensis, etc.: Gymnetron sp.

42a Flowers unopened, inflated, globular; each containing a single larva. When inflorescences are infected early, the largely undeveloped buds remain clustered, tuft-like; containing the orange-red coloured larvae. Veronica spp.: Jaapiella veronicae

42b Flowers swollen. Corolla slightly larger than calyx. Containing a single orange-yellow larva. V. anagallis-aquatica, beccabunga, scutellata, Pseudolysimachion spicatum, etc.: Dasineura similis

43a Malformations bearing aphids => 48

43b Malformations caused by gall mites => 44

44a Axis of inflorescence ± stunted; flowers variously disfigured => 47

44b Inflorescence not stunted or ± excessively branching; flowers disfigured => 45

45a Malformations without excessive branching => 46

45b Inflorescence ± excessively branched. Flowers ± greened or leafy, sometimes unopened, joined to almost cauliflower-like balls. Axial parts and calyx ± abnormally pubescent. V. chamaedrys, officinalis, prostrata, serpyllifolia, etc.: Aceria anceps

= Almost witches’ broom-like malformations with severely disfigured greened and leafy flowers on Pseudolysimachion longifolium could not be attributed to a particular cause

= Greening of flowers on V. persica is caused by viruses

46a Flowers double by multiplication of corolla leaves. In axils of corolla leaves sometimes short-stalked buds or similarly disfigured flowers. Stamens and ovaries aborted. V. officinalis: Unidentified gall mite

46b Flowers greened, calyx lobes ± enlarged and thickened. Paederota lutea:
Unidentified gall mite

47a Upper part of inflorescence with shortened midrib. Flowers ± greened. Bracts reduced. Pseudolysimachion longifolium: cf. Aceria anceps

47b Rachis of inflorescence and flower peduncles shortened, flowers clustered; calyx ± abnormally pubescent; other flower parts normal. V. alpina, bellidioides: Aceria anceps

48a Axis of inflorescence stunted and ± distorted. Flowers clustered, ± unopened, disfigured. Pseudolysimachion longifolium, spicatum: Aphis pseudolysimachiae

48b Stalk of inflorescence stunted. Flowers poorly developed; clustered, ball-like. V. anagallis-aquatica: Aphis frangulae subsp. beccabungae

gallers on Trifolium

pub 22.xi.2019

Dichotomous table for gallers on Trifolium

by Hans Roskam

1a On above ground organs => 4

1b On roots => 2

2a Roots with lateral nodules, or swellings situated on all sides in the root body => 3

2b Roots externally hardly changed, temporarily bearing about poppy-seed sized egg capsules (cysts), at first white, soon brown, which drop at maturity. Giant cells develop at the infestation site. Plant atrophied, with “starvation roots”. Trifolium spp.: Heterodera trifolii

3a Roots with nodular or slender spindle-shaped swellings on all sides, up to 6 mm long, bearing several lateral roots. T. alexandrinum, hybridum, incarnatum, pannonicum, pratense, repens, etc.: Meloidogyne hapla

3b Rotund-oval to slender cylindrical or forked nodules, also coralloid branched, up to 5 mm long, laterally inserted on main- or adventitious roots. Trifolium spp.: Rhizobium trifolii

4a On inflorescences, flowers or fruits => 25

4b On vegetative organs => 5

5a Localised malformations on stems, buds, leaves or more expanded malformations on single shoots => 6

5b Complete plant stunted, often excessively leafy. Shoots, also leaf- and inflorescence stalk stunted, usually spongy thickened at base; organs clustered, often distorted. Leaf blades reduced, swollen, sometimes extensively twisted, undulate or brittle. T. arvense, campestre, dubium, hybridum, incarnatum, medium, pratense, repens: Ditylenchus dipsaci

= Witches’ broom-like malformations lacking spongy thickenings on T. repens have been described as virus disease

6a Malformations on stems or leaves, caused by fungi, which develop their distinctive fruiting bodies at the surface of the host organs => 17

6b Galls caused by animals or by fungi, which fruit inside the host tissue => 7

7a Galls on leaf blades or -stalks, sometimes additionally also on stems => 12

7b Pronounced stem galls or malformations on buds => 8

8a Bud galls => 11

8b Stem galls => 9

9a Galls always on higher situated stem parts => 10

9b Stem with spindle-shaped swellings, up to 6 x 2.5 mm, on root collar or on higher situated parts. Containing a single larva. T. arvense, aureum, campestre, dubium, hybridum, pratense, spadiceum: Catapion pubescens

= Catapion curtisii has been recorded from oval swellings (6 x 3 mm) in root collar or root. T. fragiferum, repens

= Conspicuous proliferations on root collar by the polyphagous wood cancer Agrobacterium tumefaciens have also been reported for Trifolium

10a Galls spindle-shaped to ± cylindrical; sometimes developing to twice the stem diameter. T. hybridum, medium, pratense, etc.: Catapion seniculus

10b Stem often with several one-sided, almost hemispherical galls, sometimes clustered or coalescing. Each containing a single larva. T. arvense, pratense: Protapion varipes

11a End- or lateral buds transformed into a usually flattened egg-shaped gall, up to 8 mm long and 5 mm thick, succulent, one-chambered, yellowish-green, sometimes reddish at tip and ± enveloped by the associated enlarged stipules. Containing a rugose yellow larva with distinct brown head capsule. T. alpestre, arvense, aureum, campestre, medium, pratense, striatum, subterraneum, etc.:
Tychius polylineatus

11b Similar galls in lateral buds of T. medium and also T. fragiferum, purpureum, scabrum. Containing a single red midge larva. Dasineura axillaris

12a Single galls about 1 mm across, golden-yellow translucent, sometimes coalescing into crusts or ridges or hyaline to brown, 0.5–3 mm long. Caused by fungus => 16

12b Malformations larger => 13

13a Leaves ± folded and simultaneously variously twisted or curled => 15

13b Leaflets without particular curling, folded upwards over the midrib. Galls especially at midrib; their wall conspicuously or hardly thickened => 14

14a Galls bilge-like swollen; their wall conspicuously ± succulent to cartilaginous thickened, glabrous or slightly rugose, pale-green or reddened. Gall body on many hosts with ± broad, not thickened margin. Larvae at first white, later on orange- to reddish-yellow. Trifolium spp.: Dasineura trifolii

14b Galls restricted to the central part of the leaf blade, always surrounded by a broad margin of not thickened leaf blade tissue. Wall only slightly thickened, sometimes pale-green, also red discoloured, browned if mature. Containing 1–2 (3) pale yellow to pale orange-red larvae. T. pratense: Tricholaba trifolii

15a Leaf blade of leaflet folded together upwards or loosely rolled inwards; not or slightly thickened, twisted and ± undulately curled. Trifolium spp.: Aceria trifolii

= he gall mite Aculops eximius causes rust on mediterranean T. ochroleucon, pratense

15b Malformations of clustered leaves on locally stunted shoots caused by a froth-covered nymph. T. pratense: Philaenus spumarius

15c Leaves stunted; leaf blades of leaflets constricted, upwards ± folded together. T. dubium: Unidentified thrips

16a Galls consist of several cells, hemispherical, greenish-yellow, ± golden-yellow translucent, the depressed nutritive cell containing an overwintering sporangium about 160 (‒180) μm large; usually in large numbers mainly on the leaf blades of basal leaves, on their ± distorted stalks and sometimes on their lower stem parts. T. dubium. pratense, repens: Synchytrium aureum

16b Warts hyaline, 0.5–1 mm across, with sporangia and perennial spores. Galls unopened for a long period; later on rupturing in the middle; usually many on leaves as well as on the additionally disfigured stems, leaf- and inflorescence stalks. T. hybridum, incarnatum, montanum, repens: Physoderma trifolii

16c In similar galls on ± distorted leaves, leaf- and inflorescence stalks. T. hybridum, montanum, repens: Olpidium trifolii

16d Petioles and leaf veins, also inflorescence stalks, with several, usually elongate-oval, 2–3 mm long, soon discoloured black-brown, occasionally coalescing swellings; the bearing organs ± arched, bulging. T. fragiferum: Physoderma vagans

= Enatia on leaf undersides on T. incarnatum and other Trifolium species are caused by the Pisum-Virus I

17a The usually bulging galls bear yellowish aecia or dark coloured sori. Galls caused by rust fungi => 18

17b Leaf blades of developing leaves with inconspicuous weak archings, usually expanded, pale-green, bearing a down of branched conidiophores on leaf undersides. “False mildew”. The fungi which are ± frequent on several clover species are very specialised and may be assigned according to biometrical characters to the following micro-species:

a On T. alpestre: Peronospora trifolii-alpestris. – Minor swellings have sporadically been recorded

b On T. arvense: Peronospora trifoliorum. – Galls not observed

c On T. campestre, dubium, spadiceum: Peronospora trifolii-minoris. – Galls not observed.

d On T. hybridum, strictum: Peronospora trifoliorum. – This fungus exceptionally causes minor bulgings; especially on T. hybridum

e On T. medium, incarnatum: Peronospora trifoliorum. – Gall-like arching of leaf only rarely observed. Fungus especially distributed on the often conspicuously etiolated T. medium

f On T. pratense: Peronospora trifoliorum. – Fungus usually only in small pale-green spots on undersides of leaves that are not disfigured.

g On T. repens: Peronospora trifoliorum. – Occasionally the mycelium causes minor archings

18a Malformations bearing aecia, usually also other spore forms present => 22

18b Malformations bearing uredinia, or telia, no spermogonia or aecia => 19

19a Sori contain uredinia as well as telia => 20

19b Oblong swellings, sometimes associated with conspicuous distortions on underside of leaf veins or on petioles; bearing only telia. Mainly occurring on T. fragiferum, repens; also recorded from T. alpestre, arvense, aureum, dubium, etc.: Uromyces trifolii

19c Similar malformations are sometimes caused on T. repens: Uromyces trifolii-repentis

20a In addition to aecia, fungi also develop on sometimes distinctly different malformations, in some species also facultatively cecidogenic, spore forms on Trifolium species. Parasites not positively distinguished according to the malformations => 22

20b Fungi host alternating; develops only on the veins or stems on Trifolium, sometimes facultatively weakly cecidogenic uredinia and telia => 21

21a Sori usually mainly on leaf underside, scattered over the leaf blade, only causing minor swellings and sometimes distinct archings if developing on the venation. T. arvense, aureum, campestre, dubium, micranthum, striatum and close relatives: Uromyces striatus

21b Similar, minor malformations, facultatively on venation T. campestre, dubium, scabrum: Uromyces jaapianus

22a Fungi; all spore forms develop on Trifolium species. Telia only with warts, solitary or arranged loosely in rows => 24

22b Fungi do not develop uredinia => 23

23a Fungus mainly on T. montanum. Aecia often densely arranged in slightly swollen pads, especially on venation, up to 10 mm long. Also recorded from T. angustifolium: Uromyces minor

23b Fungus living on T. repens. Aecia on leaf veins and -stalks usually on distinct longitudinal swellings and malformations, occurring on leaf blades in small, circularly arranged groups: Uromyces trifolii

= Stems and leaflets bearing aecia, telia and uredinia on T. pratense, medium, incarnatum have been assigned to Uromyces fallens

24a Aecia only in spring, usually rare. Aecia mainly in elongated groups on underside of ± swollen and curved leaf veins, more rarely on bulges on petioles and stems; spermogonia usually on leaf upperside. Cups with whitish lacerate margin. Trifolium spp.: Uromyces trifolii

24b Aecia from spring to late autumn. Spermogonia occurring between aecia, often on same petiole. Cups circularly arranged in small dense groups; oblong on veins, leaf- and inflorescence stalks, often causing yellowish discoloured bulges and distortions. Peridium cup-shaped, with narrow, finely lacerate margin. T. repens, fragiferum, etc.: Uromyces trifolii-repentis

25a Localised malformations caused by fungi, gall midge larvae or snout beetles => 26

25b Extended malformation usually of many inflorescences. Flowers ± twisted; calyx teeth strongly developed; corolla stunted, disfigured, ± greened or also sometimes largely leafy, like the stamens and ovaries. T. arvense, aureum, campestre, dubium, hybridum incl. subsp. elegans, medium, montanum, pratense, repens, spadiceum, striatum: Aceria trifolii

= The flower thrips Frankliniella intonsa has also recorded from Trifolium.

= On several Trifolium species, especially T. repens, more rarely T. hybridum, incarnatum, pratense, occur conspicuously disfigured, greened, leafy inflorescences. These are caused by viruses, transmitted by cicadellids

26a Malformations contain larvae with distinct head capsule => 29

26b Malformations caused by midge larvae or fungi => 27

27a Galls inhabited by midge larvae => 28

27b Flowers unaltered externally. Ovary slightly stunted and swollen, sometimes covered with conidia. T. pratense: Thecaphora deformans

28a Flower buds in capitula where oviposition has been early are severely stunted. Corolla unopened and usually shorter than calyx teeth; like the calyx, distinctly swollen, especially at base. Sex organs atrophied. Inside at first white- to yellowish, at maturity pink-coloured larvae. T. pratense, medium, less frequently on T. hybridum and some other related species: Dasineura leguminicola

= In flowers of T. repens, more rarely T. hybridum, pratense lives the white clover midge Dasineura gentneri. Because this midge deposits eggs in already developed flowers, galls are not induced.

28b Similar malformation. The infected flowers are less swollen. Also these remain unopened, but the corolla surmounts the calyx teeth. Larvae orange- to ochre-yellow, jumping. T. pratense, occasionally also T. medium, hybridum, repens: Tricholaba trifolii

28c Yellow larvae in swollen flower buds. T. medium: Hadrobremia longiventris

29a Often only minor malformations mainly to parts of flowers; only secondarily sometimes also the midrib of the inflorescence => 32

29b Gall formation primarily affects the inflorescence axis => 30

29c Flowers greened, larvae living inside the stalk in a long corridor. T. repens, pratense: Hylastinus obscurus

30a Malformations of T. arvense, hybridum, ochroleucon, pratense, repens => 31

30b Inflorescence stalk terminally swollen to a small, asymmetrical gall. Containing a single larva. T. dubium: Protapion filirostre

31a Axis of inflorescence swollen. Calyx of affected flowers at first turgid. Containing single or several larvae. T. arvense, pratense, repens: Protapion dissimile

31b Similarly living on T. ochroleucum, pratense, more rarely on T. hybridum, repens, etc. are the larvae of Protapion dissimile

31c Infected inflorescences about a half times broader than normal ones; terminally truncated, otherwise looking normal, apart from the discoloured calyx which is often entirely pale-green. Containing 1 (2–3) larvae. T. arvense: Tychius pusillus

32a Inflorescences largely disfigured => 33

32b In often conspicuously damaged capitula, usually only single parts are galled. Gall-like malformations usually involving flowers on which eggs are deposited by snout beetles. Calyx often swollen, belly-like, on one side, the axis of inflorescence usually remains normal. Usually several larvae per inflorescence. Trifolium spp.: Apion div. species:

a Flower galls in disfigured inflorescences. Mainly on T. repens, also on T. aureum, hybridum, medium, pratense: Protapion fulvipes

b Flower malformations on T. repens, also on T. alpestre, medium, ochroleucon, pratense, rubens: Protapion trifolii

c In hardly disfigured flowers of T. repens, etc.: Protapion nigritarse

d In disfigured capitula with densely clustered flowers on T. medium, montanum, pratense might develop: Protapion varipes

e As inducer of bud galls on several Trifolium species has also been recorded: Holotrichapion pisi

= Larvae of the curculionid beetle Hypera nigrirostris may cause galls on clover

33a Young inflorescences, usually developing from axils or several flowers variously transformed into a uniform succulent gall. Infestation of larger, older flower buds results only in strong stunting of corolla and ± distinct bladder-like swelling of calyx. Containing a single yellow larva. Galls variable, depending on condition of host. On T. arvense mainly as bud gall; similarly also on T. subterraneum. Larvae also known from T. alpestre, aureum, campestre, medium, pratense, strictum. Tychius polylineatus

33b Inflorescence compact. The infected flowers soon transformed into a hardening, ± knobby mass. Containing several larvae. T. medium, montanum, pratense: Protapion apricans

gallers on Rumex

pub 22.xi.2019

Dichotomous table for gallers on Rumex

by Hans Roskam

1 On parts above ground => 9

1b On roots, rhizomes or root collar => 2

2a Rotund to spindle-shaped swellings containing causers in well-defined chamber or tunnel => 5

2b Galls compact, lacking chambers or feeding tunnels => 3

3a On roots => 4

3b Conspicuous, at first whitish, later on browned, succulent proliferations on root collar, eventually decaying. R. acetosella: Agrobacterium tumefaciens

4a Roots with slender spindle-shaped swellings, up to 7 mm long, sometimes bearing side roots. R. acetosella, crispus: Meloidogyne hapla

= Among the cyst developing Heterodera species, which cause development of giant cells inside roots, H. schachtii has been recorded

4b Expanded, globular, tuberous or ± barrel-shaped proliferations on roots, up to 20 mm thick and 30 mm long, which originate from enlarged and multiplied host cells. In cavities, together with many thick- and brown-walled, globular perennial spores, up to 46 µm large. R. scutatus: Physoderma ruebsaamenii

5a Swellings oblong or rotund, with single to several larval chambers => 6

5b Oblong, irregular expanded swelling on root, up to 15 mm long or more. Feeding tunnel elongate; containing a slender, dirty-white caterpillar with dark dorsal stripe and black-brown head. R. acetosella: Pyropteron triannuliformis

6a Galls more than 10 mm long, usually multi-chambered => 8

6b Galls only rarely up to 10 mm long, usually one-chambered => 7

7a Rotund, one-chambered or composite, multi-chambered galls on rhizomes, roots, rarely on root collar oblong, up to 10 mm long. Containing a single white larva. R. acetosella: Apion frumentarium

7b Oblong, rotund swelling on roots. Rumex spp.: Apion frumentarium

8a Galls on upper part of roots or root collar, very irregularly shaped, usually variously coalesced into tuberose, ± gnarled complexes, rotund- to oblong-oval, 10–30 mm long with several, irregular, crossing feeding tunnels. R. acetosella: Perapion marchicum

8b Swelling containing one or two chambers. R. acetosella: Apion rubiginosum

8c Irregularly rounded, succulent swellings on upper root part or on root collar, about 15 mm long and 10 mm thick, one- to multi-chambered. R. acetosa: Apion sp.

9a Galls restricted to single plant parts; on leaves, stems, inflorescences or fruits => 16

9b Gall development localised or diffuse, usually on several plant parts => 10

10a Galls caused by smut fungi, their pale- to dark violet spores translucent and dusty later on => 13

10b Galls induced by other causes => 11

= (Regarding malformations caused by animals living on host surface, see lead 29)

11a Causers develop inside galls => 12

11b Mycelium overwintering in rhizome, grows together with above ground plant parts and develops very dense, violet-grey down of branched conidiophores on completely covered leaf undersides, stem of inflorescence and flower parts. Diseased leaves are erect and rigid, leaf blades reduced, pale-green or reddened, slightly thickened, at margin usually distinctly rolled downwards. Inflorescences and flowers reduced, variously disfigured. R. acetosa, acetosella, alpestris, scutatus, thyrsiflorus, rarely crispus: Peronospora rumicis

12a Scattered swellings on basal-, more rarely on stem leaves, up to about 1 mm broad, flat, rotund, red-brown; coalescing on stems, often developing long knobby bulges. Rumex spp.: Physoderma majus

12b Young plants severely stunted, petioles and midribs, basal leaf blade parts, as well as stem primordia, including inserted organs, disfigured, pale green and thickened, spongy. Gall surface ± wrinkled. Later infestation results in development of ± localised galls on leaves and stems. R. acetosa, acetosella, crispus: Ditylenchus dipsaci

13a On several R. acetosa, acetosella, alpestris, thyrsiflorus, etc => 14

13b On R. longifolius, obtusifolius. Conspicuous, usually contiguous pustules, often on leaf margins; galls also on stems and especially on stems of inflorescences and flowers. Infected inflorescences usually completely diseased. Perigone, filaments and ovaries thickened and ± enlarged: Microbotryum warmingii

14a Malformations are inconspicuous swellings => 15

14b Infected plants largely diseased, often crippled, curved, usually sterile. Stem, inflorescence, petioles often distinctly shortened, ± distorted, conspicuously swollen to bloated, with many sori of dark brown-violet spore masses. Leaf blades often hardly unfolded, curved, main veins swollen, distinctly protruding on underside. R. alpinus, maritimus, obtusifolius, palustris: Microbotryum parlatorei

15a Weak swellings on leaves, stems, inflorescence stalks and flowers: Microbotryum kuehneanum

15b Sori inconspicuous, grey-reddish, in pale, thickened leaf blades and -stalks, only rarely in stems and flowers: Microbotryum goeppertianum

16a On inflorescences, flowers or fruits => 33

16b On vegetative parts => 17

17a On leaves => 20

17b On stems and stalks of inflorescences => 18

18a Galls ± spindle-shaped, 10–30 mm long, glabrous, tough-walled with central larval chamber => 19

18b Stem- or inflorescence axis at any point, and occasionally on all sides, weakly thickened; often many feeding tunnels in pith. Larvae whitish. R. acetosa, also on R. conglomeratus, crispus, nemorosus, obtusifolius, patientia, pulcher, etc.: Perapion violaceum

18c Rotund to irregular spindle-shaped swellings mainly of internodes, also on nodes and inflorescence axis, on all sides or sometimes on one side, 5–20 (30) mm long. R. acetosa, etc.: Perapion affine

18d In similar stem galls, e.g., on R. acetosella, hydrolapathum: Apion frumentarium

19a Short to extensive bulging swellings containing pale to dark-violet spore masses 13

19b Stem over variable length stunted on one or all sides and swollen, spongy. Surface ± wrinkled. If infected on one side then ± distorted. Side organs at infestation site clustered and variously galled as well. R. acetosa, crispus, obtusifolius: Ditylenchus dipsaci

20a Extensive malformations, even on large parts of whole leaf blades => 27

20b Gall formation at least of leaf veins, and -stalks or consists of locally restricted, ± rotund or oval galls on leaf blades => 21

21a Galls on leaf blade, often rotund, caused by fungi => 24

21b Spindle-shaped swellings on midrib, rarely on petioles, caused by animals => 22

22a Galls rather constant in size, spindle-shaped, surface glabrous. Containing causers in distinct cavities => 23

22b Midrib over variable length spongy, swollen, malformation ± encroaching onto neighbouring leaf blade areas, often pale-green, with wrinkled surface, Occasionally on petioles. Gall chamber absent. R. acetosa, crispus: Ditylenchus dipsaci

23a Midrib or petiole with spindle-shaped, yellow or red swelling, up to 10 mm long and 5 mm thick, often surrounded by a similar discoloured area. Containing an orange-coloured larva. R. acetosa, acetosella, crispus, ? hydrolapathum, patientia, thyrsoides: Apion frumentarium

23b Swelling in midrib or petiole; containing weevil larva or pupa. R. acetosella: Apion rubens

23c From similar galls on:

a R. acetosa, acetosella, etc.: Perapion curtirostre

b R. conglomeratus, sanguineus, etc.: Apion frumentarium

24a Rotund, more than 3 mm long, usually made conspicuous by red colouration, often hardly gall-like thickened pad caused by the aecia developing mycelium of rust fungi => 25

24b Less than 1 mm long, on the underside of leaf blade usually many flat, colourless, usually 1-celled small warts; also on leaf veins, -stalks. R. acetosa: Synchytrium anomalum

25a Aecidiospores 15‒21 x 12‒18 μm, orange-red when fresh, membrane uniformly with fine warts. Cells of peridium with narrow curved lumen; outer wall reaching far downwards => 26

25b Aecidiospores, diam.16‒26 μm, white. Membrane with fine and also scattered coarse warts. Aecidiosori on leaf underside on up to 10 mm broad, crimson-red, often yellow or pale red bordered spots, wide cup-shaped with white, deflected margin. Cells of peridium in longitudinal section with almost orthogonal lumen; outer wall with only short continuation downwards. Spermogonia whitish to pale-yellow, mainly on leaf upperside. On R. acetosa, etc.: Puccinia phragmitis

26a On R. acetosa, acetosella. Aecia on leaf blades on rotund, 2–5 mm broad, often crimson-red, hardly gall-like thickened spots, often arranged in a circle, mainly on leaf underside. Peridium whitish-yellow, with irregularly lacerate, hardly deflected margin. Sori on main veins and petioles, however, oblong-oval, on often distinctly swollen pads: Uromyces acetosae

26b On R. alpinus. Aecia like those of previous fungus. Spermogonia undescribed: Uromyces acetosae

27a Curling of leaf or –rolls caused by aphids => 31

27b Malformations of leaf blade by other inducers => 28

28a Caused by animals => 29

28b Caused by fungi. Leaves rigidly erect, leaf blades reduced, pale-green, margin ± narrowly rolled inwards, densely covered by grey-violet down of branched conidiophores on underside. R. acetosa, acetosella etc.: Peronospora rumicis

28a Leaf blade variously disfigured or rolled, caused by psyllids => 30

29b Leaf blade usually deflected over tip or laterally loosely rolled, strongly curled and deep green, especially at infestation site. Containing one or more froth-covered nymphs. Rumex spp.: Philaenus spumarius

29c Leaves wrinkled with erinea on underside. R. acetosella: Aculops macrotuberculatus

30a Restricted or extensive downward roll of leaf margin, ± thickened and leather-like. R. acetosella, acetosa, alpinus, scutatus: Trioza rumicis

30b Sorrels of Section Acetosa, Acetosella. Leaves variously disfigured, distorted, reddened, often with deflected margins. R. acetosa, acetosella, scutatus, etc.: Aphalara exilis

30b On Section Rumex, leaf curled downwards, discoloured; with small depressions each containing a froth-covered nymph. R. obtusifolius: Aphalara ulicis

= Furthermore the psyllid Aphalara purpurascens causing enclosed galls on disfigured leaves has been recorded. On R. aquaticus, conglomeratus, crispus, longifolius, obtusifolius

31a Leaf blade curled, also ± rolled or twisted => 32

31b Leaf blades rolled downwards over their length, tube-shaped. Rumex spp.: Aphis rumicis

32a Leaf blade parts strongly curled, irregularly rolled downwards at margin, leaf blade insignificantly thickened and swollen. Aphids black. Rumex spp.: Aphis fabae and/ or Aphis fabae subsp. solanella

= Bulging of leaf blades may primarily be caused by virus

32b Aphid green, leaves twisted, plant stunted, sometimes excessive leafiness. R. acetosella: Brachycaudus helichrysi

33a Galls restricted to flowers or their parts; axial parts only secondarily involved => 39

33b Malformation of ± large parts of inflorescence, flowers included => 34

34a Animal causers => 36

34b Malformations caused by fungi => 35

35a Inflorescence with all parts ± stunted. Buds clustered into dense groups, soon, like also the axial parts, covered with violet-grey down of branched conidiophores. R. acetosa, acetosella and relatives: Peronospora rumicis

35b Usually all flower buds of a plant swollen, variously disfigured. Inner organs soon destroyed by a black-violet, later on slightly dusty spore mass. R. acetosa, alpinus, thyrsiflorus: Microbotryum stygium

36a Caused by psyllids, larvae of beetles or gall midges => 37

36b Internodes stunted, side shoots and flowers ± densely clustered. R. thyrsiflorus, rugosus, etc.: Aphis acetosae

36c Inflorescences stunted; organs clustered like the neighbouring, disfigured stem leaves, bearing many reddish aphids. R. acetosella: Brachycaudus rumexicolens

36d Similar malformation on R acetosella: Unidentified aphid

36e Similar, but often much more extensive malformation. Rumex spp.: Philaenus spumarius

37a Causers live between or in stunted flowers => 38

37b Axis of inflorescence ± shortened and thickened. Flowers clustered, ± stunted and sterile. Containing beetle larvae. R. obtusifolius etc.: Apion sp.

38a Axis shortened; flowers densely clustered, little disfigured; bracts sometimes excessively developed. Between the flowers lives a psyllid. R. acetosella: Unidentified psyllid

38b Axis severely stunted; ± thickened, curved. Flowers clustered in dense balls, disfigured. Larvae reddish. R. acetosa, acetosella, etc.: Jaapiella rubicundula

38c Male flower buds contain midge larvae. R. acetosella: Contarinia rumicina

39a Galls mainly or exclusively on ovaries or fruits => 41

39b Ovaries distorted, gall consists of perigone => 40

40a Flower buds shortly stalked as result of infestation; therefore ± clustered, twice as large as healthy ones; oblong, irregularly bulging, yellowish to reddish. Stamens and ovaries distorted. R. acetosella, pulcher, maritimus: Contarinia rumicis

40b Galls similar. Larvae yellowish-white to orange-coloured. R. acetosa, acetosella: Contarinia acetosellae

41a Galls caused by animals => 42

41b Ovaries transformed into a conspicuous cylindrical or club-shaped gall, up to 3 mm long, 1 mm broad. Containing in nutritive cell 1–3 perennial spores with brown content. R. acetosella: Physoderma acetosellae

42a Malformations in outline ± oval, caused by gall midge larvae => 43

42b Ovaries usually greatly elongated, up to 25 mm long, transformed into a closed tube, or more rarely, with all transitions, into a ± stalked open funnel or cup. Often with 3 lobes at top. Perigone slightly enlarged. Stamens ± aborted. R. alpinus, scutatus: Trioza rumicis

43a Fruit or ovary, including flower, disfigured. Larvae between ovary and ± outwardly bent perigone, sometimes living in fruits. R. acetosella, obtusifolius, scutatus: Contarinia scutati

43b In similar malformations: Contarinia variabilis

gallers on Cirsium

pub 21.xi.2019

Dichotomous table for gallers on Cirsium

by Hans Roskam

1a On above-ground organs => 3

1b On roots => 2

2a Lateral roots with nodule-shaped, 2–3 mm across. C. arvense, oleraceum: Meloidogyne hapla

2b Main root or basal stem part with spindle-shaped swelling, up to 50 mm long and 10 mm thick. Contains a single larva. C. arvense, oleraceum, vulgare, etc.: Cleonis pigra

= The slightly cecidogenic caterpillar of Epiblema scutulana in stems and roots of various Asteraceae might also be responsible for root galls on Cirsium

3a On capitula or florets => 30

3b On stems or leaves => 4

3c Stems and leaves with white blisters, sometimes crust-like. C. oleraceum:
Pustula obtusata

4a Malformations restricted to single plant parts or to parts of shoots => 6

4b Malformations of expanded shoot parts of entire plants => 5

5a Plant completely stunted, ± disfigured; with expanded, or merely local, pale green, spongy swellings on all parts. C. arvense, oleraceum, tataricum: Ditylenchus dipsaci

5b Complete plant etiolated; development initially proceeding, later on stunted. Rosette leaves distinctly erect, lanky, usually non-flowering. Leaf blades narrowed, pale green, less spiny, occupied on both sides by many, sweet smelling widely distributed honey-yellow pycnidia, which are followed by initially reddish-brown uredinia and later on by black brown telia; only on C. arvense:
Puccinia punctiformis

6a Malformations exclusively or mainly on leaves => 10

6b Malformations predominantly on stems => 7

7a Swellings ± slender spindle-shaped => 8

7b Main- or side shoots with large, rotund or oblong multi-chambered swellings, about 10–50 mm long and 5–20 mm thick, initially green and succulent, later browned and woody. Each chamber contains a single larva. C. arvense, scattered on C. oleraceum: Urophora cardui

7c Facultative malformation of stem. Cirsium spp.: Ceratapion carduorum

8a Stem with extensive malformations => 9

8b Knob-like thickenings on root collar or on higher situated branchings. C. vulgare: Acanthiophilus helianthi

= All-sided, 10 cm long, inconspicuous stem swelling above the ground. Containing many amber-coloured puparia of an unidentified dipteran. Presumably a gall-like stunting caused by the larvae of a leafminer belonging to Melanagromyza

9a Stem terminally ± stunted and slightly thickened; tip of shoot stunted, closed. The pith contains a greenish, black-headed caterpillar. C. arvense, vulgare: Unidentified lepidopteran

9b On C. palustre. Swelling just below a clustered group of stunted capitula, containing a dirty red caterpillar: Epiblema scutulana

9c Stem over extensive parts usually spongy and swollen on one side, and sometimes distinctly curved. Galls with ± rugose surface, pale green; predominantly either close to the ground or close to the inflorescences. Cirsium spp.: Ditylenchus dipsaci

= The weevil Ceutorhynchus litura causes a malformation of 30–40 mm long on stem which becomes hardened and inflated, containing up to 12 larvae

10a Malformations with fungi fruiting on the outside => 28

10b Malformations caused by fungi fruiting on the inside of the galls, or caused by animal inducers => 11

11a Malformations of leaf margins or of leaf blades => 15

11b Malformations of the venation, sometimes ± widely extending into the unrolled leaf blade => 12

12a Galls restricted to the venation => 13

12b Main- or lateral veins to varied extents spongy, swollen and discoloured pale green together with their additionally sometimes ± clustered, also curled, surroundings. Cirsium spp.: Ditylenchus dipsaci

13a Main venation with ± extensive spindle-shaped swellings, situated predominantly on the leaf blade => 14

13b Midrib of the basal half of the rosette leaves slightly swollen. One to several larvae inside, tunnelling, more rarely mining. C. palustre, vulgare: Phytomyza continua

14a Galls spindle-shaped, usually brighter rimmed, with a single larva inside; gall rapidly collapsing and browning after the larvae have departed. C. arvense, tataricum, oleraceum, palustre, vulgare: Unidentified gall midge

14b Spindle-shaped bulges, about 2–12 mm long, yellowish to bright green, compact, glabrous, ± vitreous, sometimes in rows situated on the underside of the leaves; occasionally many small bulges on the basal stem parts. Sporulating close to the vascular bundle. C. oleraceum: Protomyces cirsii-oleracei

15a Leaves with either many, sometimes coalescing, hardly 1 mm long warts, or with very narrow rolls of the leaf margin => 24

15b Leaf blades with different malformations => 16

16a Extended malformations caused by aphids or cercopids => 20

16b Galls caused by other inducers => 17

17a Leaf blade with many small depressions or with pustule-shaped galls => 19

17b Leaf blades with irregular curls or folds => 18

18a Leaf margin ± folded or rolled, on the underside with several groove-like depressions, at first with a flat froth-covered nymph; leaf tip also folded, curled, or rolled. C. arvense, helenioides, oleraceum, etc.: Trioza viridula

18b Similar galls, on C. arvense, erisithales, heterophyllum, oleraceum, palustre: Trioza cirsii

18c Downward leaf roll, loosely undulate curled and tuberculate on the upper side. Leaf blade uneven, sometimes additionally with hairs. C. arvense, oleraceum: Trioza agrophila

19a Leaf blade with small depressions on the underside, with corresponding elevations on the upper side. C. helenioides: Trioza viridula

19b Leaf blade with green pustules. Containing a single midge larva. C. helenioides: Unidentified gall midge

20a Malformations caused by aphids => 21

20b Leaf blade, according to size, partially or completely and variously contracted; locally strongly curled and dark green. Infestation of young stems results in stunting, bending and clustering of neighbouring ± curled leaves. Cirsium spp.: Philaenus spumarius

21a Malformations caused by brown-black to dull black aphids => 23

21b Aphids yellow or dark red-brown => 22

22a Malformation of leaves caused by yellow aphids living on the underside. C. tataricum, oleraceum: Capitophorus horni

22b Aphid large, about 4 mm long, dark red brown, with transverse rows of black dots. Leaf blade curled, rolled, sometimes more densely haired. Heavier infestation may result in conspicuous stunting of young shoots. C. arvense, oleraceum, palustre, rivulare, vulgare: Uroleucon cirsii

23a Aphids about 1.5 mm long, brown-black, slightly powdered. Antennae half the body length. Siphunculi short, conical, slightly longer than cauda. Leaves rolled upward. C. oleraceum. pannonicum, ? canum: Aphis cirsiioleracei

23b Aphid about 2.5 mm long, dull black, rarely brown-black; antennae half the body length; siphunculi longer than the cauda. Affected leaves ± curled and bent downward. Strongly infected shoots variously stunted. Malformations not specific for the inducer. Following species host alternating, only distinguished by microscopical characters. Cirsium spp.:

a Aphis fabae s.s.

b Aphis fabae subsp. cirsiiacanthoidis

c Aphis fabae subsp. evonymi

24a Galls wart-shaped, consisting of several cells => 26

24b Roll of leaf margin => 25

25a Leaf margin narrowly rolled upwards and inwards. Larvae yellowish. C. oleraceum: Unidentified gall midge

25b Leaf margin narrowly rolled downwards and inwards. C. oleraceum:
Unidentified gall mite

26a Warts of conspicuous colour; content of nutritive cell yellow to red => 27

26b Content of nutritive cell colourless. Warts compact, vitreous green, pearl-like, often in large numbers on the underside of the leaves; sometimes coalescing into crystalline crusts. C. oleraceum: Synchytrium globosum

27a Galls compact, golden-yellow translucent; many on the underside of the basal leaves, scattered or ± coalescing. C. helenioides, oleraceum: Synchytrium aureum

27b Galls compact, reddish; on the underside of the rosette leaves, often coalescing into expanded yellowish- to blood red crusts. C. palustre: Synchytrium sanguineum

28a Sori with brown spores => 29

28b Sori with aecia, often several on the leaf underside, ± yellow or reddish margined; sometimes with oblong-oval shape on the major veins and only here facultatively inducing minor swellings. Cirsium spp.: Puccinia dioicae

29a Leaf blade on the underside with many small uredinia and telia. Fungus with two kinds of uredinia. The primary uredinia, accompanied by pycnidia, develop on the venation, sometimes on slight, bulge-like swellings. Cirsium spp.: Puccinia calcitrapae

29b Leaf blade with conspicuous sori, up to 5 mm wide, rotund, compact, initially yellowish-white, on the underside often clearly arched, soon coalescing bearing telia. Galls facultative. Cirsium spp.: Puccinia cnici-oleracei

30a Malformation primarily of receptacle. The gall causers are inside the host tissue => 34

30b Malformations of capitula or florets => 31

31a Capitula or florets hardly transformed => 32

31b Capitula usually enlarged, more rarely stunted, hardened, receptacle fleshy thickened. Florets greened or leafy. C. arvense. ? vulgare: Aceria anthocoptes

= Symptoms on capitula were also attributed to phytoplasma

32a Flower parts stunted or only slightly changed; malformations merely the results of inhibition rather than of gall induction => 33

32b Florets disfigured and discoloured; pistil thickened and lengthened, extending well above the florets. Containing red larvae. C. vulgare: Jaapiella compositarum

33a Florets stunted predominantly on one side of the ± twisted flower head. C. acaule, arvense, vulgare: Jaapiella cirsiicola

33b Capitula slightly stunted; florets hardly disfigured. Contain red larvae. C. arvense: Macrolabis cirsii

= Larvae of several gall midge species live between the aborted achenes on the receptacles of ± disfigured capitula of several Cirsium– and Carduus species. They hibernate in the decaying receptacles

33c Capitula with up to about 30 unilocular galls, 3 mm in across, with hard, lignified walls. C. ukranicum, also on Onopordum sp.: Isocolus cirsi

34a Larvae in or on the receptacle => 35

34b Capitula in the beginning ± spherically swollen, soon stunted and initially dark-violet, later brown, filled with dusting of spore balls. C. arvense, dissectum, helenioides, oleraceum, palustre, vulgare, etc.: Thecaphora trailii

35a Malformations caused by larvae without conspicuous head capsule => 36

35b Capitula almost normally developed. Receptacle somewhat thickened and hardened, contains one to several white larvae of snout beetles with brown heads, eventually also attacking the ovaries. C. arvense, dissectum, oleraceum, palustre, etc.: Larinus planus

36a Larvae cylindrical, with hook-shaped black mandibles; tephritid maggots => 38

36b Larvae slender, ± flattened, without conspicuous mandibles but with sternal spatula; gall midge larvae => 37

37a Receptacle swollen, hard, several chambers, containing red-yellow larvae. C. palustre, ? acaule: Unidentified gall midge

37b Capitula poorly developed, often oblique and twisted; stalks bent and buckled; flowers partially remaining closed; receptacle slightly swollen; several orange-red larvae. C. dissectum: Jaapiella cirsiicola

= Receptacles of many Asteraceae, especially in ± disfigured and stunted capitula of Cirsium- and Centaurea-species contain orange-red larvae of the saprophagous gall midge Clinodiplosis cilicrus. They invade hibernating and decaying receptacles which are earlier infected by other gall causers.

38a Receptacle completely or partially swollen => 39

38b Receptacle together with ± expanded parts or bearing stalks transformed into a slender, barrel-shaped, multi-chambered tough gall; florets completely withered. C. arvense: Urophora cardui

39a On C. eriophorum, erisithales, helenioides, etc. => 41

39b On C. vulgare, etc. => 40

40a Receptacle distinctly swollen, hardened, with several perpendicular oblong-oval chambers. Each chamber contains a single larva. Cirsium spp.: Urophora solstitialis

40b Receptacle thickened, hardened; containing several larvae. Urophora stylata

40c Furthermore in flower head galls of C. vulgare: Chaetorellia jaceae

40d Occasionally reported malformation of receptacles of Cirsium species. Larvae white with brown head capsule; black unsegmented pupal cocoons: Rhinocyllus conicus

41a On C. erisithales, helenioides, oleraceum => 21

41b On C. eriophorum. Receptacles often with several tough galls of different size, sometimes ± laterally coalesced and may expand over the whole receptacle. Many, usually perpendicular oblong-oval chambers, each containing a single larva: Urophora eriolepidis

41c In flower heads of C. eriophorum, spinossimum, vulgare: Urophora terebrans

42a Receptacle distinctly swollen, hardened. Containing several larvae: Tephritis conura

42b Receptacle conspicuously swollen, hardened, with several upright larval chambers. C. erisithales: Urophora congrua

42b Five more tephritid flies have been recorded from flower heads, viz., (1) Tephritis acanthiophilopsis from C. canum; (2) T. cometa from C. arvense, palustre, vulgare; (3) Terellia ruficauda from C. arvense; (4) Terellia longicauda from C. rivulare; (5) Terellia serratulae from C. vulgare, also on Carduus; all not true gall causers.

gallers on Centaurea

pub 20.xi.2019

Dichotomous table for gallers on Centaurea

(incl. Amberoa, Cheirolophus, Leuzea, Mantisalca, Rhaponticum)

by Hans Roskam

1a On above-ground parts => 4

1b On roots and root collars => 2

2a On main- and lateral roots => 3

2b Root collar with an often plurilocular fleshy swelling, up to 15 mm long. One larva per chamber. C. scabiosa, jacea, etc.: Isocolus scabiosae

3a Main root with spindle- or pear-shaped enlargement on all sides, up to 30 mm long, Containing one larva. C. jacea, stoebe, nigra: ? Pseudocleonus grammicus

3b Root nodule galls. Centaurea spp.: Ceratapion onopordi

3c Rarely developing oblong root galls which may contain a reddish-brown caterpillar with dark brown head capsule. C. jacea, nemoralis, etc.: Epiblema scutulana

3d Adventitious roots with small nodule-shaped swellings. Centaurea spp.:
Meloidogyne hapla

4a On capitula and fruits => 28

4b On vegetative parts => 5

4c Infested plants stunted, showing reduced growth, very bushy, with the apical parts of the stems and capitula still green and fresh during the hot and dry season, less spiny than usual, and producing less seed. C. solstitialis:

a Aceria solcentaureae

b Aceria solstitialis

c Aceria squarrosae

5a Plant parts with localised malformations caused by fungi or animals and with extensive malformations caused by animal parasites => 8

5b Complete plants or major plant parts etiolated; internodes ± elongated and lanky; leaves ± narrowed and paler; large areas of the underside occupied by fungal fruiting bodies => 6

6a Sori yellowish or brown => 7

6b Completely diseased shoots ± etiolated; also curved on one side. Especially the leaf undersides with expanded whitish areas of branched conidiophores. C. montana: Bremia centaureae

7a Shoot usually completely diseased; normally remaining sterile. The pycnidia and primary rugose uredinia soon also partially produce darker telia bearing mycelium which pervades the whole plant whilst deforming it. Secondary uredinia and later telia in dot-like sori are widely dispersed over normally shaped plant parts. C. montana, nervosa, nigra, phrygia, triumfetti, uniflora, etc.: Puccinia montana

7b Corresponding malformations with similar mycelium, completely pervading the plant; uredinia and telia confluent C. cyanus: Puccinia cyani

8a On leaves => 17

8b In buds, shoots or stems => 9

9a On stems => 11

9b In buds or shoots => 10

10a Leaves of the shoot tip of different length ± tuft-like stunted; leaf blades narrow, ± rolled, curled and often strongly pubescent. C. jacea, scabiosa, vinyalsii: Unidentified gall mite

= Extensive malformation of shoots of C. montana are caused by the aphid Uroleucon montanivorum

10b Shoot tip or lateral buds stunted, densely white-felt-like pubescent, somewhat thickened at base. Leaf blades of further developing leaves with irregularly distributed covers on both sides. One or several yellow-red larvae. C. jacea, montana, triumfetti: Dasineura centaureae

11a Malformations predominantly of the stems => 12

11b Younger stems locally stunted and sometimes curled; leaves stacked, nest-like converged; leaf blades curled and locally dark green. Shoots sometimes deformed over larger parts. C. cyanus, jacea, montana, nigra, etc.: Philaenus spumarius

12a The gall causers live inside the stem => 13

12b Stems with bulging swellings over various lengths. Galls ± strongly bent, solitary or with several ridges framed by depressions, which contain the gall causer. C. scabiosa: Planchonia arabidis

13a Galls caused by insect larvae => 14

13b Stem, also neighbouring leaf stems, of young plants with pale green, spongy, sometimes curved swellings which may differ in their respective lengths. C. cyanus, Amberoa moschata, etc.: Ditylenchus dipsaci

14a Swellings inconspicuous or absent => 15

14b Stem with conspicuous swellings => 16

15a Outside of stem hardly changed. Galls only visible after dissection; inside of stem usually with several oval, tough-walled larval chambers, up to 5 mm long and 1 mm wide, each with one larva protruding into the pith. C. aspera, diffusa, jacea, micranthos, nigra, phrygia, stoebe, scabiosa: Phanacis centaureae

15b Galls in stems in a form of rounded or elliptical cells in the parenchyma; the stem sometimes slightly malformed. C. adpressa: Isocolus volgensis

15c Similar gall. C. adpressa, orientalis: Phanacis crassinervis

15d Similar gall. C. adpressa, orientalis: Phanacis varians

15e Upper part of the young stem especially stunted in longitudinal direction; basal part slightly spindle-shaped swollen over a length of 3–4 cm. A long, narrow larval chamber in the pith, contains a single caterpillar. C. stoebe, scabiosa: Unidentified ? lepidopteran

= The caterpillar of the leafroller Epiblema scutulana lives in the capitula of several Asteraceae but without causing galls. However, those of the next generation infest the stems and roots of C. jacea and is reported as a gall causer of stems for C. nemoralis

16a Stem in different extensions, sometimes over a length of 10–15 cm, irregularly crookedly swollen. The inside with many solitary or gregariously situated oval, tough-walled larval chambers each containing one larva. C. scabiosa incl. subsp. sadleriana, etc.: Isocolus scabiosae

16b Conspicuous more or less globular one-sided swelling, multi-chambered. C. aspera: Isocolus latreillei

16c Similar usually smooth swelling. 20–25 x 15–18 mm. C. aspera, melitensis, Mantisalca salmantica: Isocolus lichtensteini

16d One-chambered swelling on stem base. C. aspera: Isocolus fitchi

16e Stem strongly swollen and buckled some distance below the flower head. Containing several orange-coloured larvae. C. decipiens: Unidentified gall midge

17a Rotund to oval, only slightly cushion- or callus-like swellings, which are soon occupied by the yellow or brown sori of rust fungi => 25

17b Malformations caused by other gall causers => 18

18a Malformations predominantly of the leaf blades => 21

18b Galls on the midrib or on veins of main- or lesser order => 29

19a Galls not extending onto the leaf blades => 20

19b Veins of different order, more rarely also the midrib or petiole, regularly with solitary rotund-oval or spindle-shaped galls, but also in rows situated gregariously, in the leaf blade extending and visible on both sides. Wall fleshy to cartilaginous, ± pale green. Area around the galls often yellowish or purple coloured. Containing a single yellow larva. Centaurea spp.: Loewiola centaureae

20a Midrib or petiole with rotund, tough-walled, unilocular swelling, up to 8 mm long, visible on both sides. Containing a single larva. C. scabiosa: Isocolus fitchi

20b Midrib in the middle of the leaf blade with lemon-shaped, tough-walled swelling containing a large chamber; terminal part of the spindle recurved. Containing a single larva. C. stoebe: Unidentified gall wasp

21a Malformations by aphids or cercopids => 23

21b Galls small, usually many, wart- or pock-like => 22

22a Leaf blades, especially of basal leaves, with ± rotund-oval lenticular pocks, 1.5 to 2.5 mm long, visible on both sides, often bright green, also reddish to black violet with a fine opening on the upper side. Centaurea spp.: Aceria centaureae

22b Basal leaves on the underside with many semi-globular, golden yellow gleaming, pearl-like warts, hardly 1 mm long. C. jacea: Synchytrium aureum

= The chytrid Synchytrium solstitiale occurs with many orange red warts, up to 0.2 mm across, on the leaves of C. solstitialis. that often are more or less distorted. In a later resting stage the warts are grey

23a Leaf rolls caused by aphids => 24

23b Leaf blades, according to leaf size, completely or partially nest-like deflected; curled mainly close to the site of attack and dark green. Centaurea spp.: Philaenus spumarius

24a Leaves of several shoot tips often rolled over their length. Aphid bright yellowish to yellow-green. C. cyanus, paniculata: Brachycaudus helichrysi

24b Similar malformations caused by black aphids. C. calcitrapa, stoebe, etc.: Aphis fabae

25a Callosities or cushions with brown sori => 26

25b Swellings or hardly thickened areas on the leaf blades bearing aecia and usually also pycnidia. Galls facultatively; on the same host often developed to a different extent, ± reddish coloured. Aecia on underside of leaf, in rotund yellow- to crimson red bordered sori. Peridium broadly deflected, with irregularly incised border. C. nigra: Puccinia arenariicola

26a Minor swellings of leaf veins or petioles, ± rotund-oval, facultative gall causer; only in spring and ± solitary. Only produced by the primary mycelium bearing uredinia and partially also pycnidia. The far more frequent much darker secondary uredinia and telia, produced in little sori, are not cecidogenic. Fungus with various biological forms => 27

6b Leaf blade with rotund compact red brown cushions about 2–5 mm long, often many and usually protruding on the leaf underside, often yellow-bordered. Sori, when on the veins ± oblong-oval; exclusively with densely set, glabrous, 2-celled, dark brown telia. C. scabiosa, also jacea, kotschyana, maculosa, montana, phrygia, etc.: Puccinia verruca

27a Leaf blade on underside develop sori with aecia, often several on the, ± yellow or reddish margined; sometimes with oblong-oval shape on the major veins and only here facultatively inducing minor swellings. Centaurea spp.: Puccinia dioicae

27b Leaf blade on the underside with many small uredinia and telia. Fungus with two kinds of uredinia. The primary uredinia, accompanied by pycnidia, develop on the venation, sometimes on slight, bulge-like swellings. Centaurea spp.: Puccinia calcitrapae

27c Uredinia with two terminal germ pores, warts not developed over the spore surface On C. jacea, etc.: Puccinia hieracii

27d Close to this species is the fungus on Rhaponticum scariosum, occasionally on the veins on the upper side with primary large sori, up to 15 mm long, which are slightly swollen and curved, sometimes accompanied by pycnidia: Puccinia centaureae-rhapontici

27e Uredinia with three equatorially situated germ pores, also with loosely placed fine warts here, as well as on the remaining surface of the spore. Especially on C. scabiosa, but also on many other Centaurea species: Puccinia carthami

28a Galls in ovaries or fruits, capitula externally hardly or not markedly changed => 38

28b Malformations in other parts of the capitula => 29

29a Gall causers are found in the receptacle => 36

29b Malformations in flowers or in the scales of the involucre => 30

30a Substantial parts of the capitula malformed => 31

30b Scales of the involucre of the otherwise not markedly malformed capitula at the base with an oblong-oval, up to 7 mm long and 4.5 mm wide, single-chambered, tough-walled, glossy bulge. Containing a single larva. C. scabiosa: Isocolus rogenhoferi

30c On C. adpressa, solstitialis. Gall at the base of the flower head and/ or on the stem below it. In many cases no deformation of the flower head base and stem was observed and only single galls were found in each infected flower: Isocolus ponticus

30d Same hosts. A large number of galls are developing in one flower head, and these strongly deforming and enlarging the flower head and the stem below. The galls are merging together and forming a hard, lignified conglomerate at the base of the flower head: Isocolus tauricus

30e On C. ruthenica. Galls are formed at the base of flower heads. Usually 8‒10 galls form a conglomerate, up to 30‒35 mm in diameter and, thus the base of a galled flower head is usually enlarged, swollen. Mature galls are lignified, thick-walled, brown: Isocolus ruthenicae

30f On C. (Phaeopappus) trinervia. The usual gall wasp induces galls at the base of flower heads: Isocolus phaeopapucii

30g On Leuzea conifera. Galls inside flower heads. Isocolus leuzeae

30h On C. diffusa, pseudomaculosa, virgata subsp. squarrosa. The galls lie between the involucral bracts and eventually fall off. They are unilocular, 2 mm long, elliptic; the wall is thin, lignified and slightly rough: Isocolus centaureae

30i On C. orientalis. Galls in the capitula, between the achenes: Isocolus flavus

31a Capitula malformed, ± stunted and remaining closed => 33

31b Capitula enlarged, ± wide, gaping. Flowers not developed, malformed, succulent, thickened => 32

32a Ditto on C. bracteata, decipiens, micrantha, scabiosa subsp. sadleriana stoebe: Aceria grandis

32b Ditto on C. jacea: Unidentified gall mite

32c Ditto on C. aspera: Aceria brevisetosa

32d Capitula swollen, malformed, spines reduced. C. aspera: Aceria calathidis

32e Inconspicuous swelling of capitula. C. aspera: Larinus longirostris

33a Malformations caused by gall mites => 34

33b Development of capitula together with their organs remarkably stunted, containing several, usually orange-yellow larvae. C. scabiosa: Dasineura miki

34a Capitula severely stunted, only about 5 mm long and ± disc-shaped, abnormally haired together with the neighbouring parts of the shoot. C. scabiosa: Unidentified gall mite

34b Capitula stunted, remaining ± closed. Flowers ± greened and haired. C. decipiens: Unidenified gall mite

34c Similar, ± greened, but hardly haired, pea-sized malformations of capitula. C. phrygia: Aceria centaureae

35a Extensive parts of receptacle swollen, hardened, with several oblong-oval, perpendicular to the surface, rarely ± inclined larval chambers. Infected capitula often more globular than normal ones. One maggot per chamber with abruptly humped back: various tephritid flies

35b Ditto, with distinct head capsule => 36

36a Beetle larvae feed on flower head; these only malformed on one side, development stunted, ± distorted or skewed. C. jacea, scabiosa, etc.: Larinus planus

= Beetle larvae of Larinus minutus feed on the developing achenes, and pupate in the partly eaten receptacle. Not a true gall. C. diffusa, stoebe.

36b Similar malformation by caterpillars. C. nigra, scabiosa, etc.: Unidentified lepidopteran

= The larvae of the gelechiid moth Metzneria metzneriella are frequently found in the capitula of many Centaurea species, but do not cause galls

37a Fruits ± swollen or elongated, caused by larvae of cynipids which are narrowed at both ends => 38

37b Fruits inconspicuously swollen, slightly elongated. The gall includes occasionally, in the case of young flowers, the under part of the lightly greened corolla tube. Containing a plump, conical, terminally blunt white larva with black mouth parts. C. jacea: Urophora jaceana

38a Fruits oval, up to 8 mm long, swollen, tough-walled, woody; one larva. C. scabiosa: Isocolus scabiosae

38b Fruit weakly swollen, up to 4.5 mm long. Gall tough-walled, ± connate to the receptacle. Containing a single larva. Adult with indistinct carinae on anterior part of mesonotum (comp. next lead). C. jacea, montana, paniculata, stoebe, scabiosa, etc.: Isocolus jaceae

gallers on Rubus

pub 19.xi.2019

Dichotomous table for gallers on Rubus

by Hans Roskam

1a On above-ground parts => 3

1b On roots, on root collar or on basal stem parts => 2

2a Roots, root collar or basal stem parts with irregular proliferations, up to 20 mm long, at first succulent, later on lignifying, ± globular, rough on the surface, without gall chamber. Rubus spp.: Agrobacterium tumefaciens

2b Young roots of R. idaeus with several swellings, 1–2 mm long, approximately urn-shaped, with fungus mycelium interspersed: Mimeuria ulmiphila

2c Small solid swellings, often curved and twisted, at the tips of lateral roots; other parts of roots sometimes thickened; adult eelworms slender and transparent, 1.5–12 mm long; feed on outside of root (so, often are not seen): Longidorus sp. and/ or Xiphidinema sp.

2d Stem base, also roots, with elongated swellings, up to15 mm long, brownish. Pith containing a whitish, black-headed caterpillar. Rubus spp.: Pennisetia hylaeiformis

3a On flowers and fruits => 32

3b On vegetative plant parts => 4

4a On shoot tips or leaves => 8

4b On stem parts => 5

5a Younger or older axis with conspicuous strong swellings => 6

5b Younger, and even lignified shoots with elongate spindle-shaped swelling, which displays a screw-like tunnel around the shoot. R. idaeus, fruticosus: Agrilus cuprescens

5c Salmon pink larvae live under rind. Attacked stem may die back. R. idaeus: Resseliella theobaldi

6a More or less globular, one-sided proliferations or spindle-shaped nodular swellings on the branches => 7

6b Oblong, about 30–80 mm long, and up to 10 mm broad, multi-chambered, with bumpy -tubular swellings, enclosed by glabrous bark. Each chamber containing a single white larva. Rubus spp.: Diastrophus rubi

6c Similar gall. R. idaeus: Aulacidea rubi

7a One-sided protrusions, more or less globular up to 30 mm long, at first succulent, white, later on browned and lignified compact proliferations with tubular surface, usually originating from bud primordia of young lignified stems. Galls sometimes coalescing ridge-like. Rubus spp.: Agrobacterium tumefaciens

= Irregular proliferations, at first short, later on usually extending over several internodes, erupting from bark, pale-green, free from parasites, mainly on two-years old, often additionally swollen shoots of R. idaeus, occasionally also on bramble. Often teratological malformations, predominantly on branches weakened by parasites

7b Rotund to constricted barrel-shaped swelling, mainly one-sided, about 10–20 (50) x 5–7 (20) mm; later woody with rough fissured bark. Inside are many larvae, at first white, later on orange-red. Rubus spp.: Lasioptera rubi

7c Inconspicuous localised swelling. R. fruticosus, idaeus: Agrilus cuprescens

8a Malformations on shoot tips or expanded parts of leaf blade disfigure => 20

8b Localised galls on leaf blades, of ± defined shape => 9

9a Galls almost exclusively on leaf blade parenchyma => 14

9b Galls almost exclusively or mainly on leaf veins, -midrib, -stalk; sometimes only conspicuous by discolouration of leaf blade => 10

10a Venation or axis with bulge-like thickening of various size, soon covered with fungus fructifications => 11

10b Main- or lateral veins of leaflets with swellings 5–7 mm long, 2–3 mm broad, stronger on underside, less protruding on upperside, almost completely filled with larvae and collapsing after their departure. Neighbouring leaf blade parts at first hardly discoloured, after vacation usually yellowish, rarely reddish tinged, occasionally interspersed by a violet-black discoloured venation over a length of 20–30 mm and width of about 12 mm. Larvae conspicuous large, white, sulphur-yellow later on, often greenish translucent. R. idaeus: Buhriella rubicola

11a More or less distinct, facultative yellowish bulges on main venation, on leaflet- and petioles, occasionally also on young shoot stems. In the leaf blades are small rotund patches with spores developing on underside, and sometimes on upper side. Possible gall formation in spring by caeoma-sori of monoecious rust fungi. On. R. arcticus, idaeus, saxatilis => 13

11b Analogous malformations on other Rubus species => 12

12a Aecia with large disc-like warts; mainly developing in often red-margined sori on underside; uredinia rather densely-spiny, teliospores mainly 6-celled, with awl-like tip at apex. Rubus spp.: Phragmidium bulbosum

12b Aecia and uredinia with distantly spiny-warts; telia usually 4-celled, with blunt papilla at apex; developing on often violet-red margined sori. Rubus spp.: Phragmidium violaceum

13a On R. saxatilis: Phragmidium acuminatum

13b On R. arcticus, arcticus x saxatilis, with similar biology, Phragmidium arcticum

14a Galls 2 mm long or less => 16

14b Leaf blade either with expanded rotund pads caused by fungi or with expanded erinea caused by mites on underside => 15

15a Leaf blade with weak, ± yellow, sometimes red-margined, pad-like swellings. Sori either on upper- or underside => 11

15b On underside often with many, locally, slightly expanded rotund depressions with white erinea; on upperside not or only slightly protruding. Hairs ± curved, spirally; erinea sometimes coalescing, but not extending into other organs. Rubus spp.: Eriophyes rubicolens

16a Galls nodule or pustule-shaped, visible on both sides of leaf, caused by animals => 18

16b Galls wart-shaped, one-sided, caused by fungi => 17

17a Warts golden-yellow, many-celled. R. caesius, dumetorum: Synchytrium aureum

17b Warts almost colourless. Galls 1-celled. R. arcticus: Synchytrium myosotidis var. potentillae

18a Galls pustule-shaped, conspicuously shrunken. “Procecidia”, oviposition scars, not true galls => 19

18b Rotund nodules, protruding on both sides, 2 mm across. Exit small, usually on underside, rarely on upperside and then cup-like. With club-shaped or cylindrical hairs inside proliferations, R. arcticus, saxatilis: Aceria silvicola

19a Pustule-shaped egg capsules between leaf dentition. R. fruticosus, idaeus: Arge gracilicornis

19b Egg-shaped “procecidia”, oviposition scars, not true galls, 1.5 mm long, yellow swellings, visible on both sides, often with several together, in the axils of ± curved veins. The emerging larva leaves the gall and lives free on the leaf surface. R. corchorifolius: Unidentified sawfly

20a Malformations mainly of several terminal leaves, caused by aphids => 26

20b Various malformations of single or several terminal leaves by other causers (for witches’ broom-like malformations => 21

21a Malformations sometimes expanded, ± pubescent or glabrous => 22

21b Expanded parts of leaf, shoot- and inflorescence axis, flower peduncle, possibly flower buds, and the green parts of ± opening flowers and even the almost mature, already black-violet coloured mericarps with velvet-like greyish pubescence. Early infected leaves stunted, with curved venation. Hairs cylindrical, acuminate, rigid and longer than the normal ones. Rubus spp.: Epitrimerus gibbosus

22a Galls caused by animals => 24

22b Galls caused by parasitic fungi => 23

23a Leaf blade with yellow, slightly thickened spots, which bear on the upperside spermogonia and on both sides, golden-yellow, primary uredinia arranged in rings. R. caesius, fruticosus, hirtus, nemorosus, plicatus, etc.: Kuehneola uredinis

23b Infected leaves ± disfigured, usually smaller and paler than the healthy ones. In autumn and spring on underside, accompanied by spermogonia, caeoma-sori. R. arcticus, saxatilis: Gymnoconia nitens

23c Similar malformation. R. arcticus, canadensis, chloocladus, leptadenes, saxatilis: Arthuriomyces peckianus

24a Leaflets variously folded upwards and additionally further disfigured => 25

24b Leaflet ± abruptly bent, deflected over the top, close to the infestation site strongly crumpled, dark-green. Rubus spp.: Philaenus spumarius

24c Localised malformation of leaf blade. R. fruticosus: Trioza tripunctata

25a Leaflets folded upwards along ± thickened main veins, undulately curled and often ± discoloured; stunted and sometimes more densely pubescent; several white larvae briefly between folds. Rubus spp.: Dasineura plicatrix

25b Midrib and side veins of first and second order bent in and out. Leaf blade folded, folds scantily pubescent, usually discoloured on underside. Malformations only exceptionally conspicuous, leaf blades ± arched. R. idaeus and many other brambles: Phyllocoptes gracilis

25c Similar, only exceptionally gall-like damage on R. caesius, candicans subsp. thyrsoideus and cultivated relatives: Anthocoptes rubi

25d Vagrant mites on the underside of the leaves. At high densities some discolouration may occur. R. laciniatus: Anthocoptes rubicolens

26a Aphid greenish => 27

26b Populations of green and brownish-red aphids usually present. Siphunculi thin and long, about a third of body length. R. caesius and other brambles: Macrosiphum funestum

27a On raspberry (R. idaeus) and various brambles, R. caesius, fruticosus, etc. => 28

27b On R. saxatilis: Aulacorthum cylactis

28a On brambles => 30

28b On raspberries => 29

29a Leaves weakly arched: Amphorophora idaei

29b Leaves variously crumpled, with several bunched together in relatively compact clusters. Aphis idaei

30a Leaves relatively loosely arched and weakly rolled. Minor stunting of shoot. Malformations only facultative. Aphid yellowish-green to green. Adults larger than 2.5 mm => 31

30b Leaves strongly rolled inwards in spring; aphid also living on green shoots in dense colonies. Aphis ruborum

31a Siphunculi cylindrical and often dark-brown. Antennae slightly shorter than or almost as long as body: Sitobion fragariae

31b Siphunculi slightly swollen, colourless, with thin tip. Antennae longer than body: Amphorophora rubi

= Virus diseases occur widely on Rubus species, especially raspberries, causing mosaic-like discoloured malformations of leaves, as well as curling of many leaves on ± severely stunted shoots

32a On inflorescences or flowers => 33

32b Receptacle thickened. R. idaeus: Unidentified ? tephritid fly

33a Malformations of flowers only => 34

33b All parts of inflorescence with abnormal silvery pubescence. Rubus spp.: Epitrimerus gibbosus

34a Flowers conspicuously greened, leafy or developed further => 36

34b Flowers unopened, variously disfigured => 35

35a Flowers unopened. The calyx, sometimes appearing enlarged, encloses the other, usually smaller, ± disfigured inner flower organs. Many ivory-white to yellowish jumping larvae per bud. Infected flowers soon dropping. Rubus spp.: Contarinia rubicola

35b Corolla stunted, abnormally developed, ± greened. Sex organs reduced; at first greened, later on browned. R. fruticosus: Unidentified thrips

35c Bud swollen, unopened, containing beetle larva. R. ulmifolius incl. vars: Anthonomus rubi

36a Flower organs mostly greened, transformed into small green structures. R. fruticosus: Acalitus essigi

36b Flowers conspicuously and variously disfigured, greened, leafy, sometimes developed further. Rubus spp.: Virus disease

= Cause of the malformations associated with enlargement of calyx in raspberries and brambles is the well-known “Rubus-branching virus”, which may also induce a witches’ broom-like dwarf growth

gallers on Rosa

pub 18.xi.2019

Dichotomous table for gallers on Rosa

by Hans Roskam

1a On above-ground parts => 3

1b On roots or root collar => 2

2a Roots with spindle-shaped swellings. R. canina, multiflora: Meloidogyne sp.

2b On roots or on root collar, expanded, at first succulent, then lignifying proliferations with tuberculate surface. Rosa spp.: Agrobacterium tumefaciens

2c Small solid swellings, often curved and twisted, at tips of lateral roots; other parts of root sometimes thickened; eelworms live externally in soil, not often seen. On Rosa cultivars: Xiphinema diversicaudatum

= The red bud borer Resseliella oculiperda damages rootstocks of cultivated roses and apples when these are grafted with scion buds by “shield budding”

3a Fruit variously disfigured, often ± etiolated. Rosa spp.: Rhagoletis alternata

3b On vegetative plant parts => 4

4a Malformations of various extent caused by fungi, which produce brownish or whitish sori on the gall surface, soon yellowish to orange => 29

4b Malformations induced by other causers => 5

5a Galls on various plant parts, distinguished by moss-like proliferations or swelling of stem bearing bushes of mistletoe => 28

5b Malformations different => 6

6a Galls never closed on all sides, only on leaves; leaf blades folded, rolled, curled, with erinea, or with egg capsules on petioles, leaf blades or between leaf teeth => 19

6b Malformations different; on stems or leaves => 7

7a Malformations closed on all sides, with single or several tough-walled chambers => 13

7b Galls without chambers; only on shoot axis => 8

8a Minor, soon fragile swellings on young shoots caused by egg batches of sawflies (procecidia, oviposition scars, not true galls) => 12

8b Malformations exist for a longer period => 9

9a Causer not recognisable from the outside => 10

9b Bark with small, bulging rimmed depressions, containing causer below a flat, 2.3–3 mm long scale. R. canina, eglanteria, pomifera, villosa, etc.: Chionaspis salicis

9c More expanded malformations bearing Viscum album

10a compact or cancer-like malformations => 11

10b Young lignified shoots slightly swollen over a length of 30–50 mm. The swelling contains a tunnel in the inner bark running in relative narrow turns around the axis. R. x damascena, rubiginosa, x rugosa. spinosissima, etc.: Agrilus cuprescens

11a Axis of older shoots or young stems often with many walnut-size, at first succulent, then lignifying proliferations, mainly close to a node. Rosa spp.: Agrobacterium tumefaciens

11b Infestation sites depressed to varied extent, on reactive young twigs rimmed by flat to almost cauliflower cancer-like proliferations. Proliferations at first dirty-white to yellowish, then browned. “Bark spot disease”. Rosa spp.: Coniothyrium wernsdorffiae

= Similar damage may be caused by the widely distributed, also known from other hosts, equally hardly cecidogenic sac fungus Leptosphaeria coniothyrium

12a Egg capsules arranged in two rows. bark often ripping open and sometimes more or less rimmed later on. Rosa spp.: Arge pagana

12b About 16–18 egg capsules, arranged in one row, just below shoot tip, soon bending, occasionally browning and withering. Rosa spp.: Arge ochropus

13a Galls smaller than 10 mm => 14

13b Galls often larger, usually irregular, bulbous and bumpy, up to 25 (40) mm long. Wall not very tough, yellowish-brown or ± reddened, dark-brown later on. With many long spines, up to 3 (5) mm. Galls on shoots, especially conspicuous at the ends and multi-chambered; with smaller sized galls also on all leaf parts, flowers and hips. Containing a single larva per chamber. Rosa spp.: Diplolepis mayri

13c Galls similar to those of D. mayri, but only in their external morphology, especially when the galls of the last species develop on hips. However, D. fructuum galls are produced by the hypertrophy of seeds inside the fruit, the development of which can finally split the external envelope of the hip. In this case, each seed is modified into an egg-shaped multilocular gall, containing up to 10 larval cells and reaching a size of 15 x 12 mm; one hip can be modified into a large multilocular gall. Galls of D. mayri do not split the external envelope of the fruit. R. canina: Diplolepis fructuum

13d Rounded or elongate swelling in stem, smooth when young, later becoming fissured; containing several orange or orange-yellow larvae in irregular cavities. 6–7; gall splits in 7–8 releasing larvae which pupate in soil. R. spinosissima: Janetiella frankumi

13e Oblong swelling on stem, 80–120 x 20–30 mm, surface slightly fissured. R. gallica: Unidentified microlepidopteran

14a Galls almost exclusively on leaves > 15

14b Shoot axis with acuminate- to oval or elongate spindle-shaped swellings, up to 10 mm long, one- to more-chambered. R. majalis, spinosissima , tomentosa: Diplolepis sp.

15a Galls ± globular, with strongly constricted attachment, only protruding on a single side of leaf => 16

15b Galls on both leaf sides, sometimes coalesced into bumpy groups, surrounded by a ± wide, unchanged leaf margin, variously shaped, rotund or oblong, glabrous or rarely provided with small spines; single galls usually 3–5 mm long, yellow-green, sometimes reddish, one-chambered; on leaf midrib and stalk, ± uneven, more- to one-side, sometimes with several united into larger, almost homogenous gall bodies. On all leaf parts, also on flowers, even on corolla. Containing a single larva. Rosa spp. Diplolepis spinosissimae

16a Outside gall wall glabrous, in some cases tuberculate or provided with short papillae, also with only a few, almost normal spines => 18

16b Galls with many thin or with only a few conspicuous strong and rough spines => 17

17a Galls rotund, 4–6 mm, ± red tinged or spotted, with several strong, sometimes slightly bent, tough spines, star-like; robin’s pincushion. One-chambered, containing a single larva. Aberrant gall form indicates presence of parasites or inquilines. Rosa spp.: Diplolepis nervosa

17b Galls rotund, with many often unequal large slender spines, up to 3 mm long. On leaf-blades or calyx mainly one-chambered; on larger organs often several are united into larger many-chambered, bumpy aggregations. Rosa spp.: Diplolepis mayri

18a Galls glabrous, rarely somewhat tuberculate, up to 8 mm across; one-chambered; thin-walled, mainly on leaf underside, occasionally on upper side and then conspicuously reddened, also on flower peduncles, even on stamens or the tips of calyx leaves or even on attachments of spines, as well as on protuberances of D. rosae galls. Galls containing parasites or inquilines are often variously disfigured and sometimes enlarged and many-chambered. A single larva per chamber. Rosa spp.: Diplolepis eglanteriae

= Periclistus species may be inhabitants of irregularly shaped, also enlarged globular galls of several Diplolepis species. These are commensals developing outside the gall chamber in separate cavities of the gall wall

18b On R. arvensis develops in inconspicuous galls: Diplolepis nervosa

18c Galls similar, but usually provided with short, acute, simple, stiff ± reddened spikes or papillae. Containing a single larva. R. canina, caesia, centifolia, pomifera, etc.: Diplolepis nervosa

19a Leaf blade curled over extensive parts or ± loosely rolled => 23

19b Leaf folded pouch-like, or with pustule-shaped egg capsules or with hair felts => 20

20a Pustule-shaped procecidia (oviposition scars, not true galls) up to 2 mm across => 22

20b Folds or erinea => 21

21a Halves of leaflets narrow pod-like, folded upwards, up to a narrow marginal border strongly swollen, pouch-like; galls sometimes arched, sickle-like. Wall succulent, thickened, brittle, sometimes conspicuously reddened. Containing several orange-yellow larvae. Rosa spp.: Dasineura rosae

21b White to reddish erinea at undefined places. Strongly infected leaflets roll in ± longitudinally upwards. R. rubiginosa: Unidentified gall mite

22a Often with several egg capsules between leaf teeth at leaf margin. Rosa spp.: Arge gracilicornis

= On various occasions also Arge enodis has been reported as producing egg capsules on roses, arranged like strings of pearls. This sawfly normally lives on Salix

22b Pustules, on both sides of leaf, 2–3 mm long, protruding further on upper side, pale yellow to -brown, usually single, usually in petioles, more rarely in basal leaf blade parts, also in stipules. R. canina: Cladardis elongatula

= The female of the sawfly Ardis pallipes deposits her eggs in hardly conspicuous egg capsules in the tips of developing shoots. The thick, yellowish larva up to 10 (12) mm long, eats into pith a 30–40 mm long downwardly directed tunnel, pushing the shoot downwards while it withers.

= Also the sawfly Cladius pectinicornis deposits its eggs in rapidly shrunken procecidia on the petiole surface. Larvae gregarious on leaves, at first eating the parenchyma in between the veins, then producing holes.

23a Leaf blade ± tube-shaped rolled or bent upwards and browned => 25

23b Leaf blades conspicuously curled, variously bent => 24

24a Single or several leaves at stem deflected; their leaflets crumpled, almost nest-like downward converged; at infestation site usually dark green. Containing a single or several froth-covered nymphs. Philaenus spumarius

24b Leaf blades of the terminal leaves curled and ± strongly deflected; usually with several bunched together in loose nests. Rosa spp.: Aphis pomi

25a Leaf blade bent upwards, not thickened; ± discoloured, spotted or browned => 27

25b Rolls of leaf margin => 26

26a Both leaf blade halves tube-shaped rolled downwards to midrib, additionally often twisted. On many wild roses and cultivated forms: Blennocampa phyllocolpa

26b Leaves loosely rolled upwards, hardly thickened, not or slightly discoloured. R. canina: Callyntrotus granulatus

27a On R. alpina, spinosissima: Eriophyes rhodites

27b On R. canina, ? alpina: Callyntrotus schlechtendali

28a Up to 50 (80) mm long, rotund masses with thread-like, ± branched appendages. “Bedeguar”, “Robins pin cushion gall”. Usually many-chambered, very tough, ± reddened. Rosa spp., not on cultivated roses: Diplolepis rosae

28b Stems of R. canina with strong nodular swellings bearing: Viscum album

29a Sori orange-coloured or brownish => 30

29b Shoot tips and expanded parts of ± curved leaf blades covered with a dense, white, or grey mycelium. Rosa spp.: Podosphaera pannosa

30a Young shoot axis, leaf blade, -midrib, stipules, petioles, calyx leaves or young fruits with buckled swellings, their surface eventually covered with orange spore masses. Galls according to response ability of infected substrate. Fungus with all spore forms monoecious => 31

30b Leaves often completely infected, on underside with rotund, often coalescing, dusty, brownish sori of (1) 2 (3) celled teliospores. Leaf blades stay smaller and remarkably thickened. R. acicularis, macrophylla, majalis and relatives: Phragmidium kamtschatkae

31a Aeciospores with loosely arranged spines; wall thickenings of germ pores not substantially protruding inwards => 32

31b Aeciospores with densely arranged, coarse spiny warts; provided with 6–8 germ pores, with wall thickenings protruding hemispherically inwards. Rosa spp.: Phragmidium tuberculatum

32a On R. alpina, majalis and spinosissima. Fungi differ from next species insignificantly and mainly biologically => 33

32b On many other Rosa species as well as on cultivated forms. Teliospores 5–9 celled, often upper half broadened; slightly narrowed at apex, with short papilla. Galls like those of previous species. Rosa spp.: Phragmidium mucronatum

= Mycetophagous gall midge: Mycodiplosis coniophaga

= Almost witches’ broom-like malformations are initiated by unknown causes

33a On R. alpina, acicularis, caesia var. glauca, majalis, pomifera: Phragmidium fusiforme

33b On R. caesia, rubiginosa and many cultivated spp.: Phragmidium tuberculatum

33c On R. majalis, spinosissima, rubrifolia. Teliospores not deep dark-brown as in all previous species, but chestnut-brown: Phragmidium rosae-pimpinellifoliae

gallers on Lathyrus

pub 17.xi.2019

Dichotomous table for gallers on Lathyrus

by Hans Roskam

1a On shoot parts => 4

1b On roots => 2

2a Conspicuous galls => 3

2b Outside of roots not conspicuously changed, giant cells developing inside; at surface temporarily with poppy seed sized egg capsules. Lathyrus spp.: Heterodera sp.

3a Nodular swelling in root body. L. odoratus: Meloidogyne sp.

3b Slender oval to cylindrical galls which grow on roots of very different thickness, apically often branched or hand- to coral-shaped, subdivided, on many hosts, up to 8 mm long and 1.5 mm broad, sometimes united into larger complexes. Lathyrus spp.: Rhizobium leguminosarum

4a On inflorescences, flowers or fruits => 36

4b On vegetative parts => 5

5a Galling confined to leaf blades or buds => 16

5b Galling on other vegetative parts including malformations of terminal shoot => 6

6a Malformations mainly or exclusively confined on stem or axial parts => 13

6b Extensive malformation of complete shoot systems => 7

7a Usually expanded malformations of shoot tips => 9

7b Galls on basal parts => 8

8a At stem base are several close shoots, severely stunted, succulent, thickened, ± curved and bearing minute, crippled small leaves. L. odoratus: Rhodococcus fascians

8b Stem bases of young plants stunted in development, severely stunted and over about 40 mm long, spongy, swollen; petioles and basal veins of infected leaves similarly swollen. L. odoratus: Ditylenchus dipsaci

9a Malformations by animal causers => 11

9b Systemic diseased shoot tips show a stunting of internodes and bear slightly clustered, stunted, pale, at margin ± deflected and relatively thickened leaves, which on their underside, as on the young shoot axis, are covered with a whitish-grey down of conidia => 10

10a On L. palustris, heterophyllus, sylvestris: Peronospora lathyri-palustris

10b On different Lathyrus species:

a On L. linifolius: Peronospora orobi

b On L. niger: Peronospora senneniana

c On L. pratensis, nissolia: Peronospora trifoliorum

= These cecidogenic fungi develop systemic infections, and may induce different responses in different host plants. Any additional assignations of Peronospora forms on different Lathyrus species require further study; additional micro-species have also been described from southern areas

= Furthermore Peronospora viciae, frequent on several Lathyrus species, also on Pisum and Vicia, causes proliferating leaves and buds forming a rosette

11a The margins of ± stunted leaflets of many leaves are rolled => 12

11b Few to several leaves are usually at the one-sided bent axis ± deflected, locally deep green and are nest-like converging. Lathyrus spp.: Philaenus spumarius

12a Leaflets mainly of the terminal leaves with narrow, hardly discoloured upward rolled margins. L. pratensis, sylvestris: Aculops lathyri

12b The stunted leaflets usually of all leaves on the strongly necrotic plant are loosely rolled upwards, yellow-green, not thickened. L. pratensis: Odontothrips loti and/ or O. phaleratus

= Stunting of various parts are occasionally caused by the black-brown “pea thrips” Kakothrips robustus

13a Shoot axis with localised spindle-shaped or semi-globular galls => 14

13b Wart-shaped, green galls on stems, usually coalescing into broadened crusts. L. niger: Synchytrium viride

14a Bulges caused by fungi with distinct fruiting bodies on the outsides => 15

14b Stem with swelling on all sides, spindle-shaped, up to 10 mm long with central chamber. L. annuus, cicera, etc.: Holotrichapion gracilicolle

= The larva of Cyanapion columbinum lives in elongated one-sided stem galls and pod-like galls on leaves of L. heterophyllus

15a More or less semiglobular or oval galls, 3 x 10 mm long, many occurring on upper stem parts, inflorescence stalk as well as in petioles. L. linifolius, pratensis: Physoderma lathyri

15b The aecia bearing mycelium may develop facultatively spindle-shaped, slightly swollen sori on responsive stem parts or petioles. Aecia small, depressed, with yellowish, broadly deflected, with lacerate margins usually in loose groups on leaf spots. Lathyrus spp.: Uromyces viciae-fabae

16a Galls induced on single leaves or their parts => 19

16b Several leaves involved in the development of a ± bud-like or onion-like swollen single gall => 17

17a Malformations of shoot tip => 18

17b Rough swelling of bud in leaf axil. Containing a single larva. L. pratensis: Cyanapion alcyoneum

18a The stipules enclose a mass of disfigured leaves or inflorescence buds, resulting in a ± globular gall at the shoot tip; internodes of terminal shoot partly shortened. Larvae gregarious, yellowish-white. L. pratensis: Contarinia jaapi

18b Inflorescence transformed into a rotund structure bearing many, ± largely stunted buds; these completely reduced and ± greened. Gregarious white larvae. L. pratensis, ? clymenum: Dasineura pratensis

18c Two terminal stipules slightly swollen at base and ± discoloured and enveloping a mass of dying tissues. Terminal shoot stops further growth and dies. Usually complete plant ± dwindling and non-flowering. Larvae gregarious, from white to pale red. L. pratensis, ? sylvestris, ? tuberosus, ? vernus: Dasineura lathyricola

= Yellow larvae of Dasineura lathyrina develop as inquilines in galls caused by D. lathyricola

= Several unidentified gall midges have been recorded on tips of side- and terminal ± onion-like swollen shoots. Leaflets ± strongly enlarged, fleshy thickened, brittle, ± leather-like folded upwards. Larva whitish or also orange-coloured. Because of the different colour of larvae several midge species are probably involved.

19a Malformation of leaves and buds caused by a false mildew, forming a rosette and causing further distortions => 10

19b Malformations of leaf blade or petiole => 20

20a Malformations of leaf blade => 21

20b Petiole with weak spindle-shaped swelling. L. vernus: Apion sp.

21a Marginal roll or pod-like fold of leaf => 23

21b Curling of leaf or locally defined galls on unfolded leaf blade => 22

22a More or less rotund to oval galls on leaf blade. L. linifolius: Physoderma lathyri

= Enations on leaves of Lathyrus species are often caused by viruses.

22b Leaf curls associated with other malformations. Unidentified aphid

23a Loose to compact, even cartilaginous marginal rolls or also folds caused by midge larvae => 24

23b Leaf margin over variable length irregularly rolled, occasionally up to midrib. The gall wall is variously thickened and appears to be ± hard, sometimes brittle and yellowish spotted. L. sylvestris, also L. cicera, heterophyllus, latifolius, pratensis, tuberosus: Cyanapion columbinum

23c Leaflets mainly of the terminal leaves with narrow, hardly discoloured upward rolled margins. L. pratensis, sylvestris: Aculops lathyri

24a Galls on different Lathyrus species => 28

24b Galls on L. pratensis (records on different Lathyrus species are marked with ‘?’ need verification) => 25

25a Leaflets or stipules with rolled margins => 26

25b Leaflet or stipule swollen and folded over midrib, forming a soft discoloured pod ± mussle-shaped. L. pratensis: Dasineura lathyri

26a Marginal roll usually on one side, not involving the whole margin => 27

26b Marginal roll often enlarged, violet discoloured, rolled upwards over midrib on both sides. Originally described as looking like a cowry shell. Reddish larvae. On L. ? pratensis, sylvestris: Anabremia bellevoyei

27a The not thickened, soft and hardly discoloured leaflets are ± tightly rolled upwards. Larvae yellowish white at first, later pale red: Jaapiella volvens

27b Marginal roll hardly thickened and not discoloured, one or both margins rolled inwards. Usually in the topmost parts of the plant ± dwindling and non-flowering. Larvae gregarious, from white to pale red. L. pratensis, ? sylvestris, ? tuberosus, ? vernus: Dasineura lathyricola

28a Galls on different species of Lathyrus (not on L. linifolius) => 29

28b On L. linifolius, ? sylvestris. Tube-shaped to cylindrical, not thickened and discoloured, sometimes ± reddened roll containing white to pink coloured larvae: Lathyromyza schlechtendali

29a Galls on L. vernus => 30

29b Galls on L. palustris and L. sylvestris group, including L. heterophyllus, latifolius, odoratus, tuberosus => 31

30a Cartilaginous roll on leaflets and stipules. Larvae yellowish. Macrolabis orobi

30b On leaflets and also stipules the roll, often of only a part of the margin and usually apically situated, does not reach the basal part of median vein: Unidentified gall midge

31a The upwardly bent parts are fleshy to cartilaginously thickened => 33

31b Leaflets or also stipules weakly enlarged, softly rolled upwards => 32

32a The not thickened, soft and hardly discoloured leaflets rolled upwards on L. sylvestris. Larvae whitish: Unidentified gall midge

32b On leaflets and also stipules the roll, often of only a part of the margin and usually apically situated, does not reach the basal part of median vein, contain whitish larvae. L. tuberosus: Unidentified gall midge

32c Roll on leaflets, often of only a part of the margin, does not reach the basal part of median vein. Containing pale orange larvae. L. palustris, vernus: Macrolabis orobi

33a Galls on L. pannonicus and L. tuberosus => 34

33b Galls on L. heterophyllus and L. sylvestris => 35

34a Tube-shaped, strongly enlarged, especially at base, pale green rolling together of ± shortened appearing leaflets. Containing white larvae. L. pannonicus, tuberosus: Various unidentified gall midges

34b More or less unexpanded leaflets are folded upwards. Gall wall strongly thickened, cartilaginous brittle, pale green, sometimes margined by narrow normal leaf blade parts. Containing several larvae. Unidentified gall midge

35a Leaflets or stipules often enlarged, violet discoloured, rolled upwards over midrib on both sides. Reddish larvae. L. sylvestris, ? pratensis: Anabremia bellevoyei

35b Similar gall with fleshy leaf rolls. Reddish larvae, pupation in galls. L. heterophyllus, sylvestris: Geocrypta heterophylli

36a On fruits => 43

36b On inflorescences or flower buds => 37

37a Galls on single flower buds => 39

37b Malformation of inflorescence => 38

38a Inflorescence transformed into a rotund structure bearing many, ± largely stunted buds; these completely reduced and ± greened. Larvae white. L. pratensis, ? clymenum: Dasineura pratensis

38b Already the young inflorescence is severely stunted. Several larvae between flowers. L. tuberosus: Unidentified gall midge

= From L. tuberosus malformations have been assigned to a Contarinia sp.

39a Flower buds swollen, unopened, on several Lathyrus species, but not on those mentioned in lead 39b. Various unidentified gall midges

= Similar galls occur on L. niger with yellow, jumping larvae, as well as on L. vernus with such jumping but cream-coloured larva

39b Flower buds swollen, unopened on L. linifolius, pratensis, tuberosus, odoratus, sylvestris => 40

40a Galls on L. odoratus, sylvestris, tuberosus => 42

40b Galls on L. pratensis and linifolius => 41

41a Flower buds swollen, unopened. Larvae white to lemon-yellow, jumping. L. pratensis: Contarinia lathyri

41b On L. linifolius. Flower buds slightly swollen, unopened. Containing a single white to pink-coloured or reddish larva. Also on L.? sylvestris, ? pratensis,? tuberosus, ? odoratus: Lathyromyza florum

41c Same host, flower galls with yellowish-white, jumping larvae. Unidentified gall midge

42a lower buds slightly swollen, unopened. Larvae vitreous to milk-white, or reddish (after description) non-jumping. L. sylvestris: Dasineura silvestris

42b Similar galls contain a single white to pink-coloured or reddish larva. On L. linifolius, also on L. ? sylvestris,? pratensis, ? tuberosus, ? odoratus: Lathyromyza florum

42c Similar galls contain red, non-jumping larvae. L. sylvestris: Dasineura fairmairei

43a Malformations on fruits caused by insect larvae => 44

43b Malformations on fruits caused by fungi. Fruits by early infestation stunted in further development, only occasionally slightly disfigured. Later on with dusting of dirty brown-violet spores; mycelium destroys only in case of early, externally usually indistinct infestation of all seeds of a pod. Lathyrus (Orobus) species: Thecaphora lathyri

44a Malformations caused by gall midge larvae => 45

44b Beetle larvae feed within the pod on the developing seeds; this may cause some galling of the pods. L. linifolius, pratensis, sylvestris, vernus: Tychius quinquepunctatus

45a Pod bulging. swollen, discoloured. Malformations without fungus inside. Many white to lemon-yellow larvae inside, able to jump. L. sylvester, tuberosus: Contarinia silvestris

45b Local, oval or ± spindle-shaped swellings, inside covered with a dense mycelium. Containing a yellow to orange-yellow midge larva: Asphondylia lathyri

gallers on Carex

pub 16.xi.2019

Dichotomous table for gallers on Carex

by Hans Roskam

1a On above-ground parts => 2

1b Roots with terminal swellings, 5–8 mm long, club-shaped; with almost colourless elliptical spores inside. C. limosa: Entorrhiza caricicola

2a In flowers or fruits => 17

2b On vegetative parts => 3

3a Leaves or stems with malformations caused by rusts or smuts => 14

3b Malformations caused by animals => 4

4a On leaves => 12

4b On buds, shoot tips or stems => 5

5a On stems or rhizomes => 7

5b On buds or shoots => 6

6a Lower parts of side shoots swollen, bud-like. C. praecox, ? echinata, ? flacca: Planetella sp.

6b Buds stunted, thickened; galls corniculate. C. elata, flacca, montana, pallescens, nigra, praecox, sylvatica. Planetella cornifex

7a Stem with various kinds of swellings => 9

7b Stem with lateral tufts of leaves or with depressions => 8

8a The stem with a laterally protruding severely stunted shoot with a tuft of severely disfigured, yellowish leaves, the covering sheaths are especially well developed and broadened. Carex sp., muricata, etc.: Livia crefeldensis

8b Stem and leaf sheath with weak depressions. Larvae often many per culm. Each depression contains a single orange-red larva. C. appropinquata, ericetorum, echinata, muricata, remota: Thurauia aquatica

8c With similar biology, may be conspecific with the previous midge. Thurauia uliginosa

= Also other gall midge larvae develop underneath the leaf sheaths of sedges without causing distinct galls:

a Antichiridium caricis, larvae red, on C. echinata

b Antichiridium striatum, larvae yellow, on C. pseudocyperus and Molinia caerulea

c Brachydiplosis caricum, on Carex spp.

d Sterrhaulus corneolus, larvae yellow-red, on Carex spp. According to Jaap (1918) this species also develops as an inquiline in galls of Planetella gallarum

9a Galls egg-shaped, rotund- to oblong-oval => 10

9b Axis of shoot thickened at base, onion-like. Sometimes the complete axis is transformed into a horn-like gall. C. ? bigelowii, flacca, montana, nigra, praecox: cf. Planetella cornifex

10a Galls one-chambered, usually not in dense clusters => 11

10b Shoot axis on rhizome already seriously stunted; often with only etiolated leaves above the ground. Stems or leaf sheaths with ± egg-shaped galls, which usually consist of several oblong-oval, flattened one-chambered parts. C. acuta, acutiformis, arenaria, davalliana, hirta, muricata, nigra, ? praecox: Planetella arenariae

10c Similar galls on C. flacca, nigra, praecox: Unidentified gall midge

11a Stem of shoot in ground, close to surface, with one-chambered, egg-shaped brown swelling, up to 2.5 mm long and 1.5 mm wide, grain-like. C. divulsa, echinata, nigra, praecox, pallescens, ? elata, filiformis: Planetella granifex

11b Similar, often acuminate galls, which are often only attached to the leaf at the tip and are ± distant from the further part of the leaf that bears them. Containing single larvae. Carex spp.: Planetella caricis

11c Similar galls, about 5 mm long. C. praecox: Planetella sp.

11d From C-Eu has been described from C. praecox: Planetella caricis var. baudysi

11e Acuminate galls on culms close to the ground; egg-shaped, about 2 mm long and 1.2 mm wide, one-chambered. C. echinata: Planetella kneuckeri

11f Stem of shoot, also leaves, usually close to the ground, with oblong, glabrous, ± glossy brown, terminally rounded galls, only connected with their middle part to the basal leaf part, narrowed at both ends. Containing a single white larva. Carex spp.: Planetella gallarum

11g Similar galls on C. vesicaria. Larvae white: Planetella tarda

11h Similar galls on C. pseudocyperus: Unidentified gall midge

12a Galls usually less than 5 mm, one-chambered => 13

12b At base where leaves come close to one another, are complexes of several whitish or brownish galls, 5–8 mm long and 2–3 mm thick, acuminate, with thin leathery walls. Containing a single larva. C. ? hirta, pilosa, rostrata, vesicaria, and probably other sedges. Planetella fischeri

12c Similar galls at base of a leaf at lowest node. C. acuta, nigra, praecox:
Planetella rosenhaueri

12d Similar galls on C. davalliana, filiformis, vesicaria: Planetella sp.

= On C. davalliana: Planetella billoti

12e Single- or multi-chambered gall, up to 10 mm long and 5 mm broad. C. appropinquata, acutiformis: Planetella sp.

12f Oblong swellings at leaf base. C. nigra, praecox, pallescens, elata, ? filiformis: Planetella sp.

12g Similar galls on C. divulsa, pallescens: Planetella frireni

13a Subterranean leaf sheaths with oblong-oval single-chambered swellings, up to 4 mm long, about 1 mm broad, thick-walled, dark-brown. Containing a single orange-yellow larva. C. flacca: Planetella sp.

13b Small blister-like swellings of leaf base; often many on several shortened leaf blades. C. acuta, ? hostiana, elata, etc.: Planetella tuberifica

13c Leaves similarly swollen at base, containing many slender spindle-shaped single galls. Each chamber contains a single larva. C. acutiformis, pseudocyperus: Planetella tumorifica

13d Rotund-oval galls, about 3 x 2 mm on subterranean leaf parts. C. divulsa, praecox: Planetella subterranea

14a Expanded stripes on leaves, caused by smut fungi => 15

14b Patches in disfigured stalks of inflorescence; midrib and also culm of diseased plants ± shortened. Spores in balls, not enveloped by sterile cells. Carex spp.: Moreaua aterrima

15a Spores clustered in balls, enveloped by sterile cells => 16

15b Spores single. Smut sori in long, parallel stripes. C. brunnescens, canescens, glareosa, lachenalii, macloviana, etc.: Orphanomyces arcticus

16a Stripes of smut on leaves of various length. Spores 1–2 (4) often without gaps, enveloped by sterile auxiliary cells. Carex spp.: Urocystis fischeri

16b Stripes similar. Spores with 1–6, mainly 3, ± completely enveloped by sterile auxiliary cells. C. montana: Urocystis littoralis

17a Malformations on flowers or fruits, caused by fungi => 22

17b Galls on flower parts caused by gall mites or gall midges => 18

18a Malformations on ovaries or fruits caused by gall midge larvae => 19

18b Utricles transformed into very long, thickened galls. C. misera, nigra, praecox: Phytoptus caricis

19a Galls less than 5 mm long => 21

19b Galls about 5–9 (12) mm long => 20

20a Ovary transformed into an acuminated, cylindrical, usually pale green gall, 5–10 (12) mm long. Larva orange. Especially on sedges of the subgenus Vignea, such as C. brizoides, caryophyllea, disticha, divulsa, vulpina, pairaei, etc.: Wachtliella caricis

20b Galls similar, more club-shaped. Larvae pink-coloured. C. arenaria: Oligotrophus loewianus

20c Utricles strongly enlarged, containing a single lemon-yellow larva. C. cuprina: Dasineura inflata

= The galls cannot be differentiated externally form those of Wachtliella caricis. A difference is that the larvae of inflata are lemon yellow, while those of caricis are orange

21a Ovary, or fruit inflated into an egg-shaped gall, up to 3 mm long. Containing a single orange-coloured larva. C. elata: Unidentified gall midge

21b Similar gall, described in no more detail, on many other sedges. Unidentified gall midge

21c Utricles thickened, containing a single orange-red larva. C. acutiformis:
Dasineura koesterbecki

21d Utricles disfigured, containing a single orange-red larva. C. paniculata:
Dasineura minungula

22a On the first slightly enlarged ovaries, which are soon destroyed, develop considerable smut bodies, protruding conspicuously from the inflorescence; these are initially compact and enclosed by a white envelope, releasing their solitary, mutually ± firmly clotted spores rather late => 24

22b Malformations on various flower parts or on ovaries with lightly dusting of sori => 23

23a Ovaries swollen, soon filled with a dark olive-brown to blackish mass of single spores, pervaded by sterile hyphae. Spores lightly dusting or crumbling, leaving the sterile hyphae as characteristic, soon ± fraying bundle. C. riparia and many other Carex species: Farysia thuemenii

23b Black-brown spore balls in various disfigured flower parts; on more rarely infected female florets often in the abnormally elongated perigyne, often only in the ovary, on male florets predominantly in the anthers. Carex spp.: Moreaua aterrima

24a Spore wall glabrous or with small papillae => 27

24b Spore surface with distinct warts => 25

25a On C. canescens, nigra, rostrata => 26

25b On many sedges of the sect. vesicariae, hirtae and hybrids: Anthracoidea subinclusa

26a On C. rostrata, pilulifera, rotundata and close relatives: Anthracoidea inclusa

= On C. canescens, with glabrous spores, lives the closely related Anthracoidea karii

26b On Carex sect. Acutae: Anthracoidea echinospora

26c On C. canescens and relatives: Cintractia fischeri

= On C. pilulifera, the ovary smut Cintractia caricis-oederi has been described.

27a On many sedges species complexes of ovary smuts occur. Spores irregular, ± edged, 15–26 x 12–22 µm. Wall dark brown, with very many fine warts. Nominate form on C. pilulifera: Anthracoidea caricis

27b Many fungi are ± host-specific and partially morphologically distinct:

a On C. alba. Spores ± angular, with many fine papillae, 19–27 x 12–21 µm. Also recorded from C. digitata, ornithopoda, sempervirens: Anthracoidea caricis-albae

b On C. arenaria. Spores dispersing early, rotund to elliptical, ± flattened, 13–18 x 12–16 µm.: Anthracoidea arenariae

c On C. brizoides, cespitosa, divulsa, echinata, muricata, leersii, pairae and relatives Spores irregular rotund, appearing almost glabrous at maturity, 13–20 x 12–17 µm.: Cintractia leioderma

d On C. brunnescens and hybrids. Spores 15–22 x 10–16 µm, ± irregular rotund-elliptical, with yellowish-brown glabrous or minutely punctated membrane; therefore clearly different from Anthracoidea fischeri: Anthracoidea karii

e On C. chordorrhiza. Spores rotund to elliptical, 15–22 x 11–19 µm; wall dark-brown, with, only slightly protruding, about equal warts; forms transition to warty-spored species. Usually all spikes with many or all ovaries diseased: Anthracoidea aspera

f On C. digitata and relatives. Spores ± elliptical, very polymorphic, 18–27 x 13–22 µm. Wall brown, with many densely positioned, not protruding, rotund or ± elongate small warts. Smut grains rotund, 2–5 mm across; usually solitary to several in the fruiting spikes, sometimes dropping as a whole: Anthracoidea irregularis

g On C. dioica and hybrids. Spores rotund-elliptical, ± angular, 18–26 x 16–22 µm. Wall dark brown, with densely arranged inclusions, making the membrane almost non-transparent. Close to nominate form: Anthracoidea turfosa

= Also found on C. dioica, distinguished by its smaller spores is Anthracoidea caricis-dioicae

h On C. ferruginea: Anthracoidea caricis

i On C. flacca, buxbaumii. Smut grains relatively soft and soon dusty; spores rotund or elliptical, sometimes slightly angular, 16–26 x 14–22 µm.: Anthracoidea pratensis

k On C. glareosa. Spores 15–21 x 13–19 µm; membrane very thick, up to 2.6 µm, with densely arranged ± coalescing, minute papillae: Cintractia glareosa

l On C. hirta. Spores rotund- to oblong-oval, usually strongly flattened and irregular angular, 16–26 x 13–21 µm; wall dark-brown, up to 2 µm thick, almost glabrous: Cintractia angulata

m On C. limosa and relatives. Spores rotund to elliptical, often flattened, 17–26 x 14–24 µm; wall almost glabrous. Smut grains 2–5 mm across; envelope soon rupturing; spores crumbling: Anthracoidea limosa

o On C. panicea and relatives. Spores rotund- to oblong-oval, very irregularly shaped and rimmed, densely finely punctate, 18–20 x 13–17 µm. Other hosts are C. echinata, nigra, praecox, pilulifera: Cintractia baccata

gallers on Prunus

pub 16.xi.2019

Dichotomous table for gallers on Prunus

by Hans Roskam

1a On above-ground parts => 3

1b On roots or root collar => 2

2a Roots with small elongated or nodule-shaped swellings. P. domestica, persica: cf. Meloidogyne hapla

2b Pea-, walnut- up to even fist-size proliferations on root collar, also on basal root- or stem parts. P. amygdalus, armeniaca, avium, cerasifera, domestica, insititia, mahaleb, persica: Agrobacterium tumefaciens

3a On flowers or fruits => 52

3b On vegetative parts => 4

4a Malformations not bush- or broom-like => 7

4b Conspicuous witches’ brooms or mistletoe gall => 5

5a Witches’ brooms => 6

5b Upper stem parts or older branches with spindle-, club-, or nodule-shaped swellings bearing: Viscum album

6a Conspicuous, occasionally even up to 3 m large, perennial witches’ brooms. Basal part of twigs distinctly swollen, deflected downwards and then growing steeply erect. Leaves variously swollen, bladder-like, leaf blades hardly thickened; on underside usually covered with a grey-white pubescence of asci when the fungus has matured. On P. avium, less frequent on P. cerasus, fruticosa, and some close foreign cherries: Taphrina wiesneri

6b Similar, usually less substantial, only exceptionally up to 1 m large, perennial witches’ brooms on P. cerasifera, domestica, insititia, spinosa, ussuriensis: Taphrina pruni

= Witches’ brooms also occur occasionally on species belonging to the subgen. Euprunus, especially on P. spinosa, without verified causers

6c On P. armeniaca: Taphrina armeniacae

= Taphrina insititiae is also able to cause witches’ brooms on Prunus species. The mycelium develops intercellularly in the branches and leaves

7a On shoot ends, buds or on leaves => 16

7b On younger or older shoot axis => 8

8a On green shoots or thin twigs => 10

8b On stronger stem parts => 9

9a Bark with localised thickenings, cancer-like proliferations and exuding gum. Prunus spp.: Enarmonia formosana

= From similar cancer-like bark necrosis has also been described the sac fungus Phomopsis prunorum

= Cancers on P. avium are also caused by viruses.

9b Closed, or later on opening, variously shaped Nectria cancers, which often result in stronger bending of younger stems, sometimes occurring on older stems in large numbers. P. serotina: Neonectria ditissima

9c Smooth bark of variously aged stems with small irregular rimmed depressions, which contain a scale, up to 1.6 mm long. P. avium, domestica, dulcis, persica: Epidiaspis leperii

9d Woolly apple aphid on cancers of stem and branches. P. domestica: Eriosoma lanigerum

10a On annual, still green shoots => 12

10b On thin, wooden, two- to a few years old twigs => 11

11a Rotund galls, up to about 2 mm long, at first green, then often dark-red, eventually ± browned, single or usually clustered on veins of bud scales or leaves of 2 years old shoots. P. amygdalus, domestica, insititia, armeniaca: Acalitus phloeocoptes

11b Similar galls on P. spinosa: Acalitus prunispinosae

11c Single or several globular to irregular oblong proliferations, mainly one-sided with cracked or rugose, often gum covered surface; on two- to a few years old twigs. P. armeniaca, persica: Stigmina carpophila

11d Rotund to spindle-shaped swelling often at base of side stems. Inside is a yellow lepidopteran caterpillar with contrasting head. P. padus: Argyresthia semifusca

12a Stem with cup-shaped, nodular or bulge-like malformations > 13

12b Shoot tip covered by dense, white mycelium, variously extending to leaves. P. persica: Podosphaera pannosa

13a Malformations smaller than 5 mm => 14

13b Malformations larger than 5 mm, elongate spindle-shaped swellings => 15

14a Green axis with small, almost cup-shaped protuberances. P. padus, avium, communis, domestica, dulcis, mahaleb, spinosa: Phyllocoptes eupadi

14b Small nodular protuberances, often with several along the axis. Prunus spp.: Stephanitis pyri

15a Extensive swellings, up to 35 mm long and 7 mm wide, yellow-green, mainly one-sided, ± curved bulge-like on P. padus: Taphrina padi

15b On P. domestica, spinosa. Similar but smaller swellings of axial parts: Taphrina pruni

15c Similar malformations on twigs of P. persica: Taphrina deformans

16a On shoot tips or leaves => 18

16b On buds of woody or almost woody young shoots => 17

17a Bud transformed into a 4–5 mm long, acute, rotund or egg-shaped, thin-walled greenish, eventually browned gall, surrounded at base by several scales. Inner wall lined with mycelium. Containing a whitish, later on yellow-red larva. P. cerasifera, domestica, fruticosa, insititia, spinosa and relatives: Asphondylia pruniperda

17b Abnormal multiplication of buds; flowers and fruits do not develop. Attacks result in the death of trees. P. dulcis, persica: Odinadiplosis amygdali

17c Discoloured swellings of stunted shoot buds up to 15 mm long. P. padus: “Anthonomus bicinctus”

17d Bud, with involvement of neighbouring stem parts, strongly swollen; galls inside fleshy. P. padus: Taphrina padi

17e Similar malformations of buds. P. spinosa: Taphrina pruni

17f Similar malformations of buds. P. fruticosa: Taphrina wiesneri

17g Malformation of buds and leaves, caused by gall mites. P. armeniaca, cerasifera, persica: Eriophyes armeniacus

18a Local; or extensive malformations on single leaves or also on many, mainly terminal leaves => 21

18b Galls on shoot tips => 19

19a Axis shortened, leaves bunched together, rolled, uneven, ± rugose and cartilaginous => 20

19b Young leaves folded as in the buds, weakly swollen and pale-green. Galls at base sometimes partially bent outwards. Containing several white larvae. P. spinosa: Unidentified gall midge

20a On P. armeniaca, avium, cerasifera, domestica, fruticosa, insititia, spinosa: Dasineura tortrix

20b White larvae develop as inquilines in same galls. P. domestica, insititia, spinosa: Dasineura sodalis

21a Various malformations caused by aphids => 39

21b Different malformations caused by other causers => 22

22a Leaf blade ± browned or curled and curved inwards, caused by mites, spittlebugs or fungi => 36

22b Leaf blade with expanded marginal rolls, folded over, pouch-like, formation of hairs or small localised protuberances => 23

23a Leaf blade with pouch-like folds or with abnormal pubescence, or localised protuberances => 26

23b Leaf margin rolled or folded over => 24

24a More or less rugose and discoloured upward roll of leaf margin => 25

24b Leaf margin largely deflected downwards. Malformation ± sickle-shaped, at first green, then discoloured yellowish. P. domestica, spinosa: Pristiphora monogyniae

25a On P. armeniaca, avium, cerasifera, domestica, fruticosa, insititia, spinosa: Dasineura tortrix

25b In similar roll of leaf margin on same host larvae of the probably inquilinous: Dasineura sodalis

26a Leaf blade with abnormal pubescence or localised protuberances => 27

26b Border of leaf blade, or leaf blade at midrib or side vein with pouch-like, downward fold. Folds (10) 20–30 (50) mm long, thickened, cartilaginous, often reddened. Eventually with narrow, opening longitudinal slit on upper side. Usually containing several orange-yellow or -red larvae. P. domestica, fruticosa, insititia, spinosa, etc.: Putoniella pruni

27a Pouch-, horn-shaped or nodular galls, or small protuberances or warts => 32

27b Leaf blade with abnormal pubescence caused by gall mites => 28

28a Erinea situated along venation or in vein axils => 30

28b Felt pubescence mainly situated freely on the leaf blade => 29

29a On P. padus, mainly on underside of leaf blade, irregular, at first grey-white, then rust-brown, erinea. Hairs short, thick, club-shaped or irregular: Eriophyes distinguendus

29b Abnormal pubescence on underside of leaves of P. amygdalus, persica: Unidentified gall mite

= Whitish erinea on underside of leaf blade base are caused by Eriophyes similis, normally living in marginal pouch galls

30a Erinea mostly in vein axils, variously extending onto the leaf blade => 31

30b Felt-like pubescence along the veins. Hairs resembling the normal ones. P. insititia, spinosa: Unidentified gall mite

31a Vein axil with upward protuberances; abnormal pubescence on underside. P. spinosa: Unidentified gall mite

31b Small pustules on leaf blade. P. spinosa: Unidentified gall mite

31c Brown tufts of hairs in the vein axils on underside. P. padus: Unidentified gall mite

= The polyphagous thrips Taeniothrips inconsequens, especially frequent on fruit trees, causes small, yellowish, glabrous archings in the vein axils of P. padus

32a Galls pouch-, horn-shaped or globular, caused by gall mites => 34

32b Leaf blade with small upward protuberances or with warts on underside => 33

33a Leaf blade with small protuberances on upper side, with corresponding small depressions on underside, containing flat froth-covered nymphs. P. padus: Psylla sp.

33b Leaf blades on underside with multicellular warts, up to 1 mm across, golden-yellow; also occurring on basal petioles or stems of saplings. P. spinosa: Synchytrium aureum

34a Galls mainly situated in the middle part of the leaf blade or in the vein axils, normally protruding from upperside => 35

34b Elongated oval galls up to 2 mm across, pouch-shaped mainly at margin of leaf blade, protruding strongly on underside and closed, with a weakly pubescent, bulging rimmed slit on upperside. Galls sometimes inversely situated. Of various shape, depending on the substrate, exceptionally also occurring on petioles, on young stems and even on young fruits. P. armeniaca, domestica, fruticosa, insititia: Eriophyes similis

34c Similar galls in P. spinosa: Acalitus prunispinosae

34d Hairy galls on upperside of leaf along the midrib and the veins, on the underside a small opening. P. cerasus, domestica, mahaleb, padus, spinosa: Eriophyes homophyllus

35a Gall horn-shaped on upperside, up to about 4 mm long, with exit hole on underside. Exceptionally also occurring on underside, on petiole or on young stems. P. padus: Phyllocoptes eupadi

35b Rotund or club-shaped pouch galls, up to 2 mm long and 3 mm high with exit hole on underside. Occasionally in vein axils. Exceptionally also on petioles or on young stems. P. domestica, fruticosa, insititia, spinosa: Eriophyes prunianus

= The eriophyoid mite Eriophyes similisprunianus causes protruding pouch- or finger-like galls on the lower surface with a pilose opening on the upper surface of the leaf blade of P. domestica, cerasifera

= Leaves of P. avium, cerasus may have tubercular- to leaf-like proliferations “enations” between the veins. Leaves often rosette-like bunched together or developing as terminal leaf tufts. Leaf blades narrowed, reduced, ± thickened, chequered mosaic-like or mottled, disfigured at margins. Recorded as virus diseases, partly also on cherry and related Prunus species

= Also a “pock disease” is induced by a virus on P. domestica.

36a Leaf blade conspicuously undulately curled or swollen, bladder-like sometimes strongly curved => 37

36b Leaf blades ± converging upwards, markedly stunted, initially mottled yellow, then browned. Mites free-living mainly on the upperside. P. armeniaca, avium, cerasifera, cerasus, domestica, mahaleb, padus, persica, triloba, etc.: Aculus fockeui

37a Conspicuous curls or ± accentuated bladder-like swellings caused by fungi => 38

37b Terminal leaves of young shoots loosely rolled inwards or strongly deflected and twisted over their tops, densely crumpled at infestation site and often deep-green. Containing a froth-covered nymph. P. avium, cerasus, domestica, padus, etc.: Philaenus spumarius

38a Usually expanded parts of leaf blades swollen, bladder-like, curled, curved or ± twisted. Swellings pale green or often intense red, with fleshy thickened, brittle tissue. Stem sometimes stunted resulting in bushy aggregations of leaves. At maturity covered mainly on underside with whitish asci. P. persica: Taphrina deformans

38b Mainly in southern areas, also in GB, occur less conspicuous fleshy curls also on almond, P. amygdalus: Taphrina deformans

38c Conspicuous bladder-like galls on leaves of P. serotina; also the inflorescences may be heavily infested. Introduced from the Nearctic together with its host plant: Taphrina farlowii

38d Several leaves of developing buds are soon completely or partially ± swollen, bladder-like. Diseased leaf parts are hardly thickened, often lighter green than the healthy ones, occasionally reddened at margins. Characteristic symptoms, especially on partially infected leaves. Often on young long shoots all leaves are diseased; stems are ± elongated and thickened. At maturity of fungus the asci develop mainly on underside as an ash-grey covering. P. avium, cerasus, fruticosa: Taphrina wiesneri

38e Similar malformations lacking a reddening of diseased leaf blades. P. domestica, insititia, spinosa: Taphrina pruni

= Red midge larvae developing inside dry fruits of P. domestica containing the fungus Polystigma rubrum belong to the gall midge Dichodiplosis langeni

39a Malformation of single to several leaves on young shoots, which are not conspicuously stunted in development => 44

39b Malformation of many terminal leaves on shoots which are stunted in longitudinal growth => 40

40a Loose clusters at shoot tips => 41

40b Leaves on shoot tip often bunched together in large clusters. Leaf blades strongly curled, ± narrowly rolled inwards. P. avium, sometimes on P. serratula, yedoensis: Myzus cerasi subsp. pruniavium

41a On P. cerasus, spinosa, mahaleb => 42

41b On P. persica strong roll of the not discoloured, curled, sometimes bulging leaves, which are ± densely clustered, nest-like, on the shortened, partially swollen shoot tipL Brachycaudus schwartzi

41c Curled narrow leaf rolls of P. amygdalus, occasionally also of P. persica: Brachycaudus amygdalinus

42a On P. cerasus, spinosa => 43

42b On P. mahaleb. Several, ± stunted and disfigured leaves bunched together in loose clusters at shoot tips: Myzus lythri

43a On P. cerasus. Shoots slightly stunted, leaves weakly deflected, arched: Myzus cerasi

43b On P. spinosa. Leaves strongly curled and shoot tips densely bunched together. Aphids often occurring in masses: Brachycaudus prunicola

= Blackman (2010) furthermore distinguished the aphid Brachycaudus prunifex. Apterae are shiny dark green to black; body length 1.5‒2.4 mm. Colonies occur all-year-round on Prunus spinosa, in spring causing severe leaf curl and discoloration to new growth. There is also a record from P. cerasifera var. atropurpurea. Suggestions of a facultative host alternation to Tragopogon do not appear to be substantiated. Alate males have been collected in 9, but oviparae are not yet recorded. In GB (England, Wales), IRL, and northern F. This species has been synonymised previously with B. prunicola, which occurs on the same host throughout the rest of Eu and in C-As, but it can be distinguished from that species (and from B. schwartzi) by the longer hairs on the antennae and anterior abdominal tergite

44a Leaves with pronounced rolls and curls at margin => 50

44b Leaves only weakly rolled, swollen, bladder-like or slightly curled => 45

45a Aphids not- or only slightly powdered => 47

45b Aphids strongly to densely mealy powdered => 46

46a On P. armeniaca, domestica, insititia, spinosa. Aphid covered with dense mealy layer of wax. Leaves stunted, otherwise only weakly disfigured, slightly deflected, not curled, sometimes discoloured pale-green, occasionally marbled, later on strongly powdered by the exuded aphid wax: Hyalopterus pruni

46b On P. persica, amygdalus. Malformations and aphids similar to those of previous species: Hyalopterus amygdali

46c Aphids on the underside of the leaves, 2‒3 mm long, probably strongly resembling those of Hyalopterus amygdali. P. persica: Hyalopterus persikonus

47a Leaves only weakly swollen or arched, without conspicuous discolouration => 49

47b Leaf blade slightly to conspicuously rolled or arched, ± conspicuously discoloured or yellow spotted => 48

48a On P. padus. Fundatrices pale green; fundatrigeniae dark grey-green: Rhopalosiphum padi

48b Similar malformations causing yellow and red spots on the deflected bladder-like inflated leaves. P. padus: Myzus padellus

48c On P. persica, nana, serotina; variously shaped minor leaf archings or -rolls, which are ± brightened: Myzus persicae

48d Leaves of P. persica are tightly rolled longitudinally: Myzus varians

49a Aphid shining dark red to dark-brown or black. On P. domestica. Leaves slightly deflected, not rolled. Brachycaudus persicae subsp. semisubterraneus

49b Aphid pale green to yellowish green, rather shiny, with three darker green dorsal longitudinal stripes. On P. domestica, fruticosa, insititia, spinosa, mahaleb, ? padus, serotina, etc. Leaves only weakly arched. The apterous aphids inhabit the leaf underside, also the complete shoot: Phorodon humuli

50a On. P. domestica, spinosa and close cherries => 51

50b On P. mahaleb. Leaves in spring with yellowish discoloured, bladder-like-rugose rolls, with walls clearly thickened and ± brittle: Roepkea marchali

51a Aphid 0.9–2.0 mm long, usually pale-green; siphunculi pale, very short, 1/11 to 1/15 times body length. Tip of rostrum not reaching the metacoxae. Leaves narrowly rolled and strongly curled, shoots often ± leaning: Brachycaudus helichrysi

51b Aphid about 2.2 mm long, pale-green with dorsal cuticle sclerotic and often brownish, fundatrices brownish-red. Adults usually with dark pigmented back. Siphunculi mainly brown, 1/6 to 1/8 times body length in fundatrigeniae [viviparous parthenogenetic wingless female aphid produced by a fundatrix and giving rise to further wingless forms or to migrants]. Leaves in spring narrow and curled or rolled, converging, bleaching after departure of aphids. Shoots sometimes ± stunted. P. domestica, spinosa; sometimes P. avium. armeniaca: Brachycaudus cardui

51c Very closely related, and often mixed with foregoing: Brachycaudus cardui subsp. lateralis

52a Malformations on ovaries and fruits => 54

52b Malformations of flowers => 53

52c Abnormal multiplication of buds; flowers and fruits do not develop. Attacks result in the death of trees. P. dulcis, persica: Odinadiplosis amygdali

53a The slightly enlarged corolla remains in bud condition. Receptacle, ovary and base of stamens ± clearly swollen. Larvae jumping, single or several. P. domestica, mahaleb, spinosa: Contarinia pruniflorum

53b Flowers disfigured, unopened. The corolla, which soon dies, arches roof-like over generative parts and receptacle and sometimes regenerating tissue is eaten by yellowish, brown-headed, larvae. P. padus, also mahaleb, avium, etc.: Anthonomus humeralis

53c Flowers disfigured, unopened. P. spinosa: Anthonomus rufus

54a Ovary completely transformed into a tube-like, hollow gall => 56

54b Fruit with localised swellings or ovary galled, including other organs of flower bud or flower => 55

55a Localised pale-green hypertrophies on fruits, also ± reddish discoloured, usually rotund. P. persica: Taphrina deformans

55b Ovaries or young fruits, flowers, flower buds variously disfigured and swollen. P. cerasifera: Taphrina wiesneri

55c Midge larvae develop in fruits of P. cerasus which were damaged by puncture holes of the weevil Anthonomus rectirostris: Lasioptera cerasiphera

= The fruit fly Rhagoletis cerasi has been recorded from from cherries; introduced from N-Am is R. cingulata in fruits of P. serotina.

56a Fruit distinctly enlarged, hollow, at first pale green, then dark coloured. At maturity the fungus is covered with an expanded grey layer of asci. P. cerasifera, domestica, insititia, salicina, serotina, spinosa: Taphrina pruni

56b Ovaries or young fruits transformed into elongate tube-shaped, terminally acuminate, greenish galls, which are black and hollow after sporulating. P. padus: Taphrina padi

56c Similar galls on other hosts belonging to the subgenus Padus: Taphrina confusa

gallers on Achillea

pub 15.xi.2019

Dichotomous table for gallers on Achillea

by Hans Roskam

1a On above-ground or underground shoots => 2

1b Roots with small, more or less spindle-shaped swellings, usually showing lateral roots. A. millefolium: Meloidogyne hapla

2a Malformations of inflorescences, flowers or fruits => 31

2b Malformations of vegetative parts => 3

3a Malformation by animal gall causers of whole plants or extensive parts, shoot tips or terminal buds => 25

3b Galls on stems, including root collar, or malformations of leaves or lateral buds => 4

4a Malformations with distinct sporulating areas on the surface => 22

4b Malformations without sporulating areas => 5

5a Galls on leaves => 12

5b Malformations on shoots, lateral buds or subterranean parts => 6

6a The gall causers are situated within the galls => 7

6b The gall causer is situated within a pit with ± thickened rim; galls usually clustered, causing thickening and distortion of green stems. A. millefolium, setacea: Planchonia arabidis

7a Galls on higher parts of the shoots => 10

7b Malformations on the root collar, subterranean parts of the stem, or on roots => 8

8a Galls oval or spindle-shaped => 9

8b Rotund, 5–8 mm long, thick succulent, one-chambered galls on the root collar or rhizomes; solitary or clustered. One larva per gall. A. millefolium, nobilis, crithmifolia: Oxyna flavipennis

= Larvae and pupae of Campiglossa argyrocephala have been recorded from A. ptarmica, inhabiting axillary buds, and dying stem tips below which rosettes of leaves are further developed, sometimes reminiscent of a gall-like malformation.

9a Closed spindle-shaped galls, with succulent wall; centrally with a chamber up to 12 mm long and 2 mm wide, later brownish-walled. Containing a single larva. A. millefolium, nobilis subsp. neilreichii: Dithryca guttularis

9b Midge gall, ovoid to jar-shaped, up to 6 mm long, initially depending on the location pale or green and soft, later brown, almost black, tough walled, unilocular. At the narrowed upper end with deflected haired lobes around opening when mature. One yellow larva: Rhopalomyia millefolii

10a Lateral swellings at different places on the stem => 11

10b Stem with spindle- or acuminate barrel-shaped swelling, up to 7 (9) mm long swelling, predominantly caused by a proliferation of the pith. Later on a larger area than the galled part is eaten by a caterpillar. Containing a single larva. A. millefolium: Unidentified lepidopteran

11a Stem with node-shaped compact closed proliferations, up to 6 mm long, or galls spindle-shaped, embracing the stem on all-sides over a length of 2–8 mm, lacking distinct chambers. A. millefolium, nobilis, etc.: Subanguina millefolii

11b Galls initially inconspicuous, egg-shaped, up to 2 mm high, unilocular, more noticeable after the emergence of the larvae by a straw-yellow coloration of the surroundings of the emergence hole. Containing a single larva per gall. A. millefolium: Rhopalomyia sp.

12a Leaves bent, curled, also rolled inwards or with little depressions => 18

12b Leaves with wart-, club-, spindle- or ± egg-shaped galls => 13

13a Galls larger than 1 mm => 15

13b Galls smaller than 1 mm, wart-shaped, compound; usually many on the lower leaves, also on stems; sometimes on the additionally deformed parts ± crust- or ridge-like converged => 14

14a Nutritive cells of the warts with golden yellowish content; hence galls yellow. A. ptarmica: Synchytrium aureum

14b Warts pearl-like, initially hyaline, later brownish; content of the nutritive cell colourless. A. millefolium: Synchytrium globosum

15a Galls usually several mm long => 16

15b Galls on both leaf surfaces; rotund oval, about 1–2 mm long, sometimes ± converging; initially whitish or yellowish green, later ± brown, sometimes clearly laterally curved over the margin. A. millefolium: Entyloma achilleae

16a Galls flat-spindle- or ± egg- to jar-shaped; with central larval chamber; caused by midge larvae => 17

16b Galls of different shape, about 1–8 mm long, on leaf blade ± club-shaped, on stem spindle-shaped, often curved, usually green, without larval chamber, often many on leaf blades as well as on stems. Achillea spp.: Subanguina millefolii

17a Galls laterally flattened, egg- jar-shaped, up to 6 (8) mm long, initially green and soft, later brown, finally glossy black and tough. Apically with a narrow, pubescent opening, the lobes enlarging and deflected when mature. One elongated chamber with yellow larva: Rhopalomyia millefolii

17b Galls protruding on upperside, about 2 mm long, oblong egg-shaped to jar-shaped, acuminate, about 4–8 mm long; wall soft paper-like to yellowish-green. Galls open at maturity with several deflected white felt-like pubescent lobes; top with narrow opening. One-chambered, solitary or gregarious. A. ptarmica: Rhopalomyia millefolii

17c Petiole, rachis or midrib of the leaflets with sometimes several, very weak, spindle-shaped, ± reddish galls; occasionally accompanied by slightly curved weak enlargements. Per gall one sulphur yellowish to bright brick red larva. A. millefolium: Lasioptera francoisi

18a Leaves rolled in different ways, twisted or curled => 19

18b Leaf blade on the underside with small depressions; bulges on corresponding upper side. A. millefolium: Craspedolepta nervosa

19a Malformations or abnormal pubescence => 20

19b One or several, stacked leaves on the stunted shoot stem, densely white-silky pubescent; leaf blades ± rolled or curled downwards. Rachis and veins slightly thickened, ± shortened, sometimes bent strongly downwards. A. millefolium: Unidentified gall mite

20a Malformations of usually many densely stacked leaves at the ± stunted shoot tip; caused by aphids or cercopids => 27

20b Leaf blade ± nest-like joined or leaf margin closely rolled downwards => 21

21a Leaflets with narrow, not abnormally pubescent downwards rolled leaf margin. A. erba-rotta subsp. moschata, nobilis: Unidentified gall mite

21b Leaves, depending on size, completely or partially strongly curved, sometimes almost nest-like bent downwards on the stunted shoots with several; usually strongly curled and dark green coloured near the froth-covered larva. Achillea spp.: Philaenus spumarius

22a Sporulating areas dark-coloured => 23

22b Globular to oblong, exceptionally slightly callus-like bulged aecia on the leaf underside or, more rarely, on stems. A. ptarmica: Puccinia vulpinae

23a Sporulating area tough, bulged on leaves; up to 5 mm long, globular to oblong, with brown telia. Strongly infected stems ± bent or twisted => 24

23b Whole plant stunted by shortened internodes, densely bushy, often non-flowering. Stem and leaves with small pustule-like depressions, which cause irregular bends. A. millefolium, ptarmica: Didymaria matricariae

24a On A. millefolium, setacea and closely related species: Puccinia cnici-oleracei

24b On A. salicifolia, ptarmica and closely related species: Puccinia ptarmicae

24c Shining black, less than a mm long elliptic blisters on the stems and undersides of the leaves. A. ptarmica: Schizothyrioma aterrimum

25a Galls of largely defined shape at the tips of sometimes conspicuously stunted shoots, on terminal- or lateral buds; caused by gall midges or flies => 30

25b Malformations of many leaves at the end of main- or ± stalked lateral shoots => 26

26a Malformations not abnormally pubescent; caused by aphids or cercopids => 27

26b Leaves stunted, on the often strongly compressed tips of main shoots or lateral buds ± in dense tuft-like clusters, twisted and at the margins downwards rolled, often ± thickened, sometimes abnormally pubescent. A. ptarmica: Unidentified gall mite

26ca Malformations of terminal twig-parts and leaves. Containing a fly maggot. A. ptarmica: ? Tephritis sp

27a Malformations of rosette leaves or more closely to the tip of usually distinctly stunted stems, or leaflets deflected, ± curled; occupied by aphids => 28

27b Leaflets crooked, irregularly twisted. Whole plant stunted or ± bent. A. erba-rotta subsp. moschata, ptarmica: cf. Psylla ptarmicae

28a Malformations at the tip of well-developed shoots => 29

28b Leaf rosettes dense bushy; leaves malformed in different ways; grey-green aphids between the lobes. A. millefolium: Coloradoa achilleae

28c For A. millefolium and subspecies a causer of similar malformations has been reported, with early dying rosette leaves standing rigidly brush-like upwards and having the leaf segments upwardly directed: Macrosiphoniella usquertensis

29a On A. salicifolia, ptarmica. At the top of vegetative shoots the leaves in large numbers more densely arranged, ± downwardly bent and rolled: Aphis fabae and/ or Aphis fabae subsp. solanella

29b Similar malformations on A. collina, millefolium. Aphid 2.5–3 mm long; body green, covered with grey wax powder: Macrosiphoniella millefolii

30a Tip of shoot, possibly including inflorescences or also lateral buds, changed into a spongy, whitish or reddish, ± globular-oval, smaller or up to 30 mm long, moderately frequently whitish pubescent, multilocular gall, often disc-like framed by some ± shortened and broadened leaves. One white larva per chamber. A. ptarmica, rarely millefolium, ochroleuca: Rhopalomyia ptarmicae

30b Galls laterally flattened, egg- to jar-shaped, about 4–8 mm long; very different in position; their wall soft and green in the beginning, later tough and brown to glossy black. At the rather acute top with a narrow, on the inner surface pubescent opening, the lobes of which are enlarged and deflected at maturity. Sometimes several galls together, also partially connate. One bright yellow to yellow larva per chamber: Rhopalomyia millefolii

30c Bud hypertrophied, transformed into a subglobular gall, woody, plurilocular, covered with a dense whitish pubescence and enveloped by some disfigured and haired leaves. Contains a single red larva: Rhopalomyia achillearum

30d Buds in leaf axils transformed into jar-shaped galls, about 4–8 mm long; their wall soft paper-like to yellowish-green, one-chambered, which open at maturity with several deflected whit felt-like pubescent lobes. A. ptarmica: Rhopalomyia sp.

31a Galls in single florets, on bracts or fruits => 42

31b Malformations of capitula or on the whole inflorescence => 32

32a Malformations of receptacle, or flower head => 39

32b Malformations usually extending over larger parts of the inflorescence => 33

33a Malformations caused by aphids => 38

33b Different gall causers => 34

34a Galls not connate to a consistent locular body => 35

34b Single or occasionally multiple capitula or even complete inflorescences reshaped to small or considerable extent, sometimes up to 30 mm long, more or less rotund to oval, multilocular galls. Wall spongy, whitish or reddish, sometimes pubescent. Galls occasionally framed by a cup of several, partially shortened and broadened leaves. Each chamber with one white larva. A. salicifolia, ptarmica, more rarely A. millefolium: Rhopalomyia ptarmicae

34c Gall midge larvae develop in flower heads of A. millefolium: Macrolabis achilleae

= From Greece on A. millefolium the gall midge Contarinia achilleae has been recorded.

35a Malformations more or less white woolly => 37

35b Malformations without conspicuous pubescence => 36

36a Capitula to a large extent deformed. All flower parts enlarged and more or less curled. Stamens occasionally reshaped to form a second corolla. Bracts more or less enlarged and misshapen. A. abrotanoides, millefolium: Aceria kiefferi

36b Capitula enlarged, more or less distorted, non-flowering. A. millefolium: Thrips nigropilosus

37a Inflorescence completely transformed into a dense white tomentose mass; capitula completely or partially greened. A. erba-rotta subsp. moschata, nana, nobilis, pectinata: Aceria achilleae

37b Similar malformations in A. millefolium: Unidentified gall mite

38a The whole inflorescence stunted in all developmental phases. Capitula staying small, not opening, stacked. Aphid 2.5–3 mm long, body green, greyish frosted: Macrosiphoniella millefolii

38b Similar malformations. Aphid 1–2 mm long, pale yellowish to yellowish-green. A. millefolium: Brachycaudus helichrysi

38a Malformations of receptacle by fly maggots => 40

39b Capitula differently deformed, more or less stunted. Marginal florets occasionally enlarged, distorted, slightly thickened, occasionally containing oospores. Mycelium in many cases later on fruits with dirty grey to violet, branched conidiophores. A. ptarmica: Peronospora radii

40a Receptacle swollen; malformations not affecting the stalk of the flower head => 41

40b Receptacle together with the stalk of the flower head thickened. Infected capitula clearly standing out from the normal ones. A. millefolium: Unidentified fly

41a Receptacle acute-conically swollen, sclerotic; at the upper end with a round opening after the fly has emerged. Containing a single larva. A. millefolium and subspecies, A. ptarmica: Tephritis nigricauda

41b Receptacle similarly but more strongly deformed, conspicuously standing out from the normal capitula. One white larva. A. millefolium: Eurasimona stigma

41c Flower head aborted, inconspicuously disfigured or hypertrophied. Containing a single larva. A. millefolium. Also on Artemisia: Tephritis dioscurea

41d Slight malformation of the flower head. A. maritima: Tephritis stictica

42a In florets and fruits => 43

42b Basal parts of bracts more or less egg-shaped, swollen. One initially white, later on orange larva. A. ptarmica: Rhopalomyia palearum

43a Malformation of single or many florets => 44

43b Ovary or fruit, sometimes also the basal part of corolla, lightly swollen. One yellow larva. A. millefolium, ptarmica (main hosts), biserrata, nobilis, nobilis subsp. neilreichii: Ozirhincus millefolii

44a Several florets deformed in a frequent thick-walled gall, about 3–5 mm long, initially more or less egg-, later jar-shaped, protruding distinctly from the flower head. One yellow larva. Achillea spp.: Rhopalomyia millefolii

44b Many capitula per inflorescence intensely dark red coloured. Flowers often distinctly stalked, hardly swollen, not opening. One reddish larva per floret. A. ptarmica: Unidentified gall midge

= Larvae of Contarinia sp. developing in flower heads of Achillea millefolium, ptarmica have been recorded from Denmark, and ditto on Achillea sp. from Greece

= Furthermore larvae of Jaapiella sp. developing in flower heads of Achillea millefolium have been recorded from Denmark

gallers on Acer

pub 15.xi.2019

Dichotomous table for gallers on Acer

by Hans Roskam

1a On above-ground parts => 2

1b Roots with rotund, single-chambered brownish galls, up to 9 mm across, often gregarious and similarly ± flattened later on and partially coalesced. Wall initially succulent, lignified later on. Each contains a single larva. A. pseudoplatanus: Pediaspis aceris, asexual generation

1c Galls smaller, massive. A. negundo: Meloidogyne sp.

2a Malformations of flowering or fruiting, inflorescences and their parts => 48

2b Malformations of buds, axial parts or leaves => 3

3a On leaves => 13

3b On buds or axial parts => 4

4a Galls on shoots => 6

4b Malformations of buds => 5

5a Buds swollen. A. pseudoplatanus, ? saccharinum: Aceria vermicularis

5b Buds atrophied, widely opened. Inside a crumbly mass. A. pseudoplatanus: Inducer unknown

6a Witches’ broom-like malformations or galls caused by mistletoes => 12

6b More or less distinctly protruding swellings or proliferations on axial parts => 7

7a Malformations mainly on the younger twigs => 8

7b Bark with ± expanded open wounds, with irregularly bulging callus proliferations at their margins. “Nectria-cancer”. Acer spp.: Neonectria sp.

= On various occasions so-called “burrs” have been recorded on the bark of older maple stems. These structures, usually lacking pith, are not true galls, but develop as a response to biotic or abiotic factors.

7c Similar gall-like proliferations are attributed to either Agrobacterium tumefaciens and/ or Phomopsis sp.

8a Inducers inside the galls => 9

8b Bark of younger as well as older side branches with flat, irregularly pock-like swellings. Causer in shallow, rimmed depression. Heavily infected parts additionally thickened and ± stunted. Acer spp.: Chionaspis salicis

9a Galls on bark => 10

9b First- or second-year twigs swollen on all sides below a node. The pith contains a caterpillar; grey-yellow to brownish with dark- to black-brown head. A. campestre, platanoides: Gypsonoma aceriana

10a Galls irregular, up to 2 mm high and 3.5 mm across, tubular-wart-shaped, often on base of one-year twigs. Solitary or gregarious, variously coalesced in the latter case => 11

10b Globular, up to 8 mm across, single-chambered galls on the bark of young twigs. A. pseudoplatanus: Pediaspis aceris, sexual generation

11a On A. platanoides: Aceria heteronyx

11b On A. campestre: Aceria aceriscampestris

= taxonomy of A. heteronyx, aceriscampestris and A. myriadeum is confused. I restrict A. hereronyx and A. aceriscampestris for bark galls on Acer platanoides and campestre, respectively, and A. myriadeum for leaf galls on Acer campestre.

0a Older branches with sometimes giant spindle-, club-, or more barrel-shaped swellings, often arched, bearing the inducer Viscum album

0b Witches’ broom-like malformations. Leaves with a tuft-like cover of dirty white asci during the fruiting of the fungus. A. platanoides: Taphrina acerina

0c Similar witches’ broom on A. campestre: Taphrina acericola

= Other witches’ brooms found on A. platanoides, negundo, pseudoplatanus, saccharinum have unknown causes

13a Malformations of the leaf blade => 15

13b Galls on petiole => 14

14a Galls rotund or thick-spindle-shaped, up to 5 (6) mm thick, one-chambered, thin-walled, yellowish-green, sometimes ± reddened. Containing a single larva. A. pseudoplatanus: Pediaspis aceris sexual generation

14b Slender spindle-shaped, one-sided thickenings, often on upper part, also in the middle of the petiole, rarely on the base of the midrib; 5–10 mm long, up to 2.5 mm thick; usually dark purple to violet coloured. Containing a single white larva. A. campestre: Atrichosema aceris

15a Galls open, sometimes with only a narrow entrance => 20

15b Galls closed => 16

16a Galls flat, protruding about equally on both sides of leaf => 17

16b Galls globular, only on underside, visible on the upper side as a rotund to oblong-oval disc, 6–8 (10) mm across, single-chambered, thin-walled; usually glabrous, yellowish or ± reddened. Galls inhabited by inquilines or parasitoids are often significantly larger, irregular or with blunt tubercles. Containing a single larva. A. monspessulanum, opalus incl. subsp. obtusatum, platanoides, pseudoplatanus: Pediaspis aceris sexual generation

17a Galls larger than 4 mm, rotund in the leaf blade, but acuminate oval on the main lateral veins; caused by gall midge larvae => 19

17b Galls only 1–3 mm across, mite- or midge galls => 18

18a Galls irregular rotund, up to 3 mm across; almost woody, thick-walled; at the upper side protruding more than on the underside; one-, more rarely multi-chambered, opening on underside of leaf. A. tataricum, also A. campestre:
Acericecis szepligetii

18b Leaf blade with pustule-like swellings. A. monspessulanum:
Unidentified gall mite

19a About 4–7 mm wide, round pustule gall. On the underside with an arched, translucent, tender wall; in the middle green, at the margin a little lighter. Often many per leaf blade, sometimes ± coalesced, only exceptionally reaching the main venation. Each pustule contains a single larva. A. opalus, pseudoplatanus:
Acericecis vitrina

19b Galls 4–6 (8) mm wide, browned later on, with small elevation in the middle on the underside. The central larval chamber often situated in a locally swollen side vein. Contains a single larva. A. campestre: Dasineura tympani

19c Similar galls, vacated already mid-July. A. pseudoplatanus: Unidentified gall midge

20a Leaf blade with pouch-like, globular or horn-like galls or with abnormal pubescence. Mite galls => 30

20b Leaf blade otherwise disfigured => 21

21a Leaf blade with slight bulge- to bladder-shaped swellings, with folds, curls or rolled inwards => 23

21b Leaf blade on the underside with small grooves => 22

22a Depression on underside about 1 mm deep, surrounded by a rotund, 5–7 mm wide, lighter area. The depression contains, sometimes enveloped by a droplet, glossy, white, also pale yellow larvae. A. monspessulanum, opalus, platanoides, pseudoplatanus: Drisina glutinosa

22b On Acer campestre. Raised pimple 1–2 mm high on upper side corresponding with depression below; translucent white larva in depression: Acericecis campestre

22c Very flat small grooves on the underside; on the upper side even shallower, initially green, eventually yellowish or brownish bulges, which lack a broad pale surrounding area. A. pseudoplatanus: Unidentified psyllid

23a Leaf blade with bulge- to bladder-like swellings, curls or loose rolls, caused by aphids, cercopids or fungi => 25

23b Folds, curls or leaf rolls caused by gall midge larvae => 24

24a Leaf blade often with blood red weakly thickened folds, which is glabrous on the outside and is situated between two only slightly changed veins. Opening on the underside. Cavity covered with white hairs. Sometimes combined with, or exclusively, a downward roll of the leaf margin. Containing several white larvae. A. campestre, monspessulanum, opalus, pseudoplatanus, saccharinum, etc.: Contarinia acerplicans

24b Leaf blade irregularly folded upwards and ± undulatingly curled; marginally deflected or rolled, often ± reddened. Between the folds on the ± curled, usually ± thickened veins are several white to reddish larvae. Acer spp., also ornamental forms: Dasineura irregularis

24c On A. campestre: Dasineura rubella

= The gall midge Contarinia sp. causing leaf margins bent downward on Acer monspessulanum has been recorded from Greece

25a Malformations caused by aphids or cercopids => 28

25b Leaf blade with weak bladder-shaped swellings, caused by fungi, which develop a tuft-like bloom of asci => 26

26a On A. campestre, pseudoplatanus => 27

26b On A. tataricum, orientale. Leaf blade with several, rotund, yellow to red brown, sometimes a little bladder-like swollen patches up to 1 cm wide. At maturity on the upper side with a bloom of asci: Taphrina polyspora

27a On A. campestre. Leaf blade with several usually distinctly bordered, about 2–3 mm wide, exceptionally slightly arched, sometimes coalescing discoloured patches: Taphrina acericola

27b On A. pseudoplatanus. Sori in several 0.5–3 cm wide, ± bulging discoloured patches on leaf blade: Taphrina pseudoplatani

27c Regarding similar leaf malformations on A. platanoides: Taphrina acerina

= Up to 10 (20) mm long black, inside white, tough patches on A. campestre, platanoides and other Acer species. These are not true galls but consist of overwintering mycelium of Rhytisma acerinum. On several Acer species on living leaves in only small sori in ± yellowish patches, etc. also Rhytisma acerinum

28a Galls caused by aphids => 29

28b Leaf blade distinctly reflexed; curled close to the froth-covered nymph, dark green. A. platanoides: Philaenus spumarius

29a Leaf blade loosely rolled downwards: Drepanosiphum platanoidis

29b Leaves of terminal shoots variously stunted, curled. Acer spp.: Periphyllus testudinaceus

29c Similar malformations are also caused by the next species, only distinguishable by microscopic characters:

= on A. pseudoplatanus: Periphyllus acericola

=on A. campestre, platanoides: Periphyllus aceris

30a Leaf blade with abnormal pubescence, free on the leaf blades or in depressions => 35

= To what extent the next galls, caused by unidentified gall mites, might be induced by several species, needs further study.

30b Galls pouch-shaped, globular or horn-like => 31

31a Galls scattered over the leaf blade => 32

31b In the vein axils on the upper side, more rarely anywhere on the leaf blade 2–4 mm, irregular rotund, glabrous to thick pubescent, ± yellow-brown or reddish, solitary or situated in pairs, often pouch-shaped galls. Opening on underside, like the cavity, clothed with multicellular hairs. A. campestre, less frequent on platanoides, pseudoplatanus: Aceria macrochela

32a Small pustules, usually less than 2 mm and often only up to 0.5 (1) mm wide, mainly on upper side, usually very many per leaf blade and coalescing into dense reddish groups. Opening on the underside, like the cavity, clothed with cylindrical, one- or multicellular hairs => 33

32b Galls horn-like or sometimes pustule-shaped, about 2–3 (4) mm long, yellowish or mostly reddish, mainly on the upper side, several to many. Opening mostly on underside, like the cavity, clothed with 1-celled, cylindrical hairs. On. A. pseudoplatanus, more rare on A. campestre, platanoides, pseudoplatanus, opalus, saccharinum: Aceria macrorhyncha

32c Gall round or elongate with a short, slender neck, 1.5–5 mm high, on veins or leaf blade; surface wrinkled, glossy, yellowish-green at first, becoming dark red to black; opening with single-celled hairs; galls may be very many. A. saccharinum more rare on A. monspessulanum. opalus subsp. obtusatum, tataricum: Vasates quadripedes

33a Hairs within galls 1-celled => 34

33b Hairs in the cavities multicellular, galls often horn-like. A. opalus: cf. Aceria opulifolii

34a On A. pseudoplatanus: Aceria cephalonea

34b Similar galls on A. campestre, ? tataricum: Aceria myriadeum

= taxonomy of A. heteronyx, aceriscampestris and A. myriadeum is confused. I restrict A. heteronyx and A. aceriscampestris for bark galls on Acer platanoides and campestre, respectively, and A. myriadeum for leaf galls on Acer campestre.

34c Similar galls developing on A. monspessulanum: Aceria monspessulani

35a Hairs of the erinea hardly changed or cylindrical, to slender club-shaped, or irregularly branched. Erinea exposed or in oblong depressions => 39

35b Hairs ± distinctly stalked, cup-shaped, toadstool-like or terminally globular, erinea freely extending over the leaf blade => 36

36a Erinea on A. monspessulanum => 38

36b Erinea on other Acer species => 37

37a Erinea on various sites or may cover all of the underside, at first white, then red and finally brown felt mass. Leaf blade may be ± bulged on opposite side. Hairs relatively short, toadstool-, cup- or funnel-shaped. ~, especially on A. campestre, obtusatum, pseudoplatanus, rubrum: Aceria macrocheluserinea

37b The mites free-living on the underside of large-leafed maple species have been taxonomically separated:

a On A. pseudoplatanus: Aceria pseudoplatani

b On A. platanoides: Aceria platanoidea

= Erinea in leaf axils on underside sometimes occur and may be caused by these mites. Other mites may also cause erinea on A. pseudoplatanus and A. campestre. Acer mites need further study

37c Erinea on underside; predominantly in the vein axils; extending from these or also on the upper side of the veins; at first white, then red, finally brown. Arching absent or only weak. Hairs toadstool-, cup- or funnel-shaped. A. pseudoplatanus: Unidentified gall mite

38a Erinea thin and forming flat expansions, often on leaf base or on the venation, rarer on other areas of the leaf blade. Hairs short and finely stalked, toadstool-shaped. The infected areas brown prematurely and dry: Unidentified gall mite

38b Erinea on upper side, rarely on underside, yellowish-white, then reddish or rust brown. Hairs long stalked, toadstool-shaped or also simply elongated: Unidentified gall mite

39a Hairs cylindrical, elongated club-shaped or irregularly branched => 40

39b Erinea with only slightly changed, hardly thickened hairs. Leaf blade not disfigured. A. campestre, platanoides, pseudoplatanus: Cecidophyes gymnaspis

40a Erinea on the underside in vein axils or along the veins => 43

40b Felt masses at various places on the leaf blade, especially in oblong depressions or on arched bulges => 41

41a Erinea in rather flat or strongly curved archings => 42

41b Leaf blade with somewhat oblong depressions, up to 15 mm long and 4 mm wide on underside. Exit on upper side, slit-shaped. With cylindrical, repeatedly curved hairs inside, at first white, later on brown. A. campestre: Aceria carinifex

42a Erinea predominantly on the underside, at first white, later on brown, on various only slightly changed or also upwardly arched, ± oval, also coalescing areas. Hairs relatively long, cylindrical or weakly club-shaped, the apical part sometimes curved or also crooked. A. pseudoplatanus, platanoides: Aceria pseudoplatani

42b Leaf blades of A. illyricum, monspessulanum on the underside with, at first white, later on brown-red felt masses in weak, similar upward archings. Hairs cylindrical: Aceria monspessulani

43a On A. campestre, monspessulanum => 45

43b On A. platanoides, pseudoplatanus => 44

44a On A. plataniodes. Felt masses in distinctly upwardly arched vein axils. Hairs club-shaped: Unidentified gall mite

44b On A. pseudoplatanus. Small tufts of brownish, irregular branched hair on the underside in vein axils or in stripes up to 2 mm wide along the main veins; galls not visible on upper side: Unidentified gall mite

45a On A. campestre => 46

45b On A. monspessulanum. Reddish felt masses on the underside of the leaf blade base along the veins as well as in the vein axils. Hairs slender and club-shaped, variously curved: Unidentified gall mite

46a Small tufts of stalked or terminally weak club-like or nodular thickened hairs in the vein axils; infestation extending up to the midrib and the petiole => 47

46b Erinea only in the vein axils; infestations weakly arched on the upper side. Hairs irregular branched and bent: Unidentified gall mite

46c With reservation, also the malformation reported as “yellow tufts” consisting of longer, widened, densely felt-like hairs, reported as “Erineum abnorme” is caused by Aculops acericola

47a Small rotund elevations in the vein axils, 1–2 mm wide, flatly bulging on the upper side, usually yellowish discoloured. Hairs cylindrical, terminally weakly club- or nodule-like thickened, emerging from leaf blade cells: Unidentified gall mite

47b Small, rotund crumbly elevations of ± stalked slender hairs in vein axils which are not bulging. The infestation expands usually in narrow stripes on the midrib as well as in the petiole: Unidentified gall mite

48a Inflorescences distinctly shortened, compact; flowers vestigial or disfigured. A. pseudoplatanus: Periphyllus testudinaceus

48b Solitary or many flowers, and young fruit disfigured to form a one-chambered gall, rotund, up to 8 mm, initially succulent, later on thin- and tough-walled, yellowish or sometimes reddish, containing a single larva. A. pseudoplatanus, platanoides: Pediaspis aceris sexual generation

48a Disfigured fruits. Acer campestre: Acumyia acericola

48b Swollen flower buds contain up to eight small, pink-coloured gall midge larvae among swollen stamens. A. campestre: Dasineura sp.

gallers on Populus

pub 14.xi.2019

Dichotomous table for gallers on Populus

by Hans Roskam

1a On inflorescences or fruits => 76

1b On vegetative plant parts => 2

2a Gall development restricted to particular organs or their parts => 4

2b More or less witches’ broom-like malformation of complete shoot systems => 3

3a Malformation of all terminal shoots. Usually several galled shoots shortened, somewhat thickened, ± pubescent; apical shoots sometimes slightly elongated. Leaves smaller, margin curled, thickened, yellowish or reddish. Stipules often leafy and ± coalesced with the associated leaf. P. tremula, ? alba: Aceria dispar

3b Expanded erect witches’ broom on side branches; on P. alba, nigra often emerging from the axils of twigs that are still herbaceous: Inducer unknown

4a On leaves, shoot tips or buds => 20

4b On shoot axial parts, sometimes encroaching into the buds, or on roots => 5

5a On young twigs that are one to several years old => 13

5b On older twigs, branches, stems and roots => 6

6a On shoot parts distant from the ground => 7

6b More or less tuber-shaped proliferations, initially soft, soon woody and browned on root collars or on basal stem parts. “Root cancer”. Populus spp.: Agrobacterium tumefaciens

6c Nodule-shaped swellings on young roots of P. alba, nigra: Meloidogyne sp

7a Closed galls inhabited by insect larvae; or malformations induced by mistletoes => 9

7b Conspicuous tuberous proliferations or ± rimmed open cancers; caused by bacteria or fungi => 8

8a Galls laterally protruding from the younger stems and branches, irregular tuberous, soon with cracked surface. “Tubercles”. Populus spp.: cf. Bacillus populi

8b Younger twigs, also older branches and stems with cancer-like wounds, which are surrounded by rim-like ± irregular proliferations of the bark. Populus spp.

a Wounds usually with slime secretions. “Bacterium cancer”: Xanthomonas populi

b Wounds without slimy excretions. During later stages, an open woody area is surrounded by sometimes several ± concentric and fissured rims. “Nectria cancer”: Neonectria ditissima

= From similar cancers have been isolated Botryodiplodia penzigii, which species is likewise able to induce cancers/

= On the other hand, Dotichiza populea, a bark smut, does not cause gall-like cancers

9a Galls only a few cm long => 10

9b Older branches, also stems with expanded spindle-shaped to tuberous swellings from which develop: Viscum album

10a Swellings on ± thumb size thickened parts of branches and twigs. Pith containing larvae with distinct head capsule => 12

10b Similarly situated galls caused by larvae without conspicuous head capsule, living in bark or sapwood => 11

11a Spindle-shaped to oblong swellings several cm long which usually do not envelop the stem; bark initially glabrous, heavily perforated after emergence of the gall midges. Several to many slender larvae, with a sternal spatula, lacking conspicuous mouth parts; in inner bark and outer wood. P. alba, tremula: Rabdophaga giraudiana

11b Swelling due to proliferation of bark and sapwood. Bark of the galls glabrous; with single exit hole later on. Each gall containing in a depression of the sapwood a compact, rotund, greenish-white maggot, provided with vertical, hooked mandibles. Galls one-sided, up to about 1 cm long, ± bean-shaped. P. alba, nigra, incl. var. italica, tremula: Hexomyza schineri

12a Locally raised bumps, usually swelling on all sides. Caterpillar biennial, white-yellow with black-brown head capsule, in pith. Populus spp.: Paranthrene tabaniformis

12b Compact swelling, usually on all sides, up to 25 mm long. Larvae yellowish, in pith. Populus spp.: Saperda populnea

= From GB has also been recorded Saperda carcharias causing swelling and deformation of the stem in older trees of P. tremula

= The caterpillar of Cydia corollana may also induce similar galls

13a Galls contain animals => 14

13b Bark of young twigs with irregular, rimmed depressions, which contain the flat froth-covered nymph, covered by a pear-shaped scale up to 2.5 mm long. P. tremula, nigra etc.: Chionaspis salicis

= The polyphagous “Oyster shell scale” Diaspidiotus ostreaeformis (living under a rotund, ± dark grey scale, exceptionally causes similar but much less conspicuous malformations on P. alba, nigra, tremula

= Also the “Poplar armoured scale”, Diaspidiotus gigas occasionally causes similar damage to woody twigs of poplar and aspen

14a Oblong or pouch-shaped galls => 15

14b Bark of young shoots with a double row of egg capsules (procecidia: oviposition scars, not true galls): Nematus miliaris

15a Galls elongated; ± spindle-shaped and predominantly on all sides. Larvae with distinct head capsule => 18

15b Galls rotund to pouch-shaped, one-sided => 16

16a Galls caused by aphids => 17

16b Swelling on the petiole of the leaf, rotund, with short conical tip, which opens at maturity; occasionally with several, coalescing to varied extents and causing bending of the leaf blade. Each chamber containing a red-yellow larva. P. tremula, rarer canescens, alba: Contarinia petioli

17a Gall at the base of present-year shoots, up to 20 mm long, oblong pouch-like, laterally somewhat compressed, initially green, later on ± lignified. Opening at the gradually tapering tip, bent downwards halfway or laterally. P. nigra, as well as var. italica. Ornamental poplars have also been recorded as primary hosts: Pemphigus borealis

17b Galls similar, usually slightly larger, always more strongly bent. Exit hole almost reaching the place of attachment. P. nigra and var. italica, robusta: Pemphigus immunis

18a Galls caused by sawflies; gall usually not completely enveloping the twig => 19

18b Gall shape different, slender to bulging spindle-shaped; usually enveloping the twig. In the pith is a several cm long cavity, which opens by a circular hole into a projecting cigar-like, frass-covered, silken tube. Containing a brownish caterpillar with dark- to black-brown head and neck shield. Populus spp,: Gypsonoma aceriana

18c Similar galls. P. nigra, x canadensis: Gypsonoma dealbana

19a Swellings slightly prominent. The pith containing a single larva. P. tremula: Inducer unknown

19b Pronounced, short oval, blister-like swellings; solitary or several coalescing into tubercular bulges. Larval chamber oblong, in pith. P. nigra, tremula: Inducer unknown

19c Less pronounced malformations caused by egg batches: Stictocephala bisonia

20a On leaf blades or petioles => 28

20b On shoots or buds => 21

21a On shoots => 25

21b On buds => 22

22a Pouch-shaped galls, ± curved, initially green, later on lignified and browned, which open at their apex. Caused by aphids. Sometimes with several together.

22b Galls caused by other inducers => 23

23a Galls caused by gall midges or mites => 24

23b All parts of the opening bud severely stunted, disfigured, up to about 3 cm long. Stem parts sometimes slightly swollen and densely covered on the underside with orange-yellow uredinia, like the leaf rudiments. P. alba, tremula: Melampsora populnea

24a Buds weakly disfigured; more compact, not opening. Containing a single red larva. P. alba: Dasineura populnea

24b Buds are changed into a large mass which is similar to ‘bedeguar’ on rose; inside a chamber containing yellow-white midge larvae. P. tremula: Macrolabis bedeguariformis

24c The dormant buds of lignified shoots, especially on coppice close to ground, or of young, and more rarely also the ± higher situated buds on older stem parts, grow up to about 20 (35) mm long, initially succulent, cauliflower-like accumulations, ± finely partitioned, yellowish or often reddened and sometimes pubescent proliferations. Aceria populi

25a Tuft-like accumulation of several disfigured leaves on the markedly stunted shoot tips; caused by aphids => 26

25b Looser accumulations of curled and curved terminal leaves; larvae on underside. P. alba, canescens: Sthenarus rotermundi

26a Up to fist-size tufts of paler, broadly-bulging swollen shoots often with thickened stalk; on P. alba and forms => 27

26b On P. tremula, x canescens. Petiole bent backwards; leaf blades deflected, ± overlapping: Pachypappa tremulae

26c Large pale green, yellowish to slightly reddish blister-like galls, open to the underside, on leaves of P. tremula: Pachypappa populi

27a Leaf blades ± bladder-like swollen and often bleached: Pachypappa vesicalis

27b Malformations similar to those caused by the previous aphid: Pachypappa warshavensis

28a On leaf blades => 41

28b On petioles => 29

29a Swelling on the basal part of the petiole as well as on the leaf pad, or laterally compressed galls immediately below the leaf blade base, up to about 8 mm long, slender. In the latter case the larvae produce short, spot-like mines with frass arranged in two rows in the immediately adjacent leaf blade => 36

29b Malformation of undefined condition or many small egg capsules next to each other on the side of the petiole => 30

30a Bag- to pouch-like or oval to almost globular, ± smooth-walled galls => 33

30b Gall wall twisted screw-like or swellings arranged like string of pearls on the sides of the petiole => 31

31a Petiole broadened; the bands in loose coils tightly coalesced into a wide spindle-shaped gall; sometimes reddened => 32

31b Minute semi-oval swellings on the upper side, soon developing a slit, in tight series arranged next to each other, usually on both sides of the stalk, often over its complete length and remaining recognizable as swellings after the larvae have eclosed. “Procecidia”: oviposition scars, not true galls. Especially on P. tacamahacca, tremula, also on P. alba, canadensis, candicans, nigra etc.: Cladius grandis

31c Similar swellings: Pristiphora compressicornis

31d Swollen egg capsules, usually in a low number, containing several eggs in spring on petioles as well as on young shoots of poplars: Rhytidodus decimusquartus

32a Gall is green, reddish or yellowish, smooth, formed by thickening, flattening and spiral twisting of petiole with the number of twists not exceeding 5 (usually 3–4), 10‒25 x 7‒10 mm. P. berolinensis, nigra and var. italica, rarer on ornamental forms, hybrids: Pemphigus spyrothecae

32b Galls smooth, shiny, green mottled with red, caused by swelling. Flattening and spiral twisting of the leaf petiole, similar to those of P. spyrothecae but usually thinner and with more and smaller twists (more than 5), about 30 mm long. P. nigra and more often on var. italica: Pemphigus protospirae

33a Galls less than 1.5 (2.0) cm long, wall ± glabrous => 34

33b Galls more than 3 cm long, sometimes at the base of the present year shoot up to hen egg size, provided with many, irregular, ± tubular proliferations, especially towards the top. P. nigra, suaveolens: Pemphigus vesicarius

34a Galls longer than broad, ± pouch- or pear-shaped; induced by aphids => 35

34b Almost globular, up to 5 (8) mm across, sometimes slightly pubescent and reddened, one-chambered gall, which is occasionally narrowed at both ends and laterally with a conical appendage. At maturity with round opening. Sometimes with several ± largely coalesced. Each chamber containing an orange-coloured larva. P. alba, canescens, tremula: Contarinia petioli

35a Galls ± oblong, pouch-shaped, especially apically increasingly narrowing, not or slightly curved; on upper or lower part of the petiole; up to 15 mm long, reddish and lignified. Exit hole on top, surrounded by a somewhat thickened rim. P. berolinensis, canadensis, deltoides, nigra (especially var. italica), robusta, simonii, tacamahacca, etc.: Pemphigus bursarius

35b Globular galls at the base of a green shoot, green, red around the exit opening. The gall is up to 2.5 cm large, and invariably solitary. P. nigra incl. var. italica: Pemphigus trehernei

= Closely related aphids are Pemphigus borealis and Pemphigus immunis

36a Galls on the upper part of the petiole; from 8 onwards => 37

36b Basal part of petiole and bud pad swollen, exit hole later on the base of the leaf pad. P. tremula: Cause unknown – ? gall midge

37a In autumn the mature larvae in the laterally compressed gall make a short, compact, mine on both sides tunneling into the leaf blade base. Each mine containing a single larva. Infected leaf blade segments remain :green islands” of chlorophyll in the otherwise yellowing leaf => 38

37b The older caterpillar encroaches by scraping from the usually cylindrical gall into the base of the leaf blade between two veins on the underside. Feeding sites net-like; on P. alba usually ± covered by the remains of the felt-like pubescence. No preservation of chlorophyll in the infected leaf: Gypsonoma oppressana

38a On P. alba and tremula. Nepticulid larvae living initially in slightly disfigured petioles; transfer to leaf mining when almost mature => 39

38b On P. canadensis, nigra and var. italica: Ectoedemia hannoverella

39a On P. alba, canadensis => 40

39b On P. tremula: Ectoedemia argyropeza

40a The larva constructs its later mine in the axil between two leaf veins. Ectoedemia turbidella

40b The mine is located on a vein instead of in the axil between two veins and protrudes laterally into the leaf blade: Ectoedemia klimeschi

41a Leaf blade folded over the midrib on both sides without distinct thickening, or leaf blade with conspicuous folds or rolls of the margin => 66

41b Malformations different => 42

42a Globular to oval smaller to conspicuous pocket-, pouch-, sac-shaped galls, provided with narrow entry, of defined form, and different size => 55

42b Leaves either with small warts, or humped proliferations at the base of the leaf blade; these with erinea, or bulge- to bladder-like swellings of various sizes on sometimes ± nest-like accumulations of leaves => 43

43a Nest-like accumulation of leaves; variously shaped and curled; moderately pubescent flat bulges or wide opened bladders; additionally associated with curving of the leaf blade => 49

43b Warts, grooves, erinea on the normally unfolded leaf blade or proliferations at the base of the leaf blade => 44

44a Whitish, reddish to brownish or creamy white to yellow erinea => 47

44b Grooves, warts or pustules in the free part of the leaf blade or bumpy bulges on the base of the leaf blade => 45

45a Grooves, warts or pustules on the leaf blade => 46

45b Glands of base of the leaf blade transformed into irregular, rotund to long oval proliferations, up to 4 mm long, bumpy, ± reddened. P. tremula: Eriophyes diversipunctatus

46a Small, 1–1.5 mm broad, flat upward protuberances on the usually normally coloured leaf blade. P. nigra and var. italica: Trioza sp.

46b Many ± golden-yellow warts, less than 1 mm across, on the underside of only the basal leaves: Synchytrium aureum

= On higher leaves, occasionally occur inconspicuous small, oval, two-sided, old pustules, the egg batches especially of sawflies. More conspicuous are the “procecidia”, oviposition scars, not true galls, of the sawfly Pristiphora conjugata, which occur isolated, often many, between the teeth on the leaf margin. Mature caterpillars are green with black-brown head capsule; first- and last segments with clearly defined red or yellow colouration. On willows as well as poplars.

47a Felt-like, white, red to brown erinea of many-celled, hair-like protrusions => 48

47b Leaf blade with one, or several protrusions, up to about 5 (10) mm broad, flat bladder-shaped, pale- to yellow-green upwardly, exceptionally downwardly, projected. Arching at ripening of spores, with extended erinea consisting of densely arranged, almost cylindrical, golden-yellow asci: Taphrina populina

48a Erinea whitish, greenish or yellowish, only rarely reddish, black-brown when old; often arched on the upperside (occasionally also on underside), ± discoloured, on the underside about 5–6 mm broad, rotund grooves, on both leaf surfaces; sometimes clustered and additionally disfiguring the leaf blade. Outgrowths multi-cellular, on top ± widened. P. tremula, much rarer on P. alba, canescens, nigra var. italica: Phyllocoptes populi

= And the probable inquilines Aculus reticulatus and A. aegirinus

48b Initially red, brownish felt masses later developing from short-stalked, abundantly tree-like branching, haired tufts, mainly on the underside, but also on the upperside of the leaves. Erinea sometimes ± depressed. P. tremula: Aceria varia

49a Curling, arching or bladder-like swelling of the leaf blade => 50

49b Leaves on young shoots in spring slightly changed, or the leaf blade over its length ± folded upwards and clustered, nest-like, due to severe bending of the hardly swollen petioles. P. tremula, occasionally x canescens: Pachypappa tremulae

49c Similarly, on P. alba, canescens, euphratica: Pachypappa warshavensis

50a Leaf blade with localised curls, or expanded, flat bulge-like, swellings => 54

50b Leaf blade completely, or partially with conspicuous strongly bladder-like arched swellings wide open on the underside. Contain waxy aphids 5–7, often spilling out of gall, which is not closed => 51

51a On P. alba, tremula => 52

51b On P. nigra and var. italica. Conspicuous broad bladder-shaped wide open swellings, on the underside on both sides of the midrib, on the basal leaf blade, apically and marginally decaying: Pachypappa marsupialis

52a On P. tremula => 53

52b On P. alba, x canescens. Nest-like clustered leaves with bladder-like leaf blades on the short shoots of usually tree-like hosts: Pachypappa vesicalis

53a On saplings. Bladder-like swelling and upward arching of the leaf blade, in cross section up to 7 cm long; venation conspicuously protruding on the discoloured gall: Pachypappa populi

53b Leaves of older trees sometimes disfigured into a large pouch-shaped gall, up to 10 cm long, often situated rather high up in old trees and therefore hard to find. The gall is formed from a longitudinally folded leaf which is paler than the normal leaves and becomes much enlarged with a thickened petiole: Gootiella tremulae

53c Conical leaf-galls. P. alba: Gootiella alba

53d Leaf blade folded down over its length to form a cone, discoloured bright red-orange. P tremula: Pachypappella lactea

54a Leaf blade, slightly arched upwards or downwards, depending on the position of the insects. P. nigra and related species, also P. balsamifera: Chaitophorus leucomelas

54b Leaf blade locally strongly curled; often darker green where the aphid feeds. The respective venation variously bent downwards with the adjacent margin less disfigured leaf blades. P. tremula: Philaenus spumarius

55a Globular, rotund, rarely ± bulge-like galls, less than 8 mm long. Caused by gall midges => 58

55b Sac- or pouch-like galls, often more than 1 cm long of ± defined shape but different size; caused by aphids => 56

= The eggs of the Cerura virula are usually laid in pairs on the upper surface of the leaves of willow and poplar and resemble small galls

56a Galls longer than wide => 57

56b Egg-shaped- or irregularly bulging, smooth-walled galls, distinctly narrowed at their base on the upperside of the leaf, predominantly at the base of the leaf base; opening on the upperside. P. nigra and var. italica, trichocarpa: Pemphigus populi

57a Pouch-shaped gall, about 20 mm long and the upper half up to about 10 mm wide, yellowish or usually reddened on, or immediately next to the midrib. Slit-shaped opening on the underside. P. nigra and var. italica, occasionally P. deltoides, tacamahacca: Pemphigus populinigrae

57b Galls and hosts similar to the above. Aphid differs by its migration to the roots of Apiaceae:

a Alternating on Daucus species: Pemphigus phenax

b Alternating on Carum carvi, exceptionally on Aegopodium and Daucus: Pemphigus passeki

c Alternating on Aethusa cynapium: Pemphigus gairi

58a Galls on one side of leaf only, usually distinctly developed on the upper side; on the opposite side not protruding or, with slightly rimmed exit hole => 64

58b Galls distinct on both sides of leaf => 59

59a The gall opens by a slit when mature; a separate inner gall is absent => 62

59b Ripe gall with a round opening; usually with distinct inner gall => 60

60a Galls relatively thick-walled, about 4–5 mm across, protruding on both sides of leaf. Inside is an oval inner gall, with its longitudinal axis along the longitudinal axis of the leaf blade => 61

60b Galls thin-walled, nodular or flat bladder-like, rotund, up to ± 3 mm across, surrounded by a narrow, ± acute wall; often next to a main vein, which is somewhat thickened and bent. Large cavity with an oval inner gall in the centre, orientated perpendicular to the leaf blade. Containing a single sulfur-yellow, later on red larva. Exit hole usually on the upper side. P. tremula: Harmandiola pustulans

61a Galls greenish to reddish; ± hemispherical on the underside. Larva pale yellow to orange-coloured, sometimes migrating outside the inner gall before maturity. P. alba, tremula: Contarinia populi

61b Galls similar, slightly smaller, usually protruding on the upperside, centrally with slight blunt-conical projection; more rarely protruding on the underside. Larva orange. P. alba, x canescens, tremula: Lasioptera populnea

62a Galls thin-walled, usually only 2‒3 (4) mm across, slightly protruding on the underside => 63

62b Galls thick-walled, oblong-rotund; usually up to about 5 mm across, pale green or ± reddened, single-chambered; only a third of its dimension protruding on the upperside; usually situated next to a vein. Exit hole parallel to the vein; on the upperside ± lip-like surrounded by a circular wall. Larva orange-coloured to pale yellowish-brown. P. alba, x canescens, tremula: Harmandiola cavernosa

63a Galls similar, but thin-walled and less protruding on the upper side, about 3–4 mm across. Larvae yellowish-red to brownish. P. alba, tremula: Harmandiola populi

63b Galls almost perfectly globular, only up to 2 mm across, lacking circular wall, P. tremula: Unidentified gall midge

64a Galls distinctly constricted at base => 65

64b Base of galls only slightly narrowed, not constricted, rotund, up to 2.5 (3) mm across, thin-walled, usually dark red coloured, single-chambered. Exit hole on underside. slit-shaped, surrounded by a ridge. Often several per leaf blade. Larvae reddish-yellow. P. alba, x canescens, tremula: Harmandiola globuli

65a Galls about (3) 4–5 (6) mm across; globular, with distinctly narrowed base; thick-walled, often dark red, single-chambered. Exit hole on underside surrounded by a narrow rim. Containing a single pale to dark orange-red larva. P. alba, x canescens, tremula: Harmandiola tremulae

65b Smaller to larger galls on P. tremula, similar to those of both previous reported midges, but predominantly on the leaf underside; circular wall surrounding the exit hole often present, sometimes lacking. Unidentified gall midges

66a Leaf margin rolled over different, often extensive length => 69

66b Leaf blade with locally defined valve-like marginal folds, or halves on the midrib folded downwards => 67

67a Largely discoloured downward folds of the often yellowish or orange-coloured halves of the leaf blade => 68

67b Local, 10–20 mm long, often under 10 mm deep valve-like fold of the leaf margin on the lower leaves of a young shoot caused by the fundatrix of Thecabius affinis

= In similar, up to now not discriminated folds lives also the fundatrix of Thecabius lysimachiae

68a On a wide range of Populus spp.: Thecabius affinis

68b On P. tremula living in similar folds: Gootiella tremulae and/ or Chaitophorus populeti

69a Loose, thick rolls of the leaf margin, in cross section usually not much over 2.5 mm long. Caused by aphids or gall midges => 71

69b Narrow, slender, more compact leaf rolls => 70

70a Leaf margins without abnormal pubescence, rolled upwards.P. tremula: Aceria dispar

70b Leaf blades, especially of suckers, with narrow upward rolls, which show on both leaf sides a dense encroaching pubescence, occasionally also extending onto the petiole. P. tremula: Unidentified ? gall mite

71a Leaf margin rolled upwards => 73

71b Downward roll of leaf margin => 72

72a On leaves of the ± stunted apical shoot of P. tremula, x canescens: Chaitophorus populeti

72b Corresponding malformations on P. alba, caused by a similar looking aphid: Chaitophorus populialbae

73a Extended upward roll; caused by gall midges or aphids => 74

73b Margin rolled upwards; caused by psyllids. P. alba, canadensis, nigra and var. italica, tremula, etc.: Camarotoscena speciosa

= The psyllid Camarotoscena subrubescens, causing similar malformations on P. alba, nigra, has been recorded from warm regions

74a Curled rolls of the leaf margin, often involving both halves of the leaf blade over extended or complete length; however, at least in its lower part not reaching the midrib. Usually on terminal leaves of current year shoots. P. tremula, alba => 75

74b Mostly one-sided leaf roll which usually involves half of the leaf blade. P. nigra: Thecabius lysimachiae

75a Leaf rolls glabrous, glossy and not excessively pubescent; in various instances they are sickle-shaped. Larvae white, jumping. P. tremula: Contarinia tremulae

75b Roll ± distinctly pubescent; predominantly on leaves of suckers. Larvae white, gregarious, non-jumping. P. tremula, rarely P. alba, x canescens: Dasineura populeti

76a Single fruits of the inflorescence greatly enlarged, concave. Wall thickened, ± discoloured yellowish. P. tremula, occasionally also on P. x canescens, tremula subsp. grandidentata, sieboldii, tremuloides: Taphrina johansonii

76b Corresponding galls on P. alba. Asci usually distinctly larger than in the previous fungus. Taphrina rhizophora

= Variously shaped malformations of catkins are usually caused by lepidopteran or beetle larvae, which bore in the rachis. The catkins (preferably the female ones), become disfigured and drop prematurely.

gallers on Galium

pub 14.xi.2019

Dichotomous table for gallers on Galium

(incl. Asperula, Cruciata, Crucianella)

by Hans Roskam

1a On parts above ground => 2

1b Subterranean buds transformed into a brownish gall, up to 4 mm long, tapering to a short tip, sometimes single, sometimes several united into larger complexes. Containing a single whitish larva. G. mollugo: Ametrodiplosis auripes

2a Galls in inflorescence primordia, inflorescences, or single flowers, or, fruits => 57

2b Galls on vegetative organs => 3

3a Galls compact, on shoot tips, axillary buds; bud-like or tuft-like => 36

3b Axial parts of leaves with localised to extensive galls or malformations on many leaves, which are more densely accumulated on ± stunted stems, but not in tuft-like clusters => 4

4a Malformations involve either shoot parts and leaves simultaneously, or organs with localised sori of fungi, curled leaves, leaf rolls, erinea => 33

4b Gall formation confined to minor or extensive parts of stems; leaves usually not involved => 5

5a Malformations usually restricted to a part of internode, or a node, rarely larger than 10 mm => 7

5b Malformations variable in extent, usually over several internodes => 6

6a Basal shoot parts, especially on seedlings, severely stunted and spongy. Axial parts of older plants over ± expanded areas spongy thickened, sometimes distorted; galls on surface ± wrinkled; inserted leaves ± reduced and often with stalks and basal vein parts similarly swollen. G. aparine, verrucosum: Ditylenchus dipsaci

6b Several internodes usually swollen on all sides, with glabrous surface, constricted at nodes. Black sori developing in rind gleam lead-grey. G. mollugo, verum: Melanotaenium endogenum

7a Galls mostly of definite shape, caused by gall midge larvae => 8

7b Rotund-oval to elongate spindle-shaped, pale-green swellings, slightly protruding, on one side in various positions on internodes. Containing lighter spores. G. palustre: Physoderma vagans

8a Single galls smaller than 3 (4) mm => 9

8b One-chambered, rotund to oval swellings, about 4–10 mm long, fleshy-succulent to spongy, whitish or ± reddish especially on upper stem parts, also on inflorescences, often above a node; occasionally only overtopped by the final, distorted whorl of leaves. Often with several together and variously joined. At maturity ± star-shaped, rupturing with broad lobes. Aperture inside pubescent. Containing yellow to orange-coloured larvae. G. mollugo, sylvaticum, verum etc.: Geocrypta galii

9a Gall body ± enveloped by rind tissue, or protruding parts thin-walled => 11

=Some of following stem galls, reported for unidentified gall midges, might be confused with immature stages or galls of Geocrypta galii, disfigured by inquilines or parasitoids

9b Galls protrude distinctly from rind; wall fleshy => 10

10a Galls up to 5 mm across, situated below a node; often reddish marbled; – rupturing star-shaped. G. pumilum: cf. Geocrypta galii

10b Up to 3 (4) mm long, whitish fleshy galls with elongated conical top, usually situated close to shoot tip below the upper node; open laterally at maturity. G. anisophyllon, mollugo, pumilum, sylvaticum, verum, etc.: Dasineura sp.

11a Distinct swellings of epidermis => 12

11b bove the hardly swollen epidermis, and close to a node as on often curved internode, flat valve-like, up to 2 mm long and hollow, with nose-like elongation in the middle, inserted on small protruding pale socket, proliferations above an inconspicuous larval chamber. G. aristatum, mollugo, verum: Geocrypta rostriformis

12a On G. aparine: rotund to short spindle-shaped, one-chambered swellings situated above a node. Containing a single larva: Unidentified gall midge

12b Thin-walled gall on G. verum: below, or rarely above node, up to 2 mm long, yellowish, causing localised stunting, thickening and curving of the shoot axis: Unidentified gall midge

13a Stunting of axis associated with ± conspicuous accumulation of leaves; also erinea on various organs or curling, or rolling of leaves caused by animals => 23

13b Local, variously shaped swellings on shoot axis and leaves, caused by fungi => 14

14a Spores of fungi develop on surface of galled tissue => 16

14b Fruiting bodies develop inside gall => 15

15a Wart-shaped multicellular galls, up to 1 mm long, often arranged in rows or coalescing into crusts, almost only on lower, additionally little disfigured stem parts and on undersides of leaves. The warts consist of a strongly hypertrophied, slightly discoloured nutritive cell and similar auxiliary cells. G. mollugo: Synchytrium globosum

15b Similar multicellular, wart-shaped galls, associated with conspicuous additional malformations of infected organs. Belongs to the species complex of S. aureum. G. anisophyllon, boreale, palustre: Synchytrium galii

16a Malformations caused by rust fungi => 17

16b Malformations, according to extent of etiolation, running ahead, exhibiting elongated internodes and narrowed pale-green leaves, covered by down of branched conidiophores on underside. Assigned to facultatively disfiguring micro-species of the species complex. Asperula tinctoria, and with ± specialised micro-species on Galium: Peronospora calotheca species complex:

a On G. boreale, mollugo, palustre, saxatile, sylvaticum, uliginosum, verum: P. galii

b On G. aparine, spurium: P. aparines

c On Asperula purpurea: P. insubrica

17a Rust fungus develops several spore types during life cycle => 19

17b Fungus develops only telia, partially on pad-like swellings on leaves, partially on shoot axis on spindle-shaped, on one or all sides, rather conspicuous swelling => 18

18a Bulging, covered with black-brown spores, ± distorted swellings on stems and leaf axis or pad-shaped swellings on leaf blades. G. saxatile, pumilum: Puccinia lagerheimii

18b Malformations similar, spores lighter; germinated sori grey-brown. Cruciata laevipes, Galium mollugo, saxatile, sylvaticum etc.: Puccinia galii-verni

= From Arctic areas have been reported on leaves and stems of G. boreale: Puccinia rubefaciens

19a Fungus develops all spore types (one type may be absent) on same host => 20

19b On Galium only spermogonia and aecia of a host-alternating rust fungus develop. G. mollugo: Aecidium molluginis

= From G. boreale an isolated aecium has been described as Aecidium molluginis.

20a All spore types develop or spermogonia, and uredinia are absent => 21

20b Aecia absent. On Cruciata laevipes, paedemontana, etc.: Puccinia galii-cruciatae

20c Similar on G. scabrum: Puccinia galii-elliptici

21a All spore types present or only spermogonia absent. Also fungi with partially unstable succession of spore types, especially on respective secondary host => 22

21b Uredinia absent from life-cycle of this fungus which is distinguished by repeated development of aecia. Galls especially on stems and leaf veins. G. aparine, spurium: Puccinia difformis

22a Often all shoots of a plant stiffly extending, strange-looking, sterile. Leaves shortened, broadened, ± deflected; covered by densely arranged spermogonia and aecia, mainly on underside. Sori occasionally also on leaf upperside and stem. A. tinctoria, ciliata: Puccinia asperulina

22b Known from many Galium species, almost Cosmopolitan, developing all spore types on main host: Species complex of Puccinia punctata

23a Malformations on leaves, partially also occurring on stems, are associated with excessive pubescence or leaves have tight, narrow rolls of margin; caused by gall mites => 52

23b Malformations of leaf-bearing shoots, encroaching onto developing inflorescence, without additionally very dense pubescence or narrow roll of leaf margin, mainly caused by hemipterans, thrips or mites living on surface => 24

24a The very variable malformations bear aphids => 29

24b Malformations caused by other animals => 25

25a Malformations caused by psyllids, mites or spittlebugs => 26

25b The terminal, young leaves are variously rolled, twisted, distorted, discoloured and occasionally weakly bulging and thickened; Cruciata laevipes, Galium verum: Unidentified thrips

26a Malformations caused by psyllids or spittlebugs => 27

26b Plant completely or mainly of compact growth, lacking the typical thickenings of stem. The whorls of leaves deflected over the tip, mainly normally coloured and not excessively pubescent. Leaves are densely clustered on main shoots which may be excessively branched, giving the diseased shoot an truncated pyramidal outline. G. mollugo, verum: Inducer unidentified – ? gall mite

27a Malformations caused by psyllids => 28

27b The usually terminally infected shoot is stunted close to infestation and ± bent; the leaves inserted there are clustered and variously deflected and twisted. Infestation of generative shoots or inflorescences results in their stunting and to accumulation of all inserted parts: Philaenus spumarius

28a Cruciata laevipes. Longitudinal growth of several terminal internodes stunted. The stunted and slightly thickened stems bear accumulated shortened and broadened, inwardly curved, densely pubescent leaves. With several flat froth-covered nymphs: Unidentified psylli

28b On Galium and Asperula species. Leaves of clustered upper whorl thickened, margin ± strongly bent inwards or leaf blade disfigured, spoon-like. Often reddened and united to a rotund- to oblong-oval complex of galls. Trioza galii species complex. Note: key for adults:

a Galls on buds, stems and leaves of Galium, Rubia and Sherardia spp. Forewing membrane of adults lacking spinules except for the base of CU2. Trioza galii

b Similar malformations. Galium spp. Forewing membrane of adults with spinules present in all cells forming more or less extended fields: Trioza velutina

29a Aphids green to reddish or brownish => 31

= The aphid galls occurring on Galium are very variable, the causers are mainly oligo- to polyphagous. Identification only according to characters of the aphids.

29b Aphids dark-green to black => 30

30a Siphunculi often as long as, or slightly longer than cauda, at most only slightly shorter. Aphids usually only in small, stacked, balls of leaves, mainly on shoot tips, leaves distorted and ± twisted. G. aparine, spurium: Aphis fabae and/ or Aphis fabae subsp. solanella

30b Siphunculi of wingless aphids about a third as long as cauda. Leaves on stunted shoot tips ± clustered, roll-like; leaf blades distorted and twisted. Especially on G. mollugo: Aphis galiiscabri

31a Antennae longer than body => 33

31b Antennae about ¾ of body length or longer, at least reaching siphunculi => 32

32a Shoot stunted. Leaves of terminal shoots deflected. G. mollugo: Myzus persicae

32b The only slightly stunted shoots have loose whorls with deflected leaves. G. mollugo: Aulacorthum solani

33a Siphunculi slender, as long as, or longer than cauda => 34

33b Siphunculi of unwinged aphids short, thick and conical, shorter than cauda. Aphid pale greenish, yellow-brownish to dark ivory-coloured. Froth-covered nymph not red. Shoots terminally or inflorescences weakly stunted. Leaves of young whorl deflected. Asperula purpurea, G. mollugo, rubrum, verum: Staegeriella necopinata

34a Legs dark brown-black, siphunculi dark brown and about as long as the finger-shaped brown-black cauda. Aphid bicoloured with ± reddish thorax and olive-green abdome => 35

34b Siphunculi of unwinged aphids pale, at least twice as long as the triangular and also unpigmented cauda. Legs of apterae pale. Aphid 2 mm long, green to pale reddish. Shoots terminally severely stunted. The leaf tips are deflected in the terminally clustered whorls. G. mollugo, verum: Myzus langei

35a Shoots terminally stunted, whorl develops ± dense ball. G. austriacum, verum: Hydaphias molluginis

35b Shoot slightly stunted, with slightly deflected or occasionally not disfigured leaves. G. mollugo: Hydaphias molluginis

36a Galls develop from swellings of shoot tips or from swollen bases of densely clustered leaves, or they are shaped as ± loose tufts, which consist of a large number of ± transformed, not conspicuously haired leaves with freely ending leaf blades => 40

36b Galls consist only of leaves, which are bud-like or consist of almost closed structures; leaf blades are reduced or rudimentary => 37

37a Globular or oval galls, ± rounded at tip, up to 5 (6) mm, emerging from only a few whorls of leaves; midge galls => 38

37b Extensive bushy malformations, often appearing excessively branched, with strongly reduced leaves terminally on vegetative shoots or leafy generative shoots. G. mollugo, verum, etc.: Aculus anthobius

37c Galls up to 15 mm long and 8 mm broad, hollow, ± pubescent and stalked, roughly conical, or pear-shaped with beak-like appendage; many irregular proliferations inside with mites living in between. G. glaucum, mollugo, saxatile, verum, etc.: Aceria galiobia

38a More or less globular or egg-shaped galls containing yellow, non- jumping midge larvae at maturity => 39

38b Upper whorl clustered, tuft-like on severely stunted stem. Basal leaves broadened, disc-like ± discoloured, transformed into an artichoke- to bud-like gall up to 6 mm broad. Containing glossy, jumping, orange-red larvae. Asperula tinctoria: Contarinia asperulae

38c Shoot tip severely stunted. Axial parts and leaves swollen, spongy. All parts largely joined into a rotund gall, up to 6 mm long. Containing orange-red larvae. Asperula cynanchica, tinctoria, Crucianella angustifolia, Galium glaucum, odoratum, etc.: Dasineura asperulae

38d Egg-shaped, 2–4 (6) mm long gall, consisting of 2–3 whorls, usually terminally on side shoots, containing pale red larvae. G. mollugo: Dasineura sp.

38e Galls similar; often several joined into 10–15 mm long, ± barrel-shaped complexes. Each gall containing several larvae, pale orange-yellow at maturity, non-jumping. G. glaucum: Geocrypta sp.

38f Similar galls on G. boreale with 1–3 pale dirty-yellow larvae: Unidentified gall midge

38g Stem- or shoot galls on G. glaucum:

a Axial parts on tip of main- or side shoots severely stunted. leaves of several whorls densely clustered, shortened, especially the outer ones basally strongly broadened, slightly discoloured and with, contrary to the inner ones, only short, erect tips. Contain several pale orange-yellow, non-jumping larvae at base of 3–5 mm broad, rotund to cylindrical, sometimes slightly twisted malformations: Unidentified gall midge

b Axial parts with one-sided, 2–3 (4) mm long, laterally flattened, thin-walled proliferations of rind, the middle, usually yellowish-green part distinctly narrowed and crooked. Galls situated on internodes; on youngest shoots sometimes completely taking the severely stunted and at gall-free side convex curved internode. An oblong larval chamber containing a single pale to yolk-yellow, non-jumping larva: Dasineura sp.

39a Almost globular, often reddened galls, up to 4 mm long. The four leaves of the subapical whorl are greatly shortened and broadened, the severely disfigured, ± succulent, often calyx-like leaves enclose the whitish leaves of the inner whorl. Often containing several yellow larvae. G. palustre: Dasineura hygrophila

39b More or less elongated, nearly egg-shaped, 2–6 mm long galls, consisting of 2–3 whorls of imbricate shortened, broadened, spoon-like bent leaves. Often also on tips of shortened side shoots. Larvae yellow. G. pumilum, uliginosum, etc.: Dasineura sp.

40a Malformations caused by gall mites => 51

40b Malformations caused by gall midges => 41

41a Gall consists largely of fleshy swollen parts of shoot axis, or leaf base => 49

41b Tufts of leaves lacking conspicuous fleshy thickenings; leaf blades sometimes only thickened at base or ± completely broadened => 42

42a Large, loose, bouquet-like leaf tufts, up to 15 mm long. Larvae jumping, yellowish-white or orange-coloured, or red => 48

42b Similar or smaller leaf tufts. Larvae non-jumping => 43

43a Up to about 2 mm long, ± unopened leaf rosettes on G. mollugo and G. verum => 47

43b Larger rosette-like tufts with ± erect leaves => 44

44a On G. boreale or G. sylvaticum, resp. saxatile => 46

44b On G. pumilum, mollugo, verum => 45

45a On G. mollugo. Tuft consisting of 4–6 whorls, outer leaves usually distinctly broadened over their entire length, the inner ones only slightly changed. Containing several pale orange larvae: Dasineura sp.

45b On G. verum. Soft, broadened at base of leaf blades, usually crimson-red discoloured leaf rosette: Dasineura sp.

45c On G. pumilum: Dasineura sp.

46a On G. boreale. Loose tuft of leaves on shoot tip, often also in leaf axils. Outer leaves egg-shaped-oblong, inner ones shortened, egg-shaped: Unidentified gall midge

46b On G. sylvaticum. Outer leaves of tuft little changed, inside ones imbricate, increasingly reduced: Unidentified gall midge

46c On G. saxatile. Up to 8 mm long terminal tuft of leaves: Unidentified gall midge

47a About 2 mm long, from the upper whorl shaped rosette consisting of several shortened, thickened, white to red discoloured leaves. G. verum: Dasineura sp.

47b Similar gall on G. mollugo: Unidentified gall midge

48a On G. mollugo; large loose tuft of leaves. Outer leaves little changed, ± discoloured at base and thickened, the inner ones progressively reducing and covering one another. Containing dirty yellowish-white larvae: Contarinia molluginis

48b On same host live in largely similar galls, occasionally together with larvae of previous midge, the red larvae of Contarinia acrocecis

48c On G. verum. Oblong bouquet-shaped, up to 15 mm long tuft consisting of shortened leaves, or inflorescence primordia. Containing orange-coloured larvae: Contarinia sp.

48d On G. lucidum. Leaves terminally clustered, tuft-like, on the stunted shoot tips, shortened, ± spoon-like, converging. Also including inflorescence primordia; together making a 10–15 mm long gall. Between the organs live several larvae. Contarinia galii

49a More or less fleshy galls on G. aparine => 50

49b Artichoke-like, up to 8 mm thick, half open gall terminally on main- and side shoot, also on generative shoots. Leaves obliquely erect, shortened, broadened at base mussel-like, fleshy or cartilaginous, sometimes ± reddened or violet-tinged, later on browned. Containing several orange-yellow larvae: Dasineura galiicola

= In many aspects similar gall, but only 2–4 mm long, emerging from mussel-like broadened but not fleshy thickened leaf blade base on G. boreale, mollugo, saxatile, pumilum, scabrum, verum. Might be induced by an unidentified gall midge

50a Tuft pineapple-like, large, dense. Shoot axis severely stunted, spongy, swollen. Leaves at base succulent, whitish, abnormally pubescent, occasionally some leaves in the complex develop normally. Containing pale sulphur-yellow larvae. G. aparine, spurium: Dasineura aparines and/ or Macrolabis jaapi

= Both gall midges may occur together, but M. jaapi may cause the death of D. aparines. The first-reported species is frequent; the last-reported species might be an inquiline of the cecidogenic Dasineura and is moderately frequent

50b Similar gall formation. However, leaves lacking pubescence at base. G. aparine: Unidentified gall midge

51a A rotund gall consisting of clustered, inward curved leaves develops on tip of main- and side shoots. G. palustre: Unidentified gall mite

51b Several leaves on shoot tip curled/folded, bent inwards and united into a loose gall. Cruciata laevipes: Unidentified gall mite

52a Usually only the leaves are disfigured and are often abnormally pubescent => 53

52b Apart from pubescence mainly on underside and ± folded and distorted leaves, large parts of flowering or non-flowering stems are also ± abnormally pubescent. G. boreale: Cecidophyes calvus

53a The additionally pubescent, disfigured leaves are almost only terminally on shoots => 55

53b The similarly galled leaves also occur on lower inserted whorls as well as on shoot tips => 54

54a Roll of leaf margin, both upwards and downwards, often associated with twisting and bending of leaf blade. Depending on host characteristics with ± protruding abnormal pubescence: Cecidophyes rouhollahi and/or Cecidophyes galii

= Until recently, this gall has been recorded as being caused by C. galii, however recently the mite has been determined as C. rouhollahi. Galls of both mites are identical, hence, the identity of all galls must be verified by an expert. Because Cecidophyes rouhollahi has only rather recently been described all records of “galii” are unreliable; all British material probably belongs to rouhollahi.

54b On G. scabrum. Leaf blade spoon-like arched, margin partially rolled upwards: Unidentified gall mite

55a On G. saxatile or G. verum => 56

55b On Cruciata laevipes. Margin of leaf blade completely deflected upwards or rolled inwards; ± short, whitish to brownish, abnormal pubescence on upperside: Cecidophyes psilocranus

56a On G. verum. At shoot tip clusters of several whorls bear reduced, yellowish leaves, densely pubescent with short, white hairs: Unidentified gall mite

= Swellings and distortions of leaves on G. verum are caused by Aculus anthobius

56b On G. saxatile. Leaves rolled, pale-yellow or reddish, ± strongly pubescent leaves form densely clustered, gall on shoot tip about 3 mm long: Unidentified gall mite

57a On inflorescences or single flowers => 58

57b Single or several ovaries usually including neighbouring parts of stalk transformed into a sessile, often purple discoloured, rotund to oblong-oval sometimes hunch-backed gall with ± spongy wall. The galls, about 1.5–5 mm long, are crowned with single or several, ± reduced or normally shaped and coloured, but not spreading corolla leaves. Inner wall lacking mycelium. Each ovary containing a saturated orange or coral-red larva. Galls may sometimes look similar to those of previous midge. A. cynanchica, G. glaucum: Dasineura asperulae

57c Similar galls on G. glaucum contain several, later on pale orange larvae: Geocrypta sp.

57d Fruit enlarged. G. mollugo: Undescribed gall midge

58a Large parts of inflorescence are disfigured, or also with greening and leafiness of flowers => 59

58b The buds of single flowers are swollen, especially at base, up to 3.5 mm long, wall thickened, outside violet coloured, inside lined with mycelium. Containing a single, or occasionally 2 or 3 yellowish larvae. Asperula and Galium spp., Cruciata glabra, Rubia peregrina: Schizomyia galiorum

= Trotteria galii lives as an inquiline in galls of Schizomyia. – Galls with Trotteria are smaller and do not contain healthy Schizomyia-larvae – Trotteria larvae are reddish

59a Primordia of inflorescence completely disfigured or large parts of inflorescence stunted, also additionally branched, usually with several to many flowers greened or leafy => 60

59b Instead of flowers or fruits, ± conical or acuminated, pear-shaped galls with fleshy walls develop up to 15 x 8 mm, outside pale-green, inside bearing many irregular protrusions. Asperula cynanchica, Galium spp.: Aceria galiobia

59c Axial parts of inflorescences ± shortened, sometimes excessively branched. Flowers ± leafy, organs bent, sometimes pale-green to reddish especially apically. Asperula cynanchica, tinctoria, Galium glaucum, odoratum: Aculus minutus

= From GB (Scotland) on G. saxatile have been recorded condensed and purple unopened flowers caused by the eriophyid mite Aceria informis.

60a Malformations caused by midge larvae or mite => 62

60b Malformations caused by aphids => 61

61a Inflorescence stalks ± stunted to varied extent; flower peduncles shortened, flowers variously leafy. Occasionally with excessive branching and leafiness. Asperula and Galium spp., Cruciata laevipes, Rubia tinctorum: Aphis galiiscabri

61b Shoots and flower stems become deformed and stunted by aphids feeding in ant-attended colonies close to ground. Galium austriacum, lucidum subsp. fruticescens, mollugo, verum: Hydaphias molluginis

62a Malformations include greening or leafiness of flowers => 64

62b Malformations lack greening of flowers, and also lack abnormal pubescence => 63

63a Flower buds small, yellowish discoloured, unopened. In clusters on only slightly stunted shoots. G. verum: Unidentified gall mite

63b Primordia of inflorescence densely clustered, ball-like; transformed into a ± acute- or blunt conical gall, up to 10 (12) x 15 (20) mm, bearing lateral branchings and many small leaf tips at surface. Many red, jumping midge larvae live between organs. G. mollugo, verum: Contarinia acrocecis

= On G. mollugo in such galls occasionally live, together with the red acrocecis-larvae, the white larvae of Contarinia molluginis

64a Leafiness or greening without abnormal thickening of respective organs => 65

64b Flowers on stunted and ± excessively branched axial parts transformed into dense bunches of small, rolled, ± thickened leaves. G. palustre: Unidentified gall mite

65a Leafiness of ± clustered flowers on Cruciata laevipes, Galium pumilum, scabrum, sylvaticum: Unidentified gall mite

65b On many other Galium species a rosette of small leaves occurs instead of flowers, which are often ± clustered, ball-like, due to shortening of stalk: Aculus anthobius

= Tegoprionus dentatus, occasionally reported as gall causer on Galium, might be inquilinous in galls of Aceria galiobia, Aculus anthobius

gallers on Artemisia

pub 13.xi.2019

Dichotomous table for gallers on Artemisia

by Hans Roskam

1a On above-ground part => 2

1b Roots with nodules, a few mm long swellings, lacking a larval chamber, exhibiting adventitious roots, A. maritima: Meloidogyne hapla

= Similar smooth root galls are known from many countries on other Artemisia species; from which several Meloidogyne species have been determined as causers

2a Malformations of inflorescences and of capitula => 41

2b Malformations of vegetative parts, sometimes encroaching into the inflorescences => 3

3a Rosette- or bud-like, largely closed malformations of rather distinctive shape on shoot tips or lateral buds => 37

3b Plant extensively malformed over various parts, loose malformations of shoot tips or galls on shoot stems and leaves => 4

4a The malformations mainly on the shoot stem or root collar => 23

4b Shoot with extensive malformations, or galls on leaves => 5

5a Leaves with ± defined galls => 12

5b Malformation of the whole plant or many leaves; at the end of the shoots respectively tuft-like clumps of mostly only insignificantly deformed leaves => 6

6a Leaves malformed, at the top of severely stunted shoots ± tuft-like stacked => 11

6b Malformation of many leaves on partially or extensively, stunted stems, however not only stunted at the top => 7

7a Malformations on several or many leaves, at the top of ± shortened shoots; leaves close together; caused by aphids or cercopids => 8

7b The whole plant sometimes with the shoots extensively malformed; all affected parts discoloured. Internodes elongated, often curved. Leaves smaller, malformed, rolled downwards at the margins, bent and twisted; capitula, if present, stunted, deformed, often with ± shortened stems. Extensive branching and phyllanthy. A. campestris, vulgaris: Aceria subtilis

7c Similar malformations of A. vulgaris, displaying also phyllanthy, might be attributed to: Aceria horrida

7d Leaves are disfigured and turn reddish-violet. Artemisia spp.:Aceria tingens

= The gall mite Paraphytoptus paradoxus causes erinea on leaves of A. absinthium

= The gall mite Aceria absinthii causes malformations on leaves and flower heads of A. absinthium

8a Malformations caused by aphids => 9

8b Younger leaves, still growing close to the ground are locally stacked, bent; the closely positioned leaves are ± clump-like converging; locally conspicuously curved and dark green. Containing froth-covered nymph: Philaenus spumarius

9a Leaves slightly rolled inwards or curled, ± stacked => 10

9b Shoots stunted in longitudinal growth. Several leaves in different ways blister-like swollen, rolled together and curled, often very close, stunted, pale green or remarkably reddish. Aphid exuding wax. A. vulgaris: Cryptosiphum artemisiae

9c On A. campestris in similar malformations lives Cryptosiphum brevipilosum

10a Leaf development stunted, yellow spotted or pale green; stacked on the shortened internodes, sometimes in dense clusters; aphid green:

a A. absinthium, vulgaris: Coloradoa artemisiae

c A. campestris in similar malformations: Coloradoa campestrella

c Malformed leaves on A. vulgaris: Macrosiphoniella artemisiae

10b Leaves on the shoot tips similarly malformed, curled, margins ± downwardly bent. A. absinthium: Macrosiphoniella absinthii

11a Shoot tips with small, open tufts of a few folded ± twisted and curled leaves. Containing several bright red larvae. A. vulgaris: Unidentified gall midge

11b Leaves on shoot tips tuft-like stacked, shortened and including the broadened petioles. A. vulgaris: Tingis crispata

11c Terminal parts distorted. A. herba-alba, valentina: Xerobion blascoi

12a Malformations of mainly constant shape of leaf margins and on leaf blades => 13

12b Basal leaves of young plants severely stunted, petioles and basal parts of leaves spongy, inflated, pale green; soon withering. A. campestris: Ditylenchus dipsaci

13a Galls on leaf blade or in venation => 16

13b Malformations of leaf margins or the slender leaf tips => 14

14a Leaf tips or margins locally reverted, discoloured, or often conspicuously reddened. Aphid galls => 15

14b Margin of usually many leaves situated close to the shoot tip, often tightly downwardly rolled over different lengths. A. vulgaris: Aceria marginemvolvens

14c Prominent pustules terminally on both sides of tips of leaf segments; these are sometimes slightly enlarged. A. arborescens: Aceria affinis

15a Leaf tips downwardly rolled; leaf blade bulge-like swollen. Galls usually strongly reddened. A. absinthium, dracunculus, vulgaris: Cryptosiphum artemisiae

15b Leaf tips, also rachis, at the suction sites thickened, yellow green or violet-red coloured; often angular or crooked. A. campestris: Cryptosiphum brevipilosum

16a Galls small, up to ± 1.5 mm long, pock-, nodule-shaped or globular, induced by gall mites => 19

16b Galls larger, about 2 mm long or bigger, midge galls => 17

17a Galls predominantly developed on one side of the leaf blade, slender => 18

17b Galls 2–5 mm long, berry-like, on both sides of the leaf blade distinct. A. campestris incl. subsp. maritima, scoparia: Rhopalomyia baccarum

18a Galls protruding on upper side, about 2 mm long, oblong egg-shaped, acuminate, yellowish or reddish, at top with narrow opening, unilocular; thin-walled, ± transparent; solitary or gregarious; usually on veins. A. abrotanum, vulgaris: Rhopalomyia foliorum

18b Similar galls on A. campestris: Rhopalomyia pseudofoliorum

18c Small ellipsoid galls on leaf axils, leaf blade and rachis, clustered. A. pontica: Rhopalomyia baudysi

18d Galls similar, slightly larger, more acute-cone-shaped, yellowish green or ± reddish, outside strongly pubescent; preferentially on the base of ± stunted leaflets; sometimes on the leaf underside, also in the inflorescence. A. absinthium, genipi, pontica: Rhopalomyia luetkemuelleri

18e Small gall at the vegetative tip with several chambers inside. A. campestris: Rhopalomyia simulans

18f Large globular galls containing midge larvae. A. austriaca: Rhopalomyia saissanica

19a Galls pock- or nodule-shaped, with broad base, less than 1 mm high => 20

19b Galls pimple-shaped, on the leaf upperside, usually many per leaf blade, 1–2 mm long, at the base ± narrowed, often reddened. Opening on the underside, surrounded by hairs. A. eriantha, pontica, vulgaris: Aceria artemisiae

20a Galls flat pimples, glabrous, somewhat protruding, globular or oblong, pale green in the beginning, browned later on; sometimes on petioles or stems => 22

20b Galls nodule-shaped, usually densely whitish pubescent => 21

21a On A. pontica, vulgaris: Aceria pontica

21b On A. austriaca, campestris: Unidentified gall mite

22a On A. absinthium, ? austriaca: Phyllocoptes tenuirostris

22b On A. campestris, vulgaris: Unidentified gall mite

23a Swellings of apical stem parts => 28

23b Galls on root collar or close to the ground => 24

24a Galls several cm long, close to the ground => 26

24b Galls ± globular, close to root collar => 25

25a Swellings of root collar, emerging from a bud; scales ± preserved, ± enclosing a tough-walled gall. One larva inside with black mandibles; or a puparium. A. campestris, scoparia: Napomyza annulipes

25b Buds of stem base developed into ± globular. 4–6 mm long, berry-like, succulent, pale green or reddened galls; occurring solitarily or gregariously. One orange-coloured larva per gall. A. campestris, vulgaris, etc.: Rhopalomyia baccarum

25c Large stem gall, up to 20 mm across, densely white haired, on last year’s stem. Artemisia spp.: Rhopalomyia sp.

26a On A. campestris, maritima => 27

26b On A. vulgaris. Root collar and adjacent stem parts swollen. Containing a single white caterpillar with brown head capsule: Epiblema foenella

27a On A. campestris. Stems usually distinctly swollen at their base; the distal longitudinal growth stunted or completely prevented. Galls up to 60 mm long, 10–12 mm wide; partially concealed in the soil. Containing a single whitish caterpillar with bright- to dark brown head capsule: Cochylimorpha hilarana

= Also reared from more basally situated stem galls on A. maritima

27b Smaller swelling on young twigs. Galls only up to 30 mm long, 3–4 mm wide.A campestris incl. subsp. glutinosa, maritima: Cochylimorpha pontana

27c Spindle-shaped swelling on the stem, development of which is completely stunted, an ovoid gall, 12–13 x 7–8 mm, occupying soon the tip, soon the middle; with a terminal exit hole for the straw-yellow caterpillar. A. campestris incl. subsp. maritima: Cochylimorpha halophilana

27d On A. barrelieri, campestris: Cochylimorpha cultana

27e On A. maritima. Galls also partially in the upper part of the stem, spindle-shaped, up to 20 mm long and 5 mm wide. Containing a single yellowish-white caterpillar: Eucosma krygeri

28a Galls embracing stem, conspicuous, oblong-oval or ± clearly spindle-, tube- or cylinder-shaped, with one- to several larvae inside => 29

28b Cortex of stem with rotund or oblong, sometimes ± coalescing, later on bright brown, pock-like swellings. Infestation sometimes extending to the petiole and leaf blade. A. absinthium, austriaca, campestris, vulgaris: Unidentified gall mite

29a Larvae with distinct head capsule => 32

29b arvae without distinct head capsule => 30

30a Maggots cylindrical, with distinct black mandibles, pupating at feeding site => 31

30b Larvae without mandibles, with sternal spatula. Stem locally stunted, with 10–15 mm long, tube-shaped, abnormally pubescent swelling; leaves stacked. Containing a single orange-yellow larva. A. campestris: ? Rhopalomyia sp.

30c Main shoot with large oblong spindle-shaped, one-chambered swelling, about 20–50 mm long and 15–20 mm thick, initially green and succulent, later brown and woody, inside with a black mass of mycelium. Up to 100 larvae per gall. A. vulgaris: Lasioptera artemisiae

31a Stem with tough, nut-like swelling, up to 15 mm long. A. campestris: Oxyna parietina

31b Upper part of stem stunted, curved and twisted. Pith with several larvae. A. vulgaris: Oedaspis multifasciata

32a Galls more than 10 mm long, containing usually coloured butterfly caterpillars; Head capsule about equal to body width. Shoot growth above the galls usually severely stunted => 33

32b Up to 6 mm long and 3 mm thick acuminated, round-oval, unilocular swellings. Shoot longitudinal growth not stunted. Containing a single larva; head capsule narrower than body width. A. campestris: Taphrotopium sulcifrons

33a Tough, oblong galls on the shoot tips of A. campestris, dracunculus, maritima => 35

33b Extended galls on A. absinthium, vulgaris => 34

34a The higher parts of the shoot stem of A. absinthium, vulgaris stunted; spindle-shaped galls containing thick, yellowish-white caterpillars with a brown head capsule: Eucosma metzneriana

34b Stem of A. vulgaris in the middle part with spindle-shaped swelling, up to ± 40 mm long, 6 mm thick. A yellowish-grey, dark-headed caterpillar in pith canal extending over a considerable distance. Unidentified lepidopteran

35a Caterpillars yellowish to reddish => 36

35b Caterpillar yellowish-white, sometimes tinged pink, with bright- to dark brown head capsule. A. campestris: Eucosma albidulana

36a Caterpillar yellowish or reddish, with dark brown head. A. campestris: Eucosma lacteana

36b Caterpillar yellowish or reddish-yellow with brown-black head. A. campestris, dracunculus: Eucosma wimmerana

37a Galls on the shoot tips of severely stunted stem => 39

37b Bud galls => 38

38a Unilocular, ± rotund, up to 6 mm long, pale green, berry-like succulent bud gall; solitary or with several in the leaf axils, mostly on the lower part of the shoots. One orange-coloured larva per chamber. A. vulgaris, more rarely A. campestris, scoparia: Rhopalomyia baccarum

38b Ovoid swelling covered by leaves. A. herba-alba: Rhopalomyia hispanica

38c Globular woolly gall. A. herba-alba, incana, judaica: Rhopalomyia navasi

38d Development of ovoid acuminate galls at the cost of shoots or leaves, 5–6 mm high, 2 mm wide, glabrous, slightly succulent, tough, becoming at maturity a little woody, red or brown. Contains an initially yellow, later on red larva. A. alba: Rhopalomyia kiefferi

38e Terminal cluster of disfigured and oval leaves, bud-like, enclosing a little ovoid larval chamber. Contains a single larva. A. campestris incl. subsp. variabilis, scoparia, vulgaris: Rhopalomyia artemisiae

38f Lateral buds changed into rotund, rather tough walled, dark coloured galls about 3 mm long. Galls situated at different height on the stem, mainly in the lower part. A. vulgaris: ? Rhopalomyia sp.

= The tephritid Ptiloedaspis tavaresiana may cause bud galls on A. herba-alba.

39a Leaves in tufts; gall chambers invisible from the outside => 40

39b Shoot tip with several close, cylindrical-cone-shaped galls, up to 15 mm long, tough walled, ± violet, white pubescent. Opening at the tip, closed by hairs, encircled by spreading, pubescent teeth. Containing a single white larva per chamber: A. campestris incl. subsp. glutinosa: Rhopalomyia tubifex

39c Shoot tips, with several small, rotund to oblong-oval, bold galls. Containing a single larva per gall. A. pontica: Rhopalomyia baudysi

39d Small galls of various form on leaves, leaf stalks and stems. Each gall containing a single red midge larva. A. arborescens: Rhopalomyia protrahenda

40a Apex of main- and lateral shoots with ± ovate or almost globular, bud-like closed tufts. Leaf segments shortened and broadened. Galls in the lower part sometimes with ± silk-like pubescence; the inside with several small, oblong chambers, open at the apex, with translucent wall. Galls with only a central chamber about 3–4 mm long, if multilocular up to 15 mm wide; often overgrown by lateral stalks of the inflorescence. Containing a single larva per chamber. A. campestris, scoparia: Rhopalomyia artemisiae

40b From small, similar globular shoot tip galls is also described Rhopalomyia campestris

40c Leaves at the shoot tips in tufts and abnormally pubescent. One orange-coloured, glossy larva. A. austriaca, campestris, scoparia: Unidentified gall midge

= Abnormally pubescent stunted shoot tips or lateral buds on A. campestris are caused by the gall midge Rhopalomyia jaapi.

40d Tuft terminally on shoot, composed of young branches and curled leaves. A. arborescens, campestris, vulgaris: Aceria subtilis

41a Malformations of capitula caused by gall midge- or tephritid larvae => 45

41b Malformations of capitula or inflorescences by gall mites => 42

42a Malformation of capitula not in abnormally shortened inflorescences => 43

42b Capitula of the severely stunted inflorescences concentrated in thick, spike-shaped clumps, often purple-red coloured. A. vulgaris: Unidentified gall mite

43a Capitula enlarged, rotund; florets ± tongue-shaped deformed, greenish => 44

43b Involucre of the flower head distinctly elongated, twisted at the top. Flowers aborted. A. campestris: Unidentified gall mite

43c Subglobose malformations on the flowers which are normally shaped further on, but are reddish coloured. A. alba: Aceria artemisiae

44a Galls on A. campestris: Aceria subtilis

44b Similar galls on A. vulgaris: Aceria horrida

45a Galls caused by slender midge larvae lacking conspicuous mandibles => 47

45b Receptacle swollen, ± hardened. Containing a single yellowish-white, cylindrical larva with distinct mandibles. A. absinthium: Trupanea stellata

45c Flower head swollen. A. campestris subsp. maritima: Tephritis dioscurea

45d Flower head swollen. A. vulgaris: Campiglossa absinthii

46a Galls on A. campestris, genipi => 49

46b Galls on A. vulgaris => 47

46c Galls on A. herba-alba. Cylindrical gall, 9 x 3 mm, wall finely pubescent and covered with many bracts; inside an oblong large chamber which is closed by a tuft of white hairs and a crown of bracts. Containing a single orange larva: Rhopalomyia producticeps

46d Galls on A. herba-alba. Axillary buds changed into small galls, 6 x 4 mm in size, each gall is composed of many very small leaves, inside a chamber with one larva. Usually many galls occur on one attacked stem: Rhopalomyia ambrosinae

46e Large galls on stems. Globular galls, up to 10 mm, densely white pubescent, situated on stem sides; several chambers occur inside one gall. Only one larva in each gall. Galls may coalesce in large forms, up to 40 mm. A. herba-alba: Rhopalomyia navasi

46f Small galls on stems. Swollen buds, egg-shaped, fleshy, reddish coloured, surrounded with deformed leaves, with a small ovoid gall in its centre. A. herba-alba: Rhopalomyia hispanica

47a Capitula enlarged, ovate or blunt slender conical => 48

47b Capitula ± globular; one large central gall. Containing a single deep yellow larva. Anthodiplosis rudimentalis

= The midge larvae of Blastodiplosis artemisiae, living in the galls, should be considered either as inquilines or as parasitoids of Anthodiplosis

48a Capitula weakly thickened, containing yellow, jumping larvae: Contarinia artemisiae

48b Capitula slightly enlarged and elongated, truncated at the top, ± red-coloured. Between the flowers an ovate, translucent gall containing a single larva: Rhopalomyia florum

48c Also from weakly thickened capitula have been recorded: Rhopalomyia magnusi

49a On A. campestris => 50

49b On A. genipi. Inflorescence often shortened. Small, ± acuminate ovate, at the outside pubescent, tough-walled galls on involucral bracts, also in deformed flowers. Containing a single larva: Rhopalomyia luetkemuelleri

50a Malformation of single, or several adjacent, capitula without externally recognisable gall chambers => 51

50b Capitula extensively changed into a consistent large gall ± cylindrical, up to 12 (15) mm long, with some green leaflets on the outer side. Wall of gall firm, ± violet-white pubescent, with extending leaf-like teeth at the top; entry closed by hairs. Containing a single white larva: Rhopalomyia tubifex

51a Capitula extensively reshaped, rounded, bud-like, consisting of ± ovate leaflets, which enclose an oblong, translucent walled gall body. In very compressed shoots several gall bodies sometimes appear superficially to be unified. Containing a single larva per gall: Rhopalomyia artemisiae

51b From similar galls in shoots and capitula have been recorded: Rhopalomyia campestris

51c Capitula weakly swollen; containing orange-yellow larvae between stunted organs: Dasineura artemisiae

= The non-cecidogenic Puccinia tanaceti with uredinia and telia is abundant on the underside of the leaves.

gallers on Quercus

pub 6.xi.2019

Dichotomous table for gallers on Qercus

by Hans Roskam

AG: agamic generation of gall wasps; SG ditto, sexual generation; ?G: generation unknown.
Galls on different plant parts have been subdivided in different keys:

Deciduous oaks
(Quercus robur, Q. petraea, Q. pubescens; with reference to Q. frainetto and galls occurring occasionally on exotic oaks)

Deciduous oaks, on roots

1a Galls ± rotund, about pea-size or much larger, larval chambers inside => 2

1b Galls smaller, nodular or elongated spindle-shaped, without chambers: Meloidogyne sp.

2a Single galls ± globular; pea-, more rarely cherry-size up to 8 mm across, one-chambered; initially whitish-reddish to red-brown, glabrous, succulent, later woody, black-brown and rough on the outside. Usually on the filamentous roots down to 50 cm and deeper underground. Often in a bunch of grape-like or bulb-clustered groups, up to 30 mm across, mutually flattened or more rarely ± coalescing. Gall containing one larva per chamber. Q. petraea, pubescens, robur, pyrenaica, lusitanica: Biorhiza pallida AG

2b Galls much larger; irregular rotund or oval, ± crenate, up to 70 (80) mm across, many small chambers; initially succulent, later woody, with flaked cortex. On thicker roots close to the surface, more rarely at stem base. Containing one larva per chamber. “Truffle gall”. Q. petraea, pubescens, robur, lusitanica and some close allies. Andricus quercusradicis AG

= Inquiline gall wasps: Saphonecrus connatus and Synergus apicalis.

Deciduous oaks, on stems, branches, twigs or shoots
(For galls developing from latent buds on stems, often directly on the bark, see Section C)

1a Inducers completely or partially on the outside of the galls => 18

1b Inducers inside the galls => 2

2a On old oaks => 3

2b Predominantly on seedlings. The caterpillar mines in the cortex, and damaged tissue regenerates with diffuse proliferations, causing curving of the seedlings. Q. petraea, pubescens, robur:Spulerina simploniella

3a Swellings on shoots of current or the preceding year => 8

3b Variously shaped malformation erupting from the bark on perennial twigs or stems, more rarely on old stems or on coppice; often hidden in herb layer, more rarely in the soil => 4

4a Single galls rotund or cone-shaped, about pea size or up to 1 cm across; basal part hidden in bark => 6

4b Galls about cherry- to fist size => 5

4c Midge larvae cause necrosis of cambium and bark- or timber damage to trunks of young oak trees and upper branches of older trees. Q. petraea, robur: Resseliella quercivora

5a Galls rotund or ± oval, walnut- to chicken egg size, multi-chambered. At the base of perennial stems, often in the soil. Q. petraea, pubescens, robur, etc.: Andricus quercusradicis AG

5b Partially fissured, later woody massive tumours of often considerable size have also been found on younger stems of Q. petraea. Probably partially caused by bacteria, although in many cases these have not been verified: Agrobacterium tumefaciens

= The small to expanded “wood crops”, cancers, occurring on perennial branches are not true galls; the causes may be various.

6a Mature galls cone-shaped to cylindrical => 7

6b Mature galls ± semi-globular, 2–6 x 3–5 mm, single or some galls clustered, protruding from the bulging bark. When young, with red fleshy wall, later brown, woody, at the base with longitudinal ridges. At top with emergence hole. Containing a single larva per gall. Q. petraea, pyrenaica, robur, lusitanica, etc.: Andricus rhyzomae AG

6c An extremely cryptic gall induced beneath the bark of branches and shoots; monolocular, often aggregated. The small larval chambers are induced just beneath the bark, without any visible external deformation of the shoot. The galls are most easily located by the emergence holes made by the adults. Q. robur, petraea, pubescens: Callirhytis erythrocephala SG

7a Galls developing deep in the woody tissue; outer half upwardly narrowed, wide cone- or ± pear-shaped, initially reddish, soft; later, after losing its outer envelope, brown, hard. Gall wall, compared with the large larval chamber relatively thin; in dry condition ridged from base to top with lateral emergence hole. Often protruding from rather swollen stem, ± covering thinner parts on all sides. One larva per gall. “Barnacle gall”. Q. petraea, robur, pyrenaica, lusitanica, etc.: Andricus testaceipes AG

7b Gall initially slender egg-shaped, ± acuminate, white or reddish, 6–10 mm long, about 4 mm across; with socket part sunk into otherwise damaged old stems or branches; single or more often in dense clusters and mutually flattened to ± three-sided pyramids. Before maturity covered by fleshy semi-globular to oval, yellow-green or –reddish, 3–4 mm long lid, drying out later on and dropping. The remaining cup-shaped part woody, protruding from the stem as a short cylindrical stub. Larval chamber separated by a thin hard, arched scale; the ± circular rim with deep pits (remains of vascular bundle). Containing a single larva per gall. Q. petraea, pubescens, pyrenaica, robur, lusitanica, etc.: Andricus quercuscorticis AG

7c Similar gall, differs by a ± cylindrical funnel which leads to the larval chamber: Andricus quercuscorticis AG

7d Gall shallowly embedded in the bark. Galls found on bark crevices, sometimes close to the ground; on branches 2‒5 years old buried in leaves and covered with moss; on regrowth shoots; in the axils of suckers around stumps. Rarely singly, generally in dense aggregations of galls at different stages of development. Galls conical in shape and found in tight groups, pea-sized with a grooved surface and a pear-shaped apex. Gall outer wall is reddish purple and fleshy, and is cast off as the gall develops. The wall of the gall beneath is initially whitish and soft-structured, hardening later and becoming brown, longitudinally grooved from the tip. Exit hole at the side. The galls can be confused with those induced in a similar location by the agamic generations of A. quercuscorticis and A. rhyzomae. A. quercuscorticis galls are frequently smoothly rounded and paler, and lack radiating grooves on the gall surface. Galls of A. sieboldi project further from the stem than those of A. rhyzomae, and the emergence hole is often in the side of the gall rather than at the summit as in A. rhyzomae. Galls of A. sieboldi also more frequently retain a cap of the external gall tissue usually shed in A. quercuscorticis and A. rhyzomae. Q. robur, petraea, pubescens, macranthera, iberica, lusitanica, pyrenaica: Andricus sieboldi AG

8a Small, 2–3 mm long, nodular swellings, partially protruding from the cortex => 16

8b Often expanded swelling of the shoot, on either the tip or sometimes on lower parts of young shoot => 9

9a Galls distinct from the exterior => 10

9b Shoots externally hardly changed. A terminal gall at maturity with a hardly distinct emergence hole may be found between the densely clustered lateral buds at shoot end are on the sometimes stunted shoots. Containing a single larva: Andricus turionum AG

10a Galls spindle-shaped, elongated or curved and crooked => 12

10b Swellings plump club-shaped, directly situated on the distinctly stunted top. Leaves clustered, leaf blades developed normally => 11

11a Galls at tip of twig, 15 (20) x 8 (10) mm. Centrally with longitudinal narrow cavity, eventually open above; at its base a small, oval, only terminally free inner gall. A single larva. Q. petraea, pubescens, robur, rubra, rubra var. maxima, lusitanica: Andricus inflator SG

11b Galls similar but smaller, only 6 mm long and 5 mm across. One larva. Q. pubescens, robur, pyrenaica, lusitanica, etc.: Andricus pseudoinflator SG

12a Galls not conspicuously curved => 13

12b Young shoots angularly curved, sometimes strongly deflected. Inside the stunted, thickened knee a pea-size swelling, sometimes 2–3 mutually coalesced, cartilaginous, green, initially succulent, each hiding an inner gall. Each containing one larva. All deciduous oaks: Andricus curvator SG

13a Development of galls in first year shoots => 14

13b Larvae in terminal part of previous year shoots which are swollen at the site of infestation; upward parts diseased and withering early. A single larva in pith. Q. petraea, pubescens, robur: Janus femoratus

14a Larvae in pith => 15

14b Stems with tubercular spindle-shaped swellings, pervaded by a screw-like ascending tunnel, which in cross-sections may be gall-like swollen by callus-proliferations. Larvae between sapwood and cortex. All deciduous oaks: Agrilus biguttatus

15a Shoot at tip almost evenly 2- to 3-fold swollen over a length up to 6 cm. In pith a white caterpillar with bright chestnut brown head. Q. petraea, pubescens, robur: Stenolechia gemmella

15b In similar galls on same oak species: Epinotia festivana

15c Spindle-shaped gall, 2 mm long, emerging from a slit in the bark of a young twig. Q. petraea, robur: Pseudoneuroterus saliens AG

15d Large subglobular gall embracing the twig. Q. petraea, robur, pubescens: Aphelonyx cerricola AG

16a Galls on scars of bud scales or outside the buds in the leaf axils => 17

16b Galls usually with several on nodes, also on internodes, often at the base of one-year, ± shortened and locally thickened shoots. Solitary galls in bark, often hard to find, flat, often very slight spindle-shaped, up to 2 mm large, with a hardly 1 mm large internal gall. Chambers inside twigs have flat, circular rims, best seen if bark removed. Q. petraea, pubescens, robur, cerris, etc.: Andricus quercusradicis SG

16c Similar, but usually solitary galls. Q. petraea, robur. GW: Andricus testaceipes SG

16d Similar, inconspicuous, slightly arched cortex galls on young twigs. Q. petraea: Plagiotrochus marianii AG

= Three other cynipid species (Callirhytis glandium SG, C. rufescens SG and C. hartigi SG) cause similar galls in twigs and young shoots on Q. robur. There is no external sign of these galls

= The oak bark phylloxera Moritziella corticalis causes cancerous bark on the previous year’s growth. Known at a few localities in S- and E-England since 1972.

17a Galls with broad base attached on the scars of bud scales at the base of just extending shoots; oblong-oval, up to 1.5 mm thick and 2–3 mm long, white-yellow to bright brown. Containing a single larva. All deciduous oaks: Neuroterus anthracinus SG

17b Galls two- or three together, on young shoots, often close to axils of just extending leaves; attached with narrow base, elliptical, 1–2 mm long, initially green, later brown, bold, glabrous, very thin-walled. Containing a single larva. Q. petraea, pubescens, robur, cerris, lusitanica, etc.: Andricus quercuscorticis SG

18a Galls in the still glabrous bark of young stems and twigs => 21

18b Malformations usually on older organs, already developing bark => 19

19a Branches with conspicuous malformations, developing mistletoe => 20

19b Coppiced stem parts with open proliferations with bulging rims. “Nectria-cancer” Q. petraea, robur, etc.: Neonectria ditissima

19c Cancer-like rimmed malformations on young twigs, still lacking bark: Caudospora taleola

20a Affected twigs locally swollen; base of mistletoe stem dome-shaped margined. Mistletoe deciduous. Q. cerris, petraea, pubescens, robur, etc.: Loranthus europaeus

20b Local, often conspicuous swelling of twig; typical “rose-formation” absent. Mistletoe evergreen. Q. petraea, pubescens, robur: Viscum album

= Similar witches’ brooms have sporadically been recorded from endemic oaks, and, on various occasions, on red oaks. The cause is unknown, parasites have not been found.

21a Bark of the thinner twigs usually of younger plants with smaller, oval, flat-grooved, bulging-rimmed depressions, harbouring a scale insect => 22

21b Bark of the two-year old and perennial twigs, usually on the underside with expanded, 2–3 mm thick, later with longitudinal fissures bursting proliferations of the cambium. Q. petraea, pubescens, robur: Lachnus pallipes

22a Insects with flat scale => 23

22b Scale usually rotund-oval, about 1.5 x 2 mm across, ± strongly convex, greenish, brownish or yellowish. Scales in various densities usually keeping some distance apart, many in profile on the ± disfigured young shoots. On many oaks, predominantly on Q. robur: Asterodiaspis variolosa

22c Similar lifestyle, apparently more sparse: Asterodiaspis minor and/ or A. quercicola

23a Similar depressions, often more irregular. Scale insect with pear-shaped, whitish to grey-white shield, about 2.5–3 mm long. Females wine-red. All deciduous oaks: Chionaspis salicis

23b Malformations similar to above. Rim often less distinct. Shield of the females rotund, about 3.5 mm long, dark. Females vivid yellow. Q. petraea, pubescens, robur, etc.: Diaspidiotus zonatus

23c Stunting and branching of young shoots. Q. robur: Parthenolecanium rufulum

Deciduous oaks, on buds or on ± extending terminal shoots

1a Buds unopened, only slightly changed externally or completely to partially transformed into often conspicuous closed galls of various shape => 3

1b Galls on shoot tips => 2

2a Shoot axis distinctly stunted, club-like, swollen. Gall up to 15 (20) x 8 (10) mm, bearing clustered, mostly normal leaves. Galls centrally with a narrow, cylindrical, soon apically opening cavity; at base with an oval sessile inner gall. Containing a single larva: Andricus inflator SG

2b Buds on extended and ± stunted shoots. Young leaves clustered almost ± artichoke-like. Their leaf blades, only 10–30 mm long, folded upwards, irregularly twisted and curled. Veins, especially midrib, ± thickened and sometimes haired. Several yellowish-white jumping larvae. Q. petraea, robur, etc.: Contarinia quercina

2c In similar malformations, whitish larvae also gregarious, non-jumping: Arnoldiola quercus

2d Larvae bright orange to reddish yellow: Dasineura dryophila

3a Buds completely or partially transformed into particular, distinctly recognizable, small to sizeable galls => 5

3b Buds unchanged externally or only slightly transformed => 4

4a Buds slightly enlarged, not opening. Containing usually several red larvae. Q. faginea, petraea, robur, ? pubescens, lusitanica: Arnoldiola quercus

4b An egg-shaped gall completely covered by scales, up to 2 mm long, inside an externally hardly transformed bud. Eventual exit hole laterally. Containing a single larva. Q. petraea, pubescens: Callirhytis bella SG

5a Galls develop in terminal- or lateral buds on young, one- or also two-year, especially lateral, free-standing shoots => 17

5b Galls arise on thin- or thicker perennial, usually basal, shoots or older stems, here on latent buds => 6

6a Gall body with lateral enlargements, sometimes with spines or with thread-, club-shaped or conical appendages => 10

6b Shape of gall body uniform; surface glabrous or pubescent => 7

7a Galls about 3–5 mm long, slender egg-shaped or cylindrical => 8/p>

7b Galls rotund, usually short acuminate, pea-, exceptionally up to cherry-size, ± whitish or on above-ground parts often shining coral-red, cowberry-like, glabrous or with some brown scales; thick-walled, succulent, one-chambered. Separate or in groups. Each containing a single larva. Q. petraea, pubescens, robur: Trigonaspis megaptera SG

8a Galls up to 3 mm long; on Q. petraea, robur => 9

8b Galls on Q. pubescens, pyrenaica, 3–5 mm long, egg-shaped, greenish or reddish, surface densely covered with small hairs, usually red distally; thin-walled, soft, one-chambered, covered by bud scales at base. Containing a single larva: Cynips quercus SG

9a Galls slender egg-shaped, 2–3 mm long, rotund on top or slightly depressed. Initially red, later dark-violet, densely velvet-like pubescent, thin-walled. At base with bud scales. A large chamber containing a single larva. Q. petraea, pubescens, robur, cerris: Cynips quercusfolii SG

9b Gall similar, 4 mm high, 2 mm in diameter, terminally rounded, brownish when mature, glabrous or very finely pubescent. Usually several galls are clustered, but not coalesced. Q. petraea: Biorhiza cecconiana AG

9c Gall similar, but grey-green or grey-brown, smaller, only about 2 mm long; slender egg-shaped, ± acuminate. Hairs slightly longer, whitish; bud scales absent at base, thin-walled. A large chamber containing a single larva. Q. petraea, robur, lusitanica: Cynips longiventris SG

10a Appendages on the entire gall surface => 12

10b Appendages limited to parts of the gall => 11

11a Appendages on the basal half of the gall, very irregular, short and thick, like an uneven humped bulge closely appressed to the shoot axis; upper gall half obtusely conical, with rounded end. Gall 10–12 mm long, with same width at base. Surface net-like checkered, brown, with white stellate hairs or almost glabrous. Outer wall spongy, chamber in the under part, large; protective layer woody. Containing a single larva. Q. petraea, pubescens, robur, frainetto: Andricus conificus AG

11b Gall consists of two parts; distal parts is 7‒8 mm high, 5‒6 mm wide, brownish, almost woody, cup-shaped opened and separated by a narrow circular groove from the distal part which envelopes the twig, but is only narrowly attached. Basal part of gall pubescent; gall chamber rotund, thin-walled, situated in basal part of gall. Q. pubescens: Andricus korlevici ?G

11c Galls with a sharp-edged, ± undulate shallowly lobed corolla, urn- or bell-shaped, 6–9 mm high, yellowish-green, reddish or bluish. Outer wall a little tough; inner wall hard. Containing a single larva. Q. petraea, pubescens, robur: Andricus polycerus AG

12a Appendages ± filamentous, at least terminally setose or conspicuously pubescent => 16

12b Appendages more rough, sometimes terminally slightly haired, but without setae => 13

13a Protrusions not contacting one another, obtusely conical or papillate, sometimes spine-like or also comb- to ridge-like => 15

13b Protrusions enlarged in middle- or upper part, hence touching one another => 14

14a Appendages initially stalk-like, then suddenly pyramidally enlarged and closely touching, covering the actual gall body. Gall body one-chambered, globular, about pea-size, including protrusions, walnut-size. Containing a single larva. Q. petraea, pubescens, robur, frainetto, pyrenaica, etc.: Andricus hartigi AG

14b Appendages stalked, terminally disc-like enlarged, covering completely the woody gall body, like a tortoise shell. Shields of the under half three- to four-angular, of about equal size on all sides; on the upper half converging like long equal-sided triangles. Galls one-chambered, incl. appendages, about pea-size. A single larva. Q. petraea, pubescens, robur, lusitanica, etc.: Andricus truncicola AG

15a Galls sessile, 3–4 mm across, rotund, with many sturdy papillae or conical tubercles, increasing abruptly from base to top, terminally rounded, often red, with fleshy outer layer, later yellowish or brown and woody. In the basal part is a wide- oval inner gall containing a single larva. Q. petraea, pubescens, robur, etc.: Andricus gemmeus AG

15b Gall c. 60 x 45 mm; white spots. Q. frainetto: Andricus quercustozae AG

15c Galls globular, about 8 mm across, with many thick conical spines, up to 1.5 mm long, similar to a horse-chestnut fruit, having a stalk about 1 mm long. A single larva. Adults in spring, Q. robur: Andricus hedwigia AG

16a Single galls egg-shaped to globular, white to red, later brown, 4–5 mm across, often several united to about cherry-size agglomerations. Surface with thread-like radiating appendages, tapering apically and about 5–10 mm long which are distantly white pubescent over their whole length. Wall thin and fragile. One larva per chamber. Q. petraea, pubescens, robur: Andricus serotinus AG

16b Galls rotund, 3–4 mm across; solitary or sometimes in unified clusters of 2–4; with densely covered bristles, 3–4 mm long, from a broad base gradually narrowed, glossy, white, bluish-red on tip, with 3–4 longitudinal grooves. Gall wall thin, woody. Containing a single larva. Q. infectoria, petraea, pubescens, robur: Andricus hystrix AG

17a Bud scales are not transformed or disappear partially or completely => 19

17b Bud scales are completely or partially involved in the gall development and are recognisable as modifications or remains => 18

17c Bud galls terminally on a thin twig in groups of 2–4. Q. robur:
Andricus quercuspyramidalis
?G

18a All scales on the strongly broadened bud base are considerably enlarged, resembling a larch- or a hop-cone, comprising a ± egg-shaped envelope, up to 20 (30) x 10–12 (20) mm. Outer scales brownish, dorsally usually glabrous, short and wide, triangular-rotund to egg-shaped, connected by intermediate forms to the inner, at first elongate-lanceolate, then short filamentous, white and pubescent leaf rudiments. In the middle an eventually brown, hard, egg-shaped, acuminate, one-chambered inner gall, up to 6 (9) mm long. “Artichoke or hop gall, oak rose”. Containing a single larva. Q. petraea, pubescens, pyrenaica, robur, frainetto, lusitanica, etc.: Andricus foecundatrix AG

18b Only the inner scale leaves strongly enlarged and coalesced. Gall rotund- to oblong-oval, slightly larger than pea-size, up to 10 mm long, greenish-white to reddish, succulent, with fleshy wall and (1) 2–3 (5) large larval chambers. Apical scales transformed into brown lobes, basal scales normal. One larva per chamber. “April gall”. All deciduous oaks: Neuroterus politus SG

19a Gall body in profile bell- to jar shaped, conical or variously structured, but not rotund or egg-shaped. Sometimes compartmentalised with several long protruding appendages => 41

19b Profile of galls, very different in size, ± uniform, globular, rotund- or oblong-oval, egg- to lemon-, cylindrically or also spindle-shaped, sometimes provided with tubercles, bumps or flat ridges => 20

20a Galls not differing substantially in longitudinal- or cross section, or acorn-shaped to cylindrical => 24

20b Galls distinctly spindle-shaped => 21

21a Short-stalked or sessile; stalk often to a large extent covered by bud scales => 23

22b Galls long petiolate, the stalk protruding far beyond the unopened bud. Petiole longer than the longitudinally ridged one-chambered gall => 22

22a Gall body about rice-grain size, 3–5 mm long, 2–4 mm thick, broadest in the middle, gradually tapering at both ends, ending in an elongated tip; initially yellow-green, eventually brown; on Q. petraea, robur glabrous, on Q. pubescens initially with distant, obliquely deflected hairs, which ± fall off later; usually with conspicuously red, protruding longitudinal ridges. Wall thin, almost woody. Gall from 5 onwards, dropping 7‒8. “Large spindle gall”. In the middle is a sizeable chamber containing a single larva: Andricus callidoma AG

22b Gall similar, but with short conical, papilla-like bare tip; with or without longitudinal ridges, green, later red to brown. Gall and stalk bear scattered shorter or longer deflected bristle hairs. Gall wall thin; large chamber in the inflated upper half of the gall, with a single larva. Q. petraea, pubescens, robur: Andricus amenti AG

23a Gall rice-grain size, stalk slender, shorter than gall or absent; gall developing from end- or lateral buds of lammas shoots, slightly thickened in the middle, green to brown with longitudinal ridges and an obtuse conical shiny tip, which reaches about a third of the length of the thin-walled, one-chambered gall body; develops in 9, dropping off in 10. “Little spindle gall”. Containing a single larva. Q. petraea, pubescens, robur, pyrenaica, lusitanica: Andricus malpighii AG

23b Gall body spindle-shaped to conical, about 10–12 (16) mm long and 3 mm wide, thin-walled, hard, with large chamber. Initially green, later brown-felt-like pubescent, eventually glabrous and glossy brown, ridges absent. Under part with short, thick, stalk (sometimes absent) inserted only between the small bud scales; tip of various length, usually bill-like or bent. “Brown felt gall”. Containing a single larva. Q. petraea, pubescens, robur. frainetto, lusitanica, etc.: Andricus solitarius AG

24a Galls globular, ± egg-shaped or rotund- to oblong-oval => 25

24bGalls ± slender acorn-shaped to cylindrical; 5–6 (8) mm long, 3–4 mm broad, sometimes narrowing gradually from the base to the tip; small blunt tip, in the middle with papilla-like little warts, glossy, glabrous. Wall rigid and thin, initially fragile succulent, soon drying out; outer layer green or reddish, with longitudinal ridges and whitish streaks or spots, later brown. At base enveloped by scales. Chamber large, containing a single larva. “White-spotted oak gall”. Q. petraea, pubescens, robur: Andricus paradoxus AG

25a Galls ± globular, usually less than 2 cm => 27

25b Galls not globular; when mature much larger than 2 cm => 26

26a Developed galls usually (1) 2–4 cm large; rotund, tuberculate or ± flattened and bulging bulb-shaped; apple- or potato-like. “Potato gall, oak apple”. Up to maturity succulent spongy, rather soft, whitish- to yellowish brown, sometimes reddish suffused, later darker brown and papery. Occasionally with mark of bud scales. Predominantly close to the attachment many tough-walled, oblong, ± radiating chambers. Each chamber with a white larva. All deciduous oaks: Biorhiza pallida SG

= Inquiline: Synergus gallaepomiformis.

26b Galls rotund to concave cup-shaped; (10) 17–35 (40) mm long; with somewhat distended tip; upper half with a distinct, equatorial rim of ± smaller to larger tubercles. Wall thick, spongy; outside brownish, sometimes coated silver-grey. Inside is an oblong eventually loose inner gall containing a single larva. Q. petraea, pubescens, robur, frainetto, pyrenaica: Andricus quercustozae AG

= Galls of Andricus insanus strongly resemble those of A. quercustozae but they are permanently viscous (those of quercustozae only when young) and the spines are not arranged in a neat circle, but rather scattered in several circles.

27a Galls only cherry stone-size => 34

27b Galls about 8–10 mm long or larger => 28

28a Surface always with wart- to tubercle-like, ± regularly arranged protrusions. Galls with flat conical basal part => 31

28b Surface glabrous, at most irregularly reticulate or with inconspicuous, irregularly scattered warts => 29

29a Galls about 8–10 mm long, globular or unequal rotund-oval, wall compact spongy or woody => 30

29b Galls almost spherical, 10–25 (30) mm long, glabrous or with very slight warts, occasionally finely striated; initially green and short pubescent, later yellow to dark brown, completely glabrous. Outer layer thin-walled, ± spongy and soft. Centrally an oblong chamber with fragile protective layer. “Marble gall”. Containing a single larva. All deciduous oaks. Andricus kollari AG

= Inquiline cynipid wasps:

1Synergus gallaicus

2 Synergus hayneanus

3 Synergus ibericus

4 Synergus pallidipennis

5 Synergus pallipes

6 Synergus radiatus

7 Synergus reinhardi

8 Synergus thaumacerus

9 Synergus tibialis

10 Synergus umbraculus

= Inquiline gall midge: Arnoldiola gemmae.

30a Galls usually globular, about 8–10 mm long; solitary or 2–5 together. Surface initially grey-green, later very hard, grey to red-brown, coarse, as result of covering of the upper layer with grey-whitish, irregular reticulate coating. Single chamber off-centre, exit hole always close to the point of attachment. “Cola-nut gall”. Containing a single larva. All deciduous oaks: Andricus lignicolus AG

30b Galls very similar to previous ones, but gall chamber situated closer to the gall wall. Solitary galls ± rotund, 8–10 mm long; usually in groups of 3–5 or more; gregarious galls smaller, flattened at contact area, ± pear-shaped. Surface glabrous, rarely rugose, green, later dirty yellowish-brown. Wall rough-porous, not woody. Chamber laterally, usually under a wart-like protruding pin-prick scar. Containing a single larva. Q. petraea, pubescens, robur, frainetto, etc.: Andricus conglomeratus AG

31a Galls irregularly coarse rugose or with isolated sometimes ridge-like connected tubercles => 32

31b Surface of 7–10 mm long galls subdivided into regular fields, similar to a closed acorn cup. Each small shield bearing a tubercle. Green in the beginning, then brown, short scale-like pubescent; with thick-walled, enclosed, one-chambered inner gall. Containing a single larva. Q. petraea, pubescens, robur, etc.: Andricus caliciformis AG

32a Galls with solitary tubercles or tuberculate ridges => 33

32b Galls spherical, 7–15 mm long, slightly narrowed at base, surface brownish-yellow. with coarse, irregular, tuberculate wrinkles. Protective layer of the gall chamber hard, wall softer. Containing a single larva. Q. petraea, pubescens, robur, frainetto, etc.: Andricus infectorius AG

33a Galls like the preceding ones, not rugose; red- to grey-brown, glabrous, hard and woody, 15–20 mm long. Larval chamber coalesced with the gall tissue; with irregularly placed, scattered coarse tubercles, especially apically. A single larva. All deciduous oaks.: Andricus gallaetinctoriae AG

33b Gall more or less spherical, but with a slight elongation to the point of attachment, reaching 10‒15 mm in diameter when mature, unilocular. The gall surface is sparsely covered with pointed protuberances, each 2‒3 mm long in the mature gall, and sometimes joined by raised ridges. Galls greenish-yellow when young, and a uniform pale sandy brown when mature. The wall of the mature gall is extremely hard and woody and it does not dehisce from the host. Q. infectorius, pubescens: Andricus sternlichti AG

33c Galls globular, usually 20–25 (45) mm, rarely only 13–20 mm long, dull brown, tubercles irregularly reticulate connected by ± protruding longitudinal ridges. Tissue inside brown, spongy, with large, irregular cavity, which containing a small, thin-walled inner gall, narrowly attached. Containing a single larva. Q. robur, pubescens: Andricus hungaricus AG

34a Gall oval- or egg- to lemon-shaped, thin- and ± tough-walled => 36

34b Galls ± globular, fleshy => 35

35a Galls globular to short rotund-oval, 4–7 mm long, with short tip, ± whitish to pale red. Surface glabrous, with scattered scale-like appendages. Wall thick, succulent; gall with central chamber. Containing a single larva. Q. petraea, pubescens, robur, frainetto, etc.: Trigonaspis megaptera SG

35b Galls similar to the previous ones; not different from the AG. Adults somewhat later than those of the previous species, still emerging in 7 of the first year, or also not before the second year. Q. petraea, pubescens, robur: Trigonaspis synaspis SG

36a Galls rounded at top; without wart-shaped appendage; ± ellipsoid to egg-shaped => 39

36b Galls at top with a distinct papilla; often ± lemon-like => 37

37a Gall narrowed at base, ± markedly attached by short stalk => 38

37b Galls mounted on a broad base, short, rotund-oval, usually somewhat broader than long, 3–4.5 mm long, single-chambered, about half enveloped by bud scales, on top with a yellow to rust red wart. Outer wall green, slightly succulent, later drying out, then with netlike surface. Inner wall woody, longitudinally furrowed, later blackish. often on small twigs sprouting from trunk. Containing a single larva. All deciduous oaks: Andricus inflator AG

37c Gall shape and size similar, but surface longitudinally ridged at maturity. Q. lusitanica: Andricus pseudoinflator AG

38a Galls mounted on wart-like base, at base enveloped by bud scales, looking like a globular lemon, up to 5 mm across, brown-yellow, darker on top, finely rugose, with deflected small hairs, single-chambered, wall thinner, with a free, completely spherical inner gall in the cavity. A single larva. Q. petraea, robur: Andricus clementinae AG

38b Galls lemon- to acutely egg-shaped, often 3–4 mm long and 2 mm wide, hard, glabrous, reddish, later brown. Below the dark tip is a narrow, whitish, belt-shaped ring. Predominantly solitary, sometimes pairs in a single bud. With only the upper third or fourth part protruding from the bud scales. Initially connected by a short stalk which reduces later on. “Collar gall”. Containing a single larva. Q. petraea, pubescens, robur, pyrenaica, etc.: Andricus curvator AG

38c Gall green, glabrous, thin-walled, ovoid, 2 mm long, 1.5 mm in diameter; protruding from the bud by a third only or completely hidden. Gall dropping off. Q. petraea, pubescens, robur: Andricus gemmicola SG

39a Galls egg-shaped, green or ± reddened, glabrous => 40

39b Galls in spring, ± egg-shaped, 3–5 mm long, at base with inconspicuous bud scales, green or ± reddish, thin-walled, soft. Surface densely covered with usually brownish-red, distal small hairs. Containing a single larva. Q. pubescens: Cynips quercus SG

40a Galls egg-shaped to rounded cylindrically, in autumn; 3.5–5 x 2.5–3.5 mm, sometimes with short little warts at the tip; basal part halfway to two-third enclosed in bud scales, whitish coloured. Outer layer thin, glabrous, somewhat succulent, the exposed part olive-green, later rose-red to violet, eventually drying out, brown and longitudinally keeled like the inner layer. Wall thin. Chamber elliptical. Containing a single larva. “Whitefoot gall”. Q. petraea, pubescens, robur: Andricus quercusramuli AG

40b Gall body at base not enclosed by bud scales, usually ± obliquely protruding on short stalk; elliptical, width about 2–3 mm and length 2–2.5 mm, sometimes smaller. Wall glabrous, thin, dark-coloured with irregular brighter stripes, appearing slightly roughened. In the conspicuously large cavity is a single larva. Q. pubescens, rare on Q. petraea: Andricus trotteri AG

41a Galls appearing deeply subdivided into an upper and basal part, respectively acute transversely constricted, or with several conspicuous protrusions or appendages => 47

41b Gall body not deeply subdivided, of different shape, ± conical, cup-, or urn-shaped, sometimes with bulges => 42

42a Galls glabrous, sometimes viscose => 44

42b Galls velvet-like pubescent => 43

43a Galls on younger shoots in late summer, length 3–6 mm, width 2–4 mm; green to dark red, occasionally on the same shoot; quite variously shaped, bell-shaped to obtusely conical, on the tip with small hairless brown warts, at base with an inward curved bulge; in other cases at base cup-like widening, on top ± rounded, more rarely flattened, the wart on top ± countersunk. In all cases covered in a deflected, white or ± violet, silk- to velvet-like pubescence. Wall rather soft; one larval chamber with distinct cavity above or very loose parenchyma. Q. petraea, pubescens, pyrenaica, rare on robur, etc.: Andricus glandulae AG

43b Galls bell-shaped, similar to the previous ones, but with long, cylindrical, thick stalk. Upper part elongate, ± cylindrical; basal part with thick, rounded tubercles at base. Containing a single larva. Q. petraea, pubescens, robur: unidentified subsp. of Andricus glandulae AG

44a Overall shape of galls rotund, cup-, urn-like, or consisting of a broad basal part with a narrow cylinder on top => 45

44b Galls slender conical, with abruptly narrowing, usually hollow apical part, about 5–6 mm long and 4 mm wide, brown, glabrous or with rather long deciduous hairs, longitudinally striate up to tip. Wall hardly thickened, slightly woody. No inner gall. Chamber containing a single larva in basal part. Q. petraea, robur: Andricus paradoxus AG

44c Gall oblong-ovoid, almost cylindrical, 6–8 x 3 mm, woody, glabrous, the upper half longitudinally striate, a little but distinct navel on apex; larval chamber large, thin-walled. Q. petraea, pyrenaica: Andricus lichtensteini SG

45a Galls up to only10 mm => 46

45b Gall 17–40 mm long, rotund or ± cup-shaped. In the upper part with a belt-shaped circle of smaller and larger tubercles, about 5–6 mm long. The lid-like apical part weakly arched with somewhat extended tip. Glossy brown, ± silver-grey coated. Wall thick, brown, spongy. At the level of the ring centrally is an oblong, transversely situated inner gall in a flat, wide cavity. Containing a single larva. All deciduous oaks. Andricus quercustozae AG

= Galls of Andricus insanus strongly resemble those of A. quercustozae but they are permanently viscous (those of quercustozae only when young) and the spines are not arranged in a neat circle, but rather scattered in several circles

45c Gall rotund, one-chambered, 20–30 mm across, a small spongy, surface covered with flat pyramidal warts. The tip of these warts is bluish when young, The base is red and the middle part yellowish. Q. robur, lusitanica, pyrenaica: Andricus curtisii SG

46a Gall urn-shaped, up to 10 mm long, broadly attached to the twig, ± enveloping and overtopping it laterally Basal half swollen, without interruption, passing over into a narrower, apically slightly narrowing upper half. Terminal part groove-like depressed, in the middle with wart-like tubercles. Fresh yellow or red and ± sticky, or dry yellow and hardly sticky. In a large central cavity is an initially attached, later free, thin-walled egg-shaped inner gall. Containing a single larva. Q. petraea, pubescens, pyrenaica, robur, etc.: Andricus glutinosus AG

46b Gall oblong-conical 12–28 mm across, embracing the twig and some petioles; surface brownish deciduous pubescent, eventually the upper part of the cone is slightly broadened, the centre with a navel-like depression. One large basal chamber containing a single larva. All deciduous oaks: Andricus tomentosus AG

46c Gall bowl-shaped, pale yellow, glossy, stalked. Stalk about 6–8 mm long and 1.5–3 mm thick. The bowl is 15–22 mm in diameter, the margin deflected, sometimes fimbriate; at the place of attachment is a cavity with ovoid inner gall. Q. petraea, pubescens: Andricus stefanii AG

46d Gall up to 10 mm long, bipartite. Basal part flat expanded, ± lobed, enveloping the shoot axis, up to 3 mm long and 10 mm wide. The centrally mounted cylindrical or ± obtuse conical gall, flattened at tip and ± depressed, up to 7 mm long and 3–4 mm wide. Whole gall red- to chestnut brown, ± sticky, glossy. With an oval inner gall in the basal part. Containing a single larva. Q. dalechampii, petraea, pubescens, robur: Andricus mitratus AG

47a Gall body undivided, with conspicuous, stalked or several variously shaped appendages => 51

47b The gall body appears ± subdivided => 48

48a Subdivision in longitudinal direction => 49

48b Length of gall body about 8 mm, abruptly transversely subdivided. Basal part rotund-oval, 4–5 mm wide, 2–3 mm long, brown red, ± occupied by rather long, fine, woolly, white hairs. The hollow onion-like upper part, up to 5 mm wide running on top into several simple or forked, short, thread-like appendages. Appendages short pubescent, longitudinally grooved, with pith inside. An oval larval chamber in the basal part containing a single larva. Q. petraea, pubescens, robur: Andricus galeatus AG

49a Under part of the early woody galls short cylindrical; appendages on the upper part only => 50

49b Galls with wide oval basal part, about 3–4 mm long, fleshy during longer time, at their free surface occupied by many papillae from gall base to tip rapidly increasing in length, obtuse-conical, terminally pubescent; in the basal part is a large wide-oval chamber containing a single larva. Q. robur, more rarely Q. petraea, pubescens, lusitanica: Andricus gemmeus AG

50a Basal part of the early woody galls cylindrical, 4–6 x 2.5–4 mm, usually standing on a strongly swollen branch stump. Upper part usually divided into 2–4 (5) conical or rotund, 2–4 mm long, acutely-angular erect, glabrous lobes, between them laterally the actual tip showing a flat, coarse little “rosette”. Surface red-brown to bark-coloured, glabrous, ± glossy, irregularly disrupted. Wall woody. Gall chamber in basal part with a single larva. “Lappet gall”. Q. petraea, pubescens, robur, etc.: Andricus corruptrix AG

50b Basal part of the gall short cylindrical; standing on the not thickened twig. Upper part with (2) 3–4 (6) usually obtusely-angular upward and outwardly directed projections, short conical, with papillate appendages, between the actual tips, a small wart provided with a dense, woolly hairline. Gall hard, 4–6 mm long; surface grey to red-brown, fissured, fine velvet-like pubescent and dull. With a large, transversely situated, oval chamber lacking a particular protective layer in the basal part. Containing a single larva. Q. petraea, pubescens, robur: Andricus amblycerus AG

50c Galls similar, rotund, but about 7–8 mm long; appendages much shorter and broader, glabrous at tip, provided with a wart. With distinct inner gall. Containing a single larva. Q. petraea, robur: Andricus corruptrix AG

51a Galls multi-chambered, with appendages all over the surface => 54

51b Galls one-chambered, with thinner or thicker crown-like arranged appendages => 52

52a Appendages extending from a disk-like apical plate => 53

52b The basal gall body, with broad basal attachments, slender onion-shaped, 5–8 mm long and 4–6 mm wide, one-chambered, then passing into two tapering, conspicuous horn-shaped projections, up to 50 mm long, hollow, to the tip sometimes repeatedly subdivided, which may be fused into a single strap, or reduced to two points. Containing a single larva. “Ramshorn gall”. Q. petraea, pubescens, robur: Andricus aries AG

= Inquiline gall wasp: Ceroptres clavicornis

53a Gall body rotund, cup-shaped or inverted bell-shaped, 10 to 12 mm long, at top 12–15 mm wide; flattened here and in the middle with groove-like depression, passing into several coarse horn-like projections, the terminal half narrowed, usually deflected upward and outward, 5–8 mm long, occasionally with a similar double crown. In fresh condition yellow, here and there ± reddened, basal part sticky; when dry, brownish and not sticky. Inside a small central cavity is an inner gall, attached above and below. Containing a single larva. Q. petraea, pubescens, robur, frainetto: Andricus coronatus AG

53b Gall inverted conical to bell-shaped, 12–15 mm long and almost of same width above; not sticky. Upperside almost disc-like, in the middle somewhat elevated, with a central wart; the margin ± sharp-edged, with 3–5 outwardly directed lappets, ± upwardly and downwardly bent, flattened and gradually tapering, up to 10 mm long, sometimes extending starfish-like. In fresh condition greenish and ± reddened, later brownish-yellow. Inner gall large, spherical, cartilaginous with coarse longitudinal striations. Containing a single larva. Q. petraea, pubescens, robur, frainetto, fruticosa: Andricus polycerus AG

53c Galls similar, about 8 mm long; in the bell-shaped part finely striate, brick-coloured. Upper part more brightly coloured, with four elevated, flat-triangular protruding appendages, which form a wide, slightly cross-shaped disc, with a papilla in its middle. A single larva. Q. petraea, pubescens: Andricus stefanii AG

53d Gall generally bell-shaped, 12‒15 mm in length when mature. The upper, distal surface of the gall is a flat or slightly concave surface from the rim of which radiate 3‒6 (most frequently 4) stout spines, often curved at their tips. The upper surface usually has a small tubercle at its centre. The young gall is green, and sometimes matt in texture due to a coating of fine white powder. In other cases, the gall can be shining, or pubescent, or even (very rarely) glutinous. As it matures the gall turns a reddish brown. The single globular larval chamber is located in the upper part of the gall, 7‒8 mm across, with a thick, hard wall. Though the peripheral tissue in young galls can be quite soft, when mature the central parts are very woody, and bisection reveals a structure of radiating fibres around the larval cell. The gall remains on the tree for a long time after emergence of the adult insect. Q. petraea, pubescens, robur, hartwissiana, lusitanica: Andricus subterraneus AG

54a Appendages of various size and appearance, scattered => 55

54b Appendages of almost similar appearance, very many, covering the globular to oval, cherry- to hazelnut-sized gall bodies, spiny, 4–8 mm long, sticking out rigidly radiating, tipped with a small knob, often red and sticky. Old galls persist but lose spines. Inside the livid yellow, thick-walled woody gall are several larval chambers each containing a single larva. “Hedgehog gall”. Q. petraea, pubescens, robur, frainetto, lusitanica, etc.: Andricus lucidus AG

= Inquiline gall wasp: Synergus umbraculus.

54c Galls much smaller, up to 8 (10) mm across with spines only 2–4 mm long, with rounded tips and appearing longitudinally striate: Andricus lucidus AG

55a Basal part of the brown gall about 10–20 mm wide, irregularly rotund-oval, apically often widening, only rarely narrowing; at the end flattened and predominantly bearing many rigid, 5–10 mm long, irregular, usually strongly curved, compressed, longitudinally grooved horn-like tapered appendages, sometimes ± coalesced at their bases. Inside many, ± oval chambers each containing a single larva. All deciduous oaks: Andricus coriarius AG

55b Galls similar. However, appendages straight or only weakly curved, not horn-like and tapered, compressed, longitudinally striate, yellow-green, sticky, 5–15 mm long, 2–4 mm wide. Q. petraea, pubescens, robur, frainetto, pyrenaica, etc.: Andricus pictus AG

= Andricus grossulariae AG develops exclusively on catkins in similar, but smaller galls.

= Andricus bulgaricus AG causes a bud gall on Q. pubescens, usually solitary. The gall is unilocular, elongated, narrower at the base broadening towards the apex. Galls are 11‒23 mm long and 7‒9 mm in diameter in their broadest apical part, gradually narrowing towards the base.

Deciduous oaks, on leaves

1a Galls are open and often of undefined shape. Openings of many galls often only recognisable with difficulty => 34

1b The inducer develops during all its immature stages in galls completely closed on all sides => 2

2a Galls of defined, distinct shape on the leaf blade, on the leaf margin, or distinctly breaking out of the hardly modified venation => 7

2b Swellings of petiole or of leaf venation, but not clearly protruding => 3

3a Caused by gall wasp larvae. Larval head hardly contrasting, thoracic legs absent. Galls predominantly on the venation; on petioles only simultaneously appearing with those on leaf surface => 4

3b Petiole ± shortened and bent, distinctly swollen over all its length. Gall often far more pronounced on short stalked oaks than on long stalked ones. The mature larva cuts an oblong-oval shelter terminally from the gall. Larva with distinctly contrasting head and with thoracic legs. On deciduous oaks: Heliozela sericiella

4a Galls ± spindle-shaped, considerably longer than wide; recognisable on the leaf veins usually only on the underside; with membranous-leathery wall => 5

4b Galls on main and subordinate veins; ± globular to rotund-oval, 5–8 mm across; in adjacent leaf blade areas protruding on both leaf sides; sometimes with several ± coalesced and distorting the leaf. Upperside glabrous, underside sometimes weakly pubescent; on Q. pubescens both sides ± haired. Wall succulent. Centrally a thin-walled cavity with an eventually detached inner gall. about 2 mm long. Containing a single larva. Q. petraea, pubescens, robur, frainetto, lusitanica and many other cultivated deciduous oaks: Andricus curvator SG or, southern localities: Andricus curvator var. lusitanica SG

5a Swellings on petiole and midribs, predominantly on underside, mostly ± expanded spindle-shaped, up to 8 mm long, yellowish, later brownish, sometimes multi-chambered; occasionally on smaller veins but then smaller, ± short spindle-shaped and one-chambered, several per leaf and sometimes coalescing => 6

5b Galls also on petioles and main veins, always small and one-chambered, about 1.5 mm wide and 2.5 mm long, with small inner gall. Containing a single larva. Q. petraea, robur: Andricus testaceipes SG

5c Swelling of a main vein or the petiole, 2.5 mm long, fusiform; the gall has an inner gall. Q. petraea, robur: Andricus nodifex SG

5d Midrib of very young leaves locally swollen, with oval egg capsules (procecidia, oviposition scars, not true galls). Larva living externally on the leaf blade, initially pale green with black head capsule, provided with 5 rows of bifurcating setae; standing on black warts later on orange-yellow, eventually losing their setae. Q. robur, less frequent on Q. petraea, also on Q. rubra, rubra var. maxima, etc.: Periclista lineolata

6a Galls slightly arched, usually solitary, also on lateral veins; up to 5 mm, whitish or brownish, occasionally, if several, forming a longitudinal bulge. Each chamber with a single larva. On deciduous oaks: Andricus quercusradicis SG

6b Galls similar but greener; predominantly clustered. Solitary galls often stronger arched, only exceptionally on axial parts. Each chamber with a single larva. On many deciduous oaks, also on evergreen species: Andricus testaceipes SG

6c Gall within leaf petioles, has a straight axis in the petiole, and a smooth surface. A longitudinal swelling along the petiole axis, many times wider than the original width of the vein. Individually monolocular galls may fuse along the vein. When young, the galls are slightly paler in colour than the petiole. The gall surface is smooth when young, but with age may become longitudinally ridged. The tissue of the gall is soft and moist at first, later drying and becoming harder. The galls fall with the leaves. On many deciduous oaks: Andricus sieboldi SG

Note Many authors attributed the AG of sieboldi to testaceipes. Unravelling the literature is complicated – see Meika (2006a)

= Callirhytis tumifica SG, native to N-America, has been recorded on leaf ribs and acorns of Q. rubra. The AG might very probably be attributed to C. fructuosa AG, galling acorn cups of Q. rubra and also native to N-Am on Q. rubra

7a Galls on leaf blade or venation => 12

7b Galls on sometimes heavily notched or bent-in leaf margin => 8

8a Galls usually with narrow base attached on margin at site where leaf vein ends => 9

8b Galls with longitudinal side attached on leaf margin, often in ± deep indentation or tear of the leaf blade, at end of main- or side vein. Oblong-ovate, 1.5–2 x 1–1.5 mm, pale green to yellowish-white; the early phase with distant hairs; later on glabrous, thin-walled; on the free side often with small warts. Containing a single larva. On many deciduous oaks: Neuroterus albipes SG

= The procecidia (oviposition scars, not true galls) on veins of developing leaves of the sawfly Periclista lineolata are sometimes similar to the preceding galls.

9a Galls with distinct longitudinal rims => 11

9b Galls without such rims, with granulate or tuberculate surface => 10

10a Galls appearing flat-lustrous, covered with tiny liquid-filled pustules, blunt cone-shaped to cylindrical, 3–5 mm long, 2–2.5 mm wide, the basal third somewhat widened; green-yellowish or reddish, thin-walled. Containing a single larva. On many deciduous oaks: Cynips divisa SG

10b Galls without such pustules; finely tuberculate, ± conical or slender egg-shaped, up to 5 mm long and 2.5 mm wide, thin-walled; very similar to the previous species. Containing a single larva. “Red wart gall”. On many, also exotic, deciduous oaks: Cynips disticha SG

10c Similar galls, difficult to distinguish from previous two species, rearing of adults necessary: Cynips agama SG

11a Galls egg- to pear-shaped, 3–4 x 2–3 mm, sometimes slightly curved, glabrous, thin-walled, initially green, later on brown, slightly grooved and with several irregular red or pale green longitudinal ridges. Containing a single larva. “Rimmed leaf margin gall”. Q. petraea, robur: Andricus quadrilineatus AG

11b Gall spindle-shaped, about barley-corn size, sessile or ± long petiolate, in that case 6–14 mm long; green, with red or pale green longitudinal ridges, with scattered short hairs; often in deep indentations, almost situated on the midrib. Terminally a wart possessing a crown of hairs. Thin-walled, containing a single larva. Q. petraea, robur: Andricus seminationis AG

12a Galls on the leaf blade or on the subordinate venation => 14

12b Galls almost exclusively on or lateral to the main venation => 13

13a Galls flattened rotund-oval; laterally protruding on the main venation, the longitudinal axis parallel to the venation. The outer gall soon stops its growth, dries out, tears open and embraces by two valves the basal part of the further growing inner gall. The latter is 2–4 x 2–3 mm, glabrous, glossy, tough-walled, initially green or yellow, later on with many red to violet dots or spots. “Oyster gall”. Containing a single larva. On many deciduous oaks: Neuroterus anthracinus AG

13b Gall irregularly kidney- or bean-shaped, rarely ± ovate, 2–4 mm long, pale green or partially ± reddened, glabrous. Often arranged in rows, attached with a minute stalk on the mid- or main lateral veins. Longitudinal axis along the vein, flatly appressed to the leaf blade; thin-walled; inner gall absent. “Kidney gall”. Containing a single larva. On many deciduous oaks: Trigonaspis megaptera AG

13c Little spindle-shaped gall, 4 mm long, 1.5 mm thick, almost woody, white, attached by a thin stalk to the underside of the lateral veins and parallel to these; the distal side of the gall covered with long hairs, underside almost glabrous; thin-walled elliptic larval chamber. Adults emerge in spring of the following year. Q. faginea, pyrenaica: Trigonaspis brunneicornis AG

13d One, often more, elongate-starlike galls on the underside of a leaf, lengthwise attached to a thick vein; the end points are free. The longest axis is about 3 mm long. The surface has irregular ridges and is white-hairy. Q. canariensis, lusitanica: Trigonaspis baetica AG

13e Oval, 3.5 mm long swelling of the underside of the midrib, covered by long, whitish hairs. Q. robur: Andricus gallaecus ?G

13f Strong swelling on the underside of a leaf, attached to a vein. The gall measures 15 mm and is multilocular. Q. ithaburensis subsp. macrolepis: Andricus melikai ?G

14a Galls usually point-wise attached on a side vein, protruding on a single leaf side => 21

14b Gall in the leaf blade or attached with a broad base, protruding on both sides => 15

15a Galls spherical or pustular- sometimes lenticular flattened; on both leaf sides similarly protruding => 17

15b Galls on underside almost globular, only flat disc-shape emerging on the opposite side => 16

16a Galls vitreous berry-like, almost spherical; with thick, very succulent translucent wall; 4–7 mm across, glabrous or in case of Q. pubescens with scattered short hairs; pale green, sometimes ± reddish marbled. On the upperside visible as a slightly arched, broad disc. “Currant gall”. Containing a single larva. On many deciduous and evergreen oaks: Neuroterus quercusbaccarum SG

16b Galls a flattened sphere, often several coalescing, initially with erect, long, white, also violet hairs which drop off later on; usually smaller than the previous ones, only 4–6 mm across, appearing a little later; wall not vitreously translucent as in the previous species; thick, succulent, milk-white or grey-green, sometimes with a reddish-violet gloss. “Bristly globular gall”. Containing a single larva. On many deciduous oaks, even on evergreen species: Neuroterus tricolor SG

17a Lenticular- or pustule-shaped parenchyma galls => 18

17b Galls close to a vein, protruding ± hemispherically on both sides of the leaf blade; up to 7 x 12 mm long. Often coalesced in clusters and ± disfiguring the leaf. Green, succulent, ± cartilaginous. Glabrous above, on the underside pubescent, in Q. pubescens on both sides long-haired. Mature galls with large cavity and about 2 mm long, whitish-yellow to pale brown, free inner gall. Containing a single larva. On many, also cultivated deciduous oaks: Andricus curvator SG

18a Galls contain larvae => 19

18b The hour glass-like arched, especially recognisable on the underside, pustule-shaped, solitary swellings each contain an egg. “Procecidia”, oviposition scars, not true galls. The emerging, slime-covered larva feeds on the leaf blade. Q. petraea, robur: Caliroa annulipes

19a Galls induced by gall wasp larvae with powerful biting mouth parts on the small, but clearly eyeless head => 20

19b Malformations caused by midge larvae lacking such mouthparts. Rotund, about 2–4 mm long, slightly arched, slightly discoloured, irregular, inconspicuous pustules. The single larva leaves the gall by a centrally situated exit hole on the leaf underside. On many deciduous oaks: Janetia panteli

19c Distinct blister on upper surface of leaf blade (central depression may appear in old gall); containing white gall midge larva which escapes via a hole in lower surface. Q. petrea, pubescens, robur: Polystepha malpighii

19d Similar galls. Q. robur: Polystepha quercus

20a Rotund, up to 3 mm x 1 mm, initially green, later on ± browned parenchyma gall. Inside is a minute, inner gall coalesced on all sides. Containing a single larva. Q. pubescens, robur, frainetto, lusitanica: Andricus gallaeurnaeformis SG

20b Galls similar, pale green, also later hardly discoloured. On the upperside rather distinctly arched, radially striated, with central, small tubercles, on the underside only flatly protruding. Inner gall absent. Containing a single larva. Q. petraea, pubescens, robur, cerris, etc.: Neuroterus numismalis SG

21a Galls either much wider than high, disc-shaped or lenticular, broadly attached to the leaf, or the galls beaker- or urn-shaped => 28

21b Galls ± spherical or rotund-oval => 22

22a Mature galls only up to 8 mm across, glabrou => 25

22b Mature galls about 8–10 mm across or larger, glabrous or bulging => 23

23a Gall wall glabrous, especially when young, ± finely tuberculate => 24

23b Mature gall 8–10 mm across, rotund-oval, flattened on the underside, yellow or mostly red; with lighter, variously spiralling or annular broad- and flat-bumped bands; thick and tough-walled; with a large transversely-elongate chamber. “Striped pea gall”. Containing a single larva. Q. petraea, pubescens, robur, dalechampii, frainetto: Cynips longiventris AG

24a Galls (10) 15–20 (25) mm across, yellowish or on the sun side ± reddened, glabrous. Surface smooth or with little warts. Wall very thick, till maturity ± succulent, spongy, later on brown, partially shrinking. Centrally a small, rotund chamber, with a thin but tough layer. “Cherry gall”. Containing a single larva. Q. petraea, pubescens, robur and other deciduous oaks: Cynips quercusfolii AG

= The snout beetle Archarius pyrrhoceras lives as an inquiline in agamic galls of Cynips quercusfolii.

24b Galls about 10 mm across, spherical, pale brown, dull, with some flat warts and sometimes ± white frosty; thick-walled; missing an inner protective layer. A rotund, about 4 mm wide central chamber containing a single larva. Q. pubescens, lusitanica, much rarer on Q. petraea, frainetto and some other, even evergreen oaks: Cynips quercus AG

24c Little spherical gall, smooth, not shining, yellowish sprinkled with brown-black round spots. Q. pubescens: Andricus giardias ?G

25a Wall only initially soft, soon dry and hard, galls in late summer and autumn => 26

25b Galls only present in spring and early summer. The thick wall is succulent until maturity with exception of a thin, hard inner layer. Galls spherical, 5–7 mm across, initially ± pale green, reddened when mature, sometimes yellow dotted. With central larval chamber, its size equalling almost the wall width. Containing a single larva. Q. petraea, pubescens, robur, lusitanica and other deciduous oaks: Trigonaspis synaspis AG

26a Galls with only one cavity => 27

26b Galls rotund-ovate, above the larval chamber a second empty one. Usually with several on the side veins; 4–6 mm across, smooth or bumpy surface; narrowed at base, flattened at top and often with ± depression and centrally a navel-like protuberance. Wall hard. Containing a single larva. Predominantly on Q. petraea, much rarer on Q. pubescens, robur, lusitanica, also on other deciduous, even evergreen, oaks: Cynips disticha AG

27a Galls rotund-ovate, 4–6 x 5–8 mm wide, at base and top slightly flattened; initially green, soon reddish, later on brown, glossy; almost woody. Often many on mid- and side veins. Chamber elongate transverse, relatively thick-walled. Containing a single larva. “Pea gall”. On many deciduous oaks: Cynips divisa AG

27b Galls egg-shaped to oblong-elliptical, 3–4 mm high, initially yellowish-white, later on brownish-yellow, not reddened, almost dull, glabrous or slightly tuberculate. Wall thin, hard, brittle. A relatively large chamber containing a single larva. Predominantly on Q. petraea, more rarely on Q. robur, pubescens: Cynips agama AG

28a Galls beak- or urn-shaped; species from SE Europe => 33

28b Galls disc-shaped or lenticular, dropping off in autumn; on indigenous oaks, sometimes in large numbers on the leaf underside => 29

29a Galls variously, ± densely pubescent => 31

29b At least the older galls completely glabrous => 30

30a Gall flat, disc- to cup-shaped, 3–4 (5) mm across. Underside flat, upperside with raised centre, ± distinctly radially striate. Margin often irregularly rim-like, bent upwards. Initially upper surface with scattered stellate hairs, soon completely glabrous. Yellow, ± reddish to dark purple-red. Often in clusters mainly on the leaf underside. “Smooth spangle gall”. Containing a single larva. On many deciduous oaks: Neuroterus albipes AG

= The inquilinous gall midge Xenodiplosis laeviusculi, living between gall underside and leaf surface may cause additional malformations.

30b Galls similar, only the margin with 3–4 or more lobes tricorn- or star-like broadly bent upwards, sometimes consisting of only the central bump. Otherwise like the previous gall; on same hosts. Neuroterus albipes f. sp. reflexus AG

30c Flat gall, little pubescent, 5 mm across. Q. faginea, pyrenaica, robur: Neuroterus albipes f. sp. lusitanicus AG

31a Galls ± flat, rotund, lenticular; densely covered with stellate hairs. Upperside with raised centre; cross section triangular or bowl-like. Larval chamber short lenticular, protective layer absent => 32

31b Galls relatively thick disc-like; flattened on the underside. On the upperside with deep central pit; surface hidden by flat golden silky hairs. About 2–3 mm wide and 1.5–2.5 mm high. Inside is an expanded acuminated, broad oval chamber provided with a protective layer. “Silk-button gall”. Containing a single larva. On many deciduous oaks. Neuroterus numismalis AG

= Inquiline gall wasp: Synergus albipes. – Occasionally the galls develop together with Neuroterus quercusbaccarum, the galls of which may become disfigured

32a Gall lenticular, brownish-yellow, initially reddened; underside flat and glabrous, upperside smoothly rising towards the obtusely angled mound; in cross section flat triangular; up to 4–6 mm wide, about 2 mm high; densely covered with large red-brown stellate hairs; the margin often white spotted. Underside appressed to the leaf. Dropping off. “Frequent spangle gall”. Containing a single larva. On many deciduous, also cultivated, oaks: Neuroterus quercusbaccarum AG

32b Similar gall, 6 mm across, sparsely covered with reddish hairs. Adults 2 of the following year. Q. robur, pyrenaica: Neuroterus quercusbaccarum AG

= Inquiline gall midge: Parallelodiplosis galliperda

32b Galls lenticular to bowl-shaped, 2–3 x 1–1.3 mm, brown-yellow to reddish; margin blunt, ± bent upwards, without white dots. Middle part clearly arched. On the upperside with scattered, large rust-brown stellate hairs, on the underside more sparsely pubescent. “Cupped spangle gall”. Containing a single larva. On many deciduous oaks: Neuroterus tricolor AG

33a Galls cornicular, up to 10 mm high, rarely larger, middle or basal part ± constricted, at base broadened, however the leaf underside attached with only a short, thin stalk. Green, later on brownish-yellow and ± reddened, glossy, hard. Chamber in the basal part, containing a single larva. Q. lusitanica, petraea, pubescens: Cynips cornifex AG

= Cross-matings between C. cornifex and C. quercus may result in galls of intermediate shape

33b Galls urn- to barrel-shaped, about 3 mm across; gradually narrowed upwards from basal third; terminal part flat, with central flat tubercle surrounded by a slightly elevated annulus. Wall green, red or red-brown, longitudinally grooved. With large, oblong-oval, inner gall, attached on all sides; containing a single larva. On many deciduous oaks: Andricus gallaeurnaeformis AG

33c Gall shuttle-shaped, 4–5 mm long, red, glabrous, woody, attached on the midrib (rarely on a secondary vein) with a cylindrical, slightly striated, stalk; larval chamber ovoid. Q. faginea, lusitanica: Trigonaspis mendesi AG

34a Galls on leaf blades delimited locally; sometimes with many together => 37

34b Large part, or whole leaf blade disfigured (somewhat ± crumpled malformations on developing leaves caused by gall mites or aphids) => 35

35a Leaf margin ± rolled. Leaf blade ± mottled discoloured to browned, often with other malformations, which represent merely stunted malformations rather than true galls; caused by mites => 36

35b Leaves of spring shoots deflected, rolled or curled, hardly discoloured; contain aphids. Q. petraea, pubescens, robur: Thelaxes dryophila

35c Leaf underside with scattered blister-like swellings, containing uredinia and telia of rust. Quercus spp.: Cronartium quercuum

36a Shape of leaf blade ± changed, with irregular, yellowed spots; venation irregular. Q. petraea, pubescens, robur etc.: Rhyncaphytoptus massalongoianus

36b Leaf margin undulate; ± upwardly reflexed. Q. pubescens, robur and other oaks: Acaricalus cristatus

37a Leaf blade with groove-like or bladder-shaped depressions, folds along the veins or with erinea => 41

37b Leaf blade with localised roll, or leaf margin folded => 38

38a Leaf margin folded up- or downwards => 39

38b Margin usually in the indentation of the lobes mainly upwardly and narrowly rolled, tube-shaped. Roll thickened, not- or only slightly discoloured; inside 1–3 (5) initially white, later on orange, especially at the ends, midge larvae. On many deciduous oaks: Macrodiplosis roboris

39a Margin of young spring leaves mostly bent downward along short length and width; bowl- or mussel-shaped. The inducer is located on the bend on the somewhat widened and ± discoloured vein. The insects leave the galls from end of 5 onwards and live freely on the leaf blades which are soon strewn with dried-out spots close to the suction sites. Dwarf aphids host-specific, identification difficult and only on microscopic characters => 40

39b End of lobe broadly downward deflected, closely appressed to the leaf surface; slightly thickened, slightly discoloured and sometimes yellow to red spotted. Containing one (to several) yellowish-white to yellowish larvae. On many deciduous oaks: Macrodiplosis pustularis

= Outwardly similar are the leaf margin folds caused by spinning activities of mining caterpillars which belong to the microlepidopterons Caloptilia alchimiella and C. robustella

40a Aphid distinguished by the minor development of the dorsal tubercles, the marginal ones are slightly elevated. Q. robur: Phylloxera glabra

40b Aphid distinguished by a conspicuous latero-dorsal row of dorsal tubercles; spinal and pleural rows may be distinctly weaker. On many deciduous oaks: Phylloxera coccinea

40c Dorsal tubercles of the aphid arranged uniformly. On many deciduous oaks: Phylloxera foae

= Phylloxera confusa. Fundatrices feed from veins on undersides of oak leaves, causing the lobe of the leaf distal to the feeding point to fold inwards

= Phylloxera quercus, S-Europe, alternates between evergreen and deciduous oaks

41a Leaf blade with groove-like depressions, elongate leaf folds or pustule- to bladder-like archings => 43

41b Leaf blade often with extensive erinea => 42

42a Erinea on the underside; rust-brown. Hairs partly longer and strongly twisted, partly shorter, slightly bent or cylindrical and slightly club-shaped. Q. petraea, pubescens, robur and other deciduous oaks: Aceria quercina

42b Erinea on Q. frainetto: Aceria suberina

43a Depressions groove-like, rotund, about 3 (4) mm across => 45

43b Leaf blade with bladder-like swellings or folds along the side veins => 44

44a Leaf blade alongside vein of seedlings with a downwardly protruding fold. The respective vein swollen and slightly bent. Q. petraea, robur: Dasineura panteli

44b Leaf blade usually with several, inconspicuous swellings or bladder-like malformations of various dimensions, arched on the undersides and showing clearly on upper side. In the cavities, predominantly on the underside develop downy mycelia of the fungus: Taphrina caerulescens

45a Depressions about 3 mm wide, containing the inducer on the leaf underside; usually many per leaf blade => 46

45b Depressions only about 1 mm wide, usually several per leaf blade; contain flat froth-covered nymph. Q. macranthera, petraea, pubescens, robur, rubra:
Trioza remota

46a Galls already in early spring just after unfolding of leaves, usually many per leaf. The leaf tissue is ring-like and swollen around the sucking larva. The mature fundatrix soon moves into the bark furrows of branches and stems. Q. petraea, robur and other deciduous oaks: Acanthochermes quercus

46b Underside of leaf with round flat depressions, 3 mm across, containing a gall midge larva. Q. petraea, pubescens, robur: Arnoldiola libera

Deciduous oaks, on male inflorescences (catkins)

1a Malformations of only parts of the catkins => 2

1b Complete catkins disfigured, shortened, swollen. Several red larvae between the flower parts. Q. pubescens, robur: Contarinia amenti

2a Gall glabrous or with hairs which are shorter than the galls => 4

2b Actual gall 1–3 mm long, bearing very long, ± distant, woolly pubescence => 3

3a The galls develop from the male buds on stumps of stunted axial parts; often 10–20 in a single bud. Each of the about 2 mm long, oblong and hard galls bears on its free surface long, initially turgid white-, later dried, flattened, twisted and ± browned hairs, forming together a 20 mm long ball which largely conceals galls and buds, sometimes overtopped by ± short tufts, some bearing anthers. “Cotton-wool gall”. Each gall containing a single larva. Q. petraea, pubescens, robur, frainetto, pyrenaica, lusitanica, ? cerris: Andricus quercusramuli SG

3b The roughly egg-shaped galls, up to 2 mm with tufts of long, white hairs, develop solitarily or clustered from a single pollen chamber, usually on stunted, markedly shortened catkins which, in cases of heavy infestation, remain hidden in the bud. Distinguished from the preceding species by hairs which only incompletely cover the gall base, hence protruding paint-brush-like from the bud. Q. petraea, robur: Andricus callidoma SG

4a Galls less than 5 mm long, unilocular, spindle of catkin not thickened => 7

4b Galls about 5–10 mm long => 5

5a Galls rotund to globular => 6

5b Galls spindle-shaped, barley grain-like. ± distinctly ridged longitudinally, 6–8 mm long, initially green, later brown; apically framed by a collar of hairs. Usually already before the appearance of this gall with a short stalk attached and locally thickened, often ± bent spindle. Containing a single larva. Q. petraea, robur: Andricus seminationis AG

6a Galls almost globular, vitreous, grape-like, 5–7 mm long; with thick, very succulent wall; unilocular. “Currant gall”. Containing a single larva per gall. Q. petraea, pubescens, robur: Neuroterus quercusbaccarum AG

6b Shiny swelling at the base of the catkin stalk and bending the rest of the catkin (visible at the tip) through 90 degrees; up to 5 mm across; bright green: Andricus curvator SG

6c Galls rotund, 6–10 mm across, multilocular. With many, densely standing, unequal, edged, obtusely acuminate, on top red, viscous, 3–5 mm long appendages. Rachis shortened, bent and thickened. Anthers absent. Not dropping. Containing one larva per chamber. Q. petraea, robur, frainetto: Andricus grossulariae AG

7a Galls glabrous, sometimes either with a tuft or collar of hairs, or only locally loosely pubescent => 11

7b Galls completely, or on major part pubescent or uniformly and pubescent => 8

7c Solitary galls or in small groups of 2‒4; globular, 1.7 mm in diameter, surface initially green becoming grey-brown, covered with small tubercles or projecting spines, and many white hairs of varying lengths: Andricus paradoxus
SG

8a Galls develop on receptacle => 9

8b Galls develop from pollen loculi. The remains of the anthers rest on a bulge. Galls bearing two distinct longitudinal ridges on each side meeting below the tip ± egg- or cone-shaped, about 2 x 1 mm, with a broad base attached to the bulge, initially green-yellow, later brownish, thin-walled, unilocular and uniformly covered by short, obliquely distant, pale yellow hairs. Not dropping to the ground. Containing a single larva. Q. petraea, pubescens: Andricus amenti SG

9a Galls covered by distinctly distant, gradually tapering, slender hairs => 10

9b Galls densely pubescent with short, rough, apically ± club-shaped, translucent, broadened hairs giving the gall a vitreous appearance. Galls ± cylindrical; rounded at both ends, base somewhat broadened, about 4 mm long and 2 mm thick, green or ± reddish. A single larva. Q. petraea, robur: Cynips divisa SG

10a Gall egg-shaped, acute, up to 2 mm long, initially green, later pale brown, uniformly occupied by rigid, distant whitish hairs. Sometimes with several in the clusters of hardly distorted catkins; occasionally framed by some anthers of the same flower. Catkins remain attached to the plant until emergence of the wasps. Containing a single larva. Q. petraea, robur, pyrenaica: Andricus foecundatrix SG

10b Gall egg- to cone-shaped, 2–3 mm long, 1 mm thick, red-brown; the basal, covered, part glabrous, the apical part covered with rather long, yellow to brown hairs; laterally often with dried perianth; up to 1–3 cm of the markedly shortened rachis, ± protruding from the bud, on which the stunted anther fascicles form a bottle brush-like cluster. Occasionally the catkin does not protrude from the bud, however the spreading scales aid recognition of the enclosed parts. Containing a single larva. Q. pubescens, pyrenaica, cerris: Andricus solitarius SG

11a Galls with smooth and dry wall, ± bifid or oblong- to egg-shaped, sometimes locally pubescent, usually smaller than 2.5 mm => 13

11b Galls glabrous, often with only slight, but always distinct, elevated, irregular, often interrupted and converging longitudinal striae. Rachis ± changed; dropping => 12

12a Galls oval to wide lemon-shaped, 3–4 (5) x 2–3 mm, initially greenish, the exterior fleshy and glabrous, later red-brown and dry. At the base of the gall are several anthers and remains of the perianth. A single larva. Q. petraea, robur: Andricus quadrilineatus AG

12b Galls similar, about 3.5 mm across. Quercus spp.: Andricus flavicornis AG

12c Pfützenreiter recorded the early glabrous, smooth- and thin-walled oval, about 2 x 1 mm long galls of Neuroterus albipes SG

13a Galls generated by receptacle => 15

13b Galls very small, developing from a single anther, or even a part of it, attachment broad-based => 14

14a Galls only 1–1.5 x 1 mm, green to yellowish, locally sometimes reddened, glabrous; basal part stalk-like or sometimes egg-shaped or almost globular; the about equal upper, cone-shaped parts with a paler ridge, consisting of remains of the pollen chambers. Containing a single larva. Q. petraea, pubescens, robur, pyrenaica. Neuroterus politus AG

14b Gall ± egg-shaped, about 1.5 (2) mm across, initially green, later yellowish-grey, eventually brown, glabrous or with several short, white, deflected hairs at base. Protruding from the filament; remains of pollen chambers usually unrecognizable. Containing a single larva. Q. petraea, robur: Andricus glandulae SG

14c Gall oblong- to egg-shaped, 1.5–2 mm long and about 1 mm in diameter. The dark ridges, remains of the anthers, are distinct on the gall. Surface glabrous, just below the apex are a number of white hairs about 1 mm long. The yellow-brown galls are inconspicuous among the mature anthers, but may nevertheless be present in large numbers, simultaneously with the AG. Q. iberica, petraea, robur, pubescens, pyrenaica: Andricus quadrilineatus SG

14d The filament is modified into an obpyriform, short hairy, 2 mm long, thin-walled, unilocular gall that apically seems to bear a small cap. Q. petraea, pubescens, robur: Andricus floridus SG

15a Galls slender egg-shaped, with distinct apical wart; inconspicuous, 1.5 mm across, initially green, later yellow-brown, glabrous or with an apical tuft of short, fragile hairs; situated on the receptacle and usually enclosed by normal anthers. Catkins developing normally; dropping after emergence of the adults. Containing one larva. Q. petraea, robur, pyrenaica: Andricus malpighii SG

15b Gall ± oblong-ovate, thin-walled, 2–2.5 (3) x 1.5 mm, greenish to yellowish, with brown tip, at base with collar of white to brown hairs; surface finely longitudinally striated, glabrous or sparsely occupied by short, appressed hairs. At base of stunted catkins, emerging from the receptacle, ± visible just above the bud scales. Containing a single larva. Q. petraea, robur: Andricus solitarius SG

Deciduous oaks, on acorns or acorn cups

1a Galls only on acorn cups => 4

1b Galls on acorns, including cup, or on developing flowers => 2

1c Very small (3 x 2.5 mm) ovoid gall, slightly bent at tip, glossy, glabrous, straw-coloured, hidden between the scales of the cupule; acorn stunted. Q. lusitanica: Andricus nobrei ?G

2a Galls on acorns only => 3

2b Ovary and cup adnate in the developing flowers producing a uniform large fleshy mass pea-size to even hazelnut size, surmounted by the converging cup rims and centrally bearing a stick-shaped thickened style. Side- and upper parts of the cup with many green and succulent red scales, so that the gall is distinguished by its red colour from the similar looking healthy acorns. In the ovary tissue are several, ± egg-shaped chambers each containing a single larva. Q. petraea, robur, cerris: Pseudoneuroterus saliens SG

3a Acorn remaining small, externally otherwise not changed. Hardened seed scale without internal embryo, but with a round cavity containing a round, woody, single-or multi-chambered inner gall. Each chamber with a single larva. Q. petraea, pubescens, robur: Unidentified gall wasp

= From the Iberian Peninsula, but also from NL the gall midge Dasineura squamosa has been recorded on Quercus robur. The larvae develop in atrophied acorns. The same holds, but from Franxe and the Netherlands, for the midge larvae of Contarinia cf. aprilina

3b Acorn remaining small and completely enclosed by cup. Containing one egg-shaped gall, 5–6 x 2.5–3 mm, with a single larva. SG unknown. Galls infected by inquilines are multi-chambered. ‒ Comp. next lead. Q. ? faginea, petraea, pubescens, ? pyrenaica, robur: Andricus legitimus AG

3c Seed scale or cotyledons, rarely the embryo, with several or often many, hard, ± egg-shaped chambers, up to 3 mm long. Development of affected acorns sometimes only slightly stunted, but ± crookedly; usually smaller, sometimes ± curved or only locally swollen. Early infected acorns usually do not protrude from the upper margin of strongly narrowed cups. Each chamber containing a single larva. Q. petraea, pubescens, pyrenaica, robur: Callirhytis cf. glandium AG

= It is uncertain whether the polyphagous and frequent acorn weevil Curculio glandium, similar to Curculio nucum on Corylus, is responsible for the facultative development of “kaptocecidia” after oviposition on suitable acorns.

4a Galls laterally on the acorn cup; SE-Europe => 5

4b The galls develop in early summer from the base of the acorn cup, growing between the ± malformed acorn and the wall of the cup. Base obtuse cone-shaped with broad apical part; 15–20 mm high; at the base 18–25 mm across, initially green and sticky, later grey-brown and dry; with about 5–8 strongly protruding, ± interrupted longitudinal ridges or wings. At top is a narrowed rotund opening, widening conically into a cavity, separated by a thin cross-wall from a smaller basal chamber, containing the globular 3–5 mm long, single-chambered inner gall, attached only at a single point. “Knopper gall”. Containing a single yellow larva. Q. robur, more rarely faginea, x hispanica, macrolepis, petraea, pubescens, x rosacea: Andricus quercuscalicis AG

= Four inquiline Synergus species have been recorded from knopper galls: S. gallaepomiformis, pallicornis, umbraculus, and pallipes

= Furthermore the tortricid Pammene fasciana has been recorded

5a Galls developing isolated on the distinctly recognisable acorn cup => 7

5b Galls to a large extent enclosing the acorn cup => 6

6a Galls arising externally at the base of the cup; cross section similar to a compact double-T beam. Woody, brown-red, glossy, sticky; up to 25 mm high and 20 mm wide. Basal dilatation semi-globular bent downwards, covering cup and under part of the acorn; variously cleft at the margin. The narrowed, but broad central part with mortar-like cavity and smaller, thin-walled inner gall, attached at one point. Upper enlargement broadly disc-shaped, the central part elevated, running into a flat, ± lacerate rim. Containing a single larva. Q. petraea, pubescens, robur, frainetto, etc., also evergreen oaks: Andricus dentimitratus AG

6b Base body of the gall mounted laterally on the acorn cup like a thick, red disc which bears on the outside many, 2–3 (4) cm long, thick filamentous, branched, acuminate appendages. In the middle is a thin-walled inner gall, up to 5 mm long, which is subdivided by a cross wall. “Medusa-head gall”. Containing a single larva. Q. petraea, pubescens, robur, frainetto, pyrenaica, lusitanica, cerris and other species, as well as evergreen deciduous, oaks: Andricus caputmedusae AG

6c Acorn gall, woody, one-chambered, subcylindrical, 4–7 mm high, 5–9 mm wide, slightly attenuate and rotund at attachment, more or less flattened and with a central navel apically. Half-way up its height or higher is a little crown with short but tight reddish hairs. Q. lusitanica: Cynips fortii ?G

7a Galls with variously shaped appendages, multi-chambered => 8

7b Appendages lacking; lemon-shaped to almost rotund, 5–6 mm high, ± 5 mm thick; glabrous or appressed silky pubescent, initially green or red, brown at maturity. Single or with several on the rim of the acorn cup. Containing one larva. Q. petraea, x hispanica, pubescens, robur: Andricus superfetationis AG

7c Hard spherical structure, limited at both poles, 6–8 mm across, one-chambered, surface green, covered with abundant white-yellowish or brownish hairs with length of about 6–10 mm. The whole structure resembles a large cotton ball of 20–30 mm across. Andricus theophrasteus ?G

7d Large blunt-conical gall (20 mm high, 20–25 mm wide at base and the upper part 11–13 mm wide; provided with two basal envelopes of appendages of about 15 mm long and one corolla of shorter and more irregular appendages around the apical opening. This opening corresponds with a conical cavity situated above the inner gall. Surface initially violet coloured and sticky becoming brownish at maturity and losing its sticky substance. Q. lusitanica, pyrenaica: Andricus pictus AG

8a Appendages 4–8 mm long, straight, spiny, each spine tipped with a red, sticky knob; standing in a regular and dense pattern. Gall rotund, cherry- to walnut-sized, pale yellow, thick-walled. Containing one larva per chamber. Q. petraea, pubescens, robur, frainetto and other deciduous species. “Hedgehog gall”: Andricus lucidus AG

8b Gall on acorn cup, often enclosing immature acorn; woody ovoid and radiating blunt rectangular spines, sometimes with longitudinal striations; up to 15 mm total diameter (body of the gall up to 10 mm, spines up to 5 mm long); bright green and sticky at first, later red, then brown and hard: Andricus grossulariae AG

8c Appendages 2–4 mm long, situated in circles; almost cylindrical, irregularly curved, the upper half red, sticky, acuminate. Gall rotund, 10–25 mm across, green or red, later brown, glabrous, woody. Containing one larva per chamber. Q. petraea, pubescens, robur: Andricus seckendorffi AG

Quercus cerris – turkey oak

Quercus cerris, on stems, branches, twigs or shoots
(For galls developing from latent buds on stems, often directly on the bark, see Section B)

1a Galls on various sites on axial parts below inconspicuously disfigured shoot tips => 6

1b Galls develop from shoot tips or on severely stunted short shoots => 2

2a Gall ± barrel- or egg-shaped; ± considerable size, often provided with some scale-like- or ± normal leaves => 3

2b Internodes stunted, short. Young leaves in tufts, brittle along the thickened veins. Several yellowish-white jumping larvae. Also on Q. petraea, robur, etc.: Contarinia quercina

2c Gall irregular thick disc-shaped, up to 15 mm wide, developing from the severely stunted and widened shoot tip and broadened leaf cushions. Gall hard, strongly pubescent, sometimes deeply grooved. In the central part of the upper side protrude many yellowish one-chambered inner galls, originating at the leaf base. The complete gall is ± completely surrounded by a tuft of many reduced, often heavily disfigured leaves and overtopped by some appendages. Each chamber containing a single larva: Andricus multiplicatus SG

2d Gall develops on the shoot opposite a developing leaf, causing retardation of this leaf’s development. This gall causes a hollow swelling of the shoot 5‒6 mm thick at a junction with a leaf petiole, although the axis of the shoot is not distorted. Gall surface uneven. An elliptical inner cell with a thin, brown wall is situated within the gall’s inner chamber: Plagiotrochus marianii AG

3a Galls one-chambered => 4

3b Gall multi-chambered up to 15 mm long, rotund- to oblong-oval, greenish, weakly pubescent, woody; large jar-shaped, with wide open cavity, above the basal half with many egg-shaped inner galls. Galls, especially in the upper part, with almost chaffy scale-like leaves. Each chamber containing a single larva: Andricus cydoniae SG

4a Galls less than 10 mm long => 5

4b Shoot apex shortened, club-like, swollen. Galls up to 20 mm long and 10 mm wide; in the middle with an oblong, eventually open cavity, on the bottom with a small oblong-oval inner gall. The ±normally developed leaves on the gall close to one-another. Containing a single larva. Also Q. lusitanica: Andricus inflator SG

5a The rotund-oval gall, 3–5 mm across, initially green, at maturity brown, originates on the axis of a longitudinally completely stunted short shoot and bears on its tip bud-like arrangements of leaf rudiments. Containing a single larva: Andricus gemmeus SG

5b Galls in small twigs, located apically; the host bud gall is integral to the twig as well as the larval chamber and thus typically a tiny swelling is visible where the larval chamber is located. Rarely the gall is spherical, 3–5 mm across; may also be found on petiole and leaf midrib: Synophrus hungaricus ?G

5c Galls 6–8 mm long, ± globular or pear-shaped, weakly pubescent, hard, one-chambered; on the outside with 2–3 (4), ± normally developed as well as scale-like leaves. Inner gall egg-shaped, brown, hard, only free at apex. Connected to the outside by a thin canal. Containing a single larva. Andricus singularis AG

6a Galls usually well delimited, ± distinctly protruding or bark with groove-like, rimmed depressions => 7

6b Young twigs swollen on all sides, 2–4 times the normal breadth over a length of 10–50 mm. Gall surface glabrous or ± tuberculate. In the woody part of the gall are many oblong-oval chambers, which are at right-angles to the pith and each containing a single larva: Pseudoneuroterus macropterus AG

7a Bark with shallowly bulging, rimmed depressions, containing gall causer covered by a shield => 12

7b Galls protruding from the bark of solitary twigs or thinner branches, ± well defined => 8

8a Single galls less than 5 mm across => 9

8b Gall up to 15 mm long, short-stalked, rotund, initially pale green and ± with short felt-like pubescence, later on brownish and glabrous, thick-walled, dry and hard; predominantly on thin, not disfigured twigs; ± embracing these. Occasionally many groups up to 70 mm long, mutually flattening one-another; sometimes shortly tuberous, up to walnut-size. A large cavity with one, more rarely, two separated rotund-oval inner galls, attached only at base. Containing a single larva. Aphelonyx cerricola AG

= Inquiline cynipids: Saphonecrus undulatus and/ or Synergus flavipes.

9a Galls with tough or membranous wall, dry at maturity, without separate inner gall => 10

9b Up to about pea-size, succulent to cartilaginous one-sided swelling of young shoot, bent at infestation site. Containing an eventually detached inner gall with a single larva: Andricus curvator SG

10a Galls about 2–3 mm across; appearing solitary or in small irregular groups on young twigs => 11

10b Many galls in groups protruding on all sides from the bark of stronger twigs or thinner branches. Single gall ± egg-shaped, up to 5 mm long, attached with an acute base; pale green to reddish. Surface viscose, oily. Each chamber containing a single larva: Dryocosmus cerriphilus AG

= Inquiline gall wasps: Saphonecrus haimi, undulatus and/ or Synergus variabilis

11a Gall elongate spindle-shaped, 2–3 mm long; attached over its length; green, later on red-brown; one-chambered. Often several to many, separated, in the outer bark of not thickened young shoots. Each gall containing a single larva: Pseudoneuroterus saliens AG

11b Single galls rotund, flat, nodule-shaped, up to about 2 mm wide; often with several on the nodes, sometimes appearing on the internodes at base of one year old ± shortened and swollen shoots. Solitary galls form sometimes only a barely recognisable nodule. Containing a single larva: Andricus quercusradicis SG

11c Galls rotund to elliptical, up to 2 mm long, wall very thin. In leaf axils of young shoots, but not in buds. Containing a single larva. Andricus quercuscorticis SG

12a Bark with bulging thickened ridge surrounding depressions. Below a rotund-oval convex shield, about 1.6–2 mm wide: Asterodiaspis variolosa

12b Similar, but less conspicuous malformations. Shield flat lid-shaped, rimmed, 1–2 mm wide: Diaspidiotus zonatus

Quercus cerris, on buds

1a On terminal and lateral buds of young shoots => 3

1b Galls on older branches or stems, emerging from adventitious or dormant buds => 2

2a Gall transversely egg-shaped, up to 2 mm long, with finely granulate surface, greenish, also ± reddened or crimson-violet. Wall very thin, leathery. Galls usually with several together on older branches or stems. Containing a single larva: Cerroeuroterus aggregatus SG

2b Galls egg-shaped to cylindrical, up to 3 mm long; rounded or weakly depressed at the tip, dense- and short velvet-like pubescent; initially red, later dark violet; thin-walled, often surrounded at base by bud scales. A large chamber containing a single larva: Cynips quercusfolii SG

3a Galls completely or partially transformed into closed galls of distinct shape. Gall wasp galls => 7

3b Buds swollen and ± not opening => 4

4a Galls on young shoots, caused by gall midge larvae => 5

4b Lateral buds or perennial shoots swollen: Aceria cerrigemmarum

5a Buds usually distinctly opened => 6

5b Buds enlarged and slightly swollen, up to 10 mm long and 5 mm in diameter; usually not opening and surmounted by the free tips of the scales; only occasionally developing further together with the smallest, irregularly developed leaves. Larvae bright yellow: Contarinia quercicola

6a Galls often very similar to the preceding ones. Buds enlarged and swollen, of the same size as the preceding one, but often slightly opened. Several orange-red to red larvae: Arnoldiola dryophila

6b Malformation similar. Containing a single larva: Unidentified gall midge

7a Single galls about 1.5–6 mm long. Wall leathery or succulent. Several galls are often partially coalesced; however, ± deep furrows indicate the separate galls => 11

7b Galls often more than 6–10 mm long, uniform in outline. Wall thick, succulent or wood => 8

8a Galls 8–15 mm long, uniform in outline. Wall tough and woody, dried out. Inside is a larval chamber => 10

8b Galls usually larger than 15 mm => 9

8a Gall 15–30 (40) mm long; rotund to flattened oblong-oval, initially whitish, later on brownish, tuberculate, nodule-like. Wall succulent, spongy. Inside are many hard larval chambers. Mature in 6; not dropping off. The soft parts dry out up to the separate chambers after the adults have emerged. Each chamber with a single larva. “Oak apple: Biorhiza pallida SG

9b Galls up to 20 mm across; rotund. Wall hard, woody, provided with ± wart-like tubercles. Mature in autumn. The central chamber, surrounded with a protective layer, containing a single larva: Andricus infectorius AG

9c Gall oblong-ovoid (1.5 x 1 mm), thin-walled, terminally with a small curved apex, one-chambered, covered with long erect hairs; usually solitary in a leaf axil: Callirhytis meunieri SG

9d Gall conical, with dense and short pubescence: Andricus tomentosus AG

10a Gall broadly coalesced with twig; variously shaped, usually rotund, (6) 10 (15) mm across; initially green, also bark-coloured to dark grey; glabrous or with minute warts. The thick wall with an outer, greenish bark layer and a thicker, inner ± whitish woody tissue. The central chamber containing a single larva: Synophrus politus SG

10b Gall spherical, 4–5 mm across, surface with some little whitish protuberances. Synophrus pilulae SG

10c Gall in small twigs, located apically; a tiny swelling is visible where the larval chamber is located; rarely the gall is spherical, 3–5 mm across. Occasionally also on petiole and midrib: Synophrus hungaricus SG

10d Gall almost spherical, 6–10 mm across; solitary or often with several together. Surface reticulate, rough, ± pale grey. Wall woody, in cross section uniform radially striate, rust-brown, only the protective layer paler close to the larval chamber situated at the attachment point. Containing a single larva. “Cola-nut gall”: Andricus lignicolus AG

10e Gall globular, 5–10 mm across, covered with tubercles: Andricus caliciformis AG

11a Galls 2–3.5 mm across, one-chambered, if in clusters, then not coalesced => 12

11b Single galls rotund-oval to conical, about pea-size, up to 6 mm long; glabrous or ± warty, pale green, partially violet-red, initially glossy, with very sticky coating, later on dull. Inside spongy-succulent, brownish; with usually several, hard-walled, brighter inner galls. Two to several galls coalesce often into irregular, cherry-size structures, more or less distinctly showing by furrows the number of participating galls. Each chamber containing a single larva: Chilaspis mayri SG

11c Gall thick-walled and woody, bright brown, sticky when fresh. From a basal disc of 10 mm in diameter, embracing the twig, rises a truncate cone which ends in an apical navel. Total height 8–10 mm: Andricus mitratus AG

11d About 3–4 mm long, sometimes coalesced into larger structures. The unilocular, solitary gall, 2.8 mm x 1.3 mm, usually hidden by the bud scales, is barely visible. Gall surface smooth, and medium to pale brown or orange-brown. The gall is usually twice as tall as broad, with lateral longitudinal ribs, the tip of the gall tapering into a blunt irregular point: Andricus hystrix SG

11e Gall subglobular (20–22 x 18–20 mm), hard, smooth, conical at base, the distal region flattened and with 7–10 blunt appendages. Larval cavity rotund and large. Andricus bulgaricus AG

12a Galls developing from the centre of the bud => 13

12b The galls develop from the inside of the soon unfolding bud scales. Gall oblong-oval, 1.5–2 mm long, yellowish, almost glabrous, thin-walled. Usually 2–3 galls per bud. Each containing a single larva: Cerroneuroterus obtectus SG

13a Gall egg- to barrel-shaped, round in cross section, 2–3 mm across, glabrous, solitary or many per bud => 14

13b Gall similar to an apple seed, flattened in cross section, attached with rounded base; upper part acute conical; 3–3.5 mm high, brown, with paler tip. Surface finely warty, rugose; with upwardly directed hairs which are more dense towards the tip. Corolla-like surrounded by several ± smaller leaves. Containing a single larva: Andricus cryptobius SG

14a Galls barrel-shaped, glabrous, up to 2 mm long and 1 mm in diameter, narrowed upwards, with obtuse apical part, usually solitary, rarely paired, only showing its tip => 15

14b Galls rotund-oval, about 2–3 mm long and ± 2 mm in diameter. Surface finely granulated, yellow-brown to grey. Usually several in a terminal- or lateral bud on previous-year shoots; rarely solitary, in that case larger and oblong-oval. Containing a single larva: Andricus kollari SG

15a Thin-walled bud gall, 2‒2.5 mm long, pointed, usually single, lower half covered by bud scales. Its surface is ± velvety-glossy greyish brown; the very tip often has a small black spot: Andricus improprius SG

15b From almost identical galls, but developing 1–3 per bud, and, contrary to the preceding gall, apically mucronate: Andricus lignicolus SG

Quercus cerris, on leaves

1a Galls open or connected externally by a small, only point- or slit-like entry, sometimes hidden and rarely visible to the naked eye; curls, marginal folds or rolls, or erinea. Galls caused by fungi, mites or insects, gall wasps excepted => 31

1b Galls closed on all sides (galls usually caused by gall wasps) => 2

2a Galls on the petiole or on subsidiary veins. Larvae in gall chambers => 11

2b Galls in or on the leaf blade or on the main veins, sometimes attached terminally => 3

3a Larvae living in closed cavities until maturity. Gall wasp galls => 4

3b Petiole stunted, conspicuously swollen, sometimes curved. Inside a caterpillar, producing short ellipsoid mine next to the midrib, this for the most part falling out later on: Heliozela sericiella

4a Galls of various shape; with broadened or narrowed base attached to the leaf, or even stalked => 6

4b The rotund- or oval galls are situated, inside the petioles or veins, surrounded by host tissue. Usually several galls coalesce into sometimes ± bulged swellings; on the venation mainly conspicuous on the underside (in immature stages visible galls sometimes ± similar, on both sides of the leaf blade => 5

4c Large spherical gall, 10–30 mm across, succulent, surface slightly irregular. Dropping off with leaves. Containing a single larva: Cynips quercusfolii AG

5a Single gall rotund- to oblong ovoid; one-chambered 2–3 (4) mm across. Usually several galls are variously coalesced to ± expanded bulging swellings. Solitary galls occasionally also in the main lateral veins. Each gall with a single larva: Andricus quercusradicis SG

5b In similar, sometimes more markedly bulging galls developing on Q. cerris also are the larvae of Andricus testaceipes SG

6a Galls directly attached to the petiole or leaf blade veins => 8

6b Galls terminally attached to the midrib, or with a longer stalk to the venation => 7

7a Galls on the stunted tip of the midrib of a usually severely stunted leaf. Gall rotund, about pea-size, glossy and sticky. Containing a single larva: Chilaspis mayri SG

7b Smaller, only about 1.5–2 mm long, ± egg-shaped, pale green to yellowish galls which are distantly sparsely pubescent; usually terminally on main veins with leaf margin often ± emarginate. Containing a single larva: Neuroterus albipes SG

7c Galls usually located on a main lateral vein which leads to the outer edge of a lobe, globular with a short, blunt tip; 5‒8 mm diameter; fleshy. The gall makes a small hump on both sides of the leaf blade. If located at the end of a vein, the gall has a small, curved tip. Pale green, with a pubescent surface. Thick-walled; central chamber large, unilocular: Dryocosmus cerriphilus SG

7d Gall half spindle-shaped to funnel-like, green, glabrous; with long slender drooping stalk attached to the mid-rib; reaching the leaf margin. Containing a single gall: Amphibolips mernyensis ?G

8a Galls usually only on the underside, one-chambered, glabrous => 9

8b Ovoid, about 2 mm long and 1–1.5 mm broad swelling on petioles or, visible on both sides of the leaf blade, on main veins. Initially yellowish, later on brownish, with distant whitish hairs which may be somewhat longer on the upper side; thin-walled; one-chambered. Containing a single larva: Andricus schroeckingeri SG

9a Galls spindle-shaped or flat rotund-ovoid => 10

9b Galls urn-shaped; up to 3 mm long, green to red-brown, longitudinally grooved; terminally flat, with protruding margin. On swollen parts of the midrib often with several together. Containing a single larva: Andricus gallaeurnaeformis AG

10a Galls kidney-shaped, up to 3 mm long, attached to the leaf over the complete length of the gall. Containing a single larva. Also on Q. lusitanica. Galls kidney-shaped, up to 3 mm long, attached to the leaf over the complete length of the gall. Containing a single larva. Also on Q. lusitanica: Pseudoneuroterus saliens AG

10b The full-grown gall, about 4 mm long, laterally flattened, rotund- to oblong-ovoid, yellowish, densely red- to violet-spotted protrudes laterally from the leaf veins. Surrounded by two valves and dropping off. Containing a single larva. “Oyster gall”: Neuroterus anthracinus AG

11a Galls visible on both leaf sides; one chambered => 19

11b Galls visible on only one side of leaf, point-like attachment => 12

12a Galls predominantly on underside of leaf => 13

12b Galls predominantly on leaf upper side, rarely on underside and then on smaller veins. Globular, ± 1.5 mm across. Initially white to green, later on rust-brown, glabrous; densely covered by short rounded tubercles, red at maturity; tough-walled. Often with several together; one-chambered, containing a single larva: Cerroneuroterus minutulus AG

13a Gall distinctly wider than high, ± disc- or kidney-shaped; point-like attachment; one-chambered => 16

13b Galls rotund, about as long as broad; ± thick-walled => 14

14a Galls 4–6– (20) mm across, pubescent or glabrous => 15

14b Galls oblong-rotund, 2–2.5 mm long and 1.5–2 mm broad. White or pale reddish. Surface densely covered with acute, dark red tubercles. Wall hard and thick. Larval chamber large, oblong-oval. Solitary or with several scattered on the underside of the lateral veins; one-chambered. Mature in autumn. Containing a single larva. Unidentified gall wasp

15a Gall rotund-oval, about 1 mm across, with large larval chamber, very short stalked, provided with many, distant, 3–5 mm long, filiform, multi-cellular hairs. Often several coalesced into a wine-red complex. Neuroterus sp. ?G

15b Gall oblong-oval, 4–6 mm across; covered by short, dense stellate hairs, green, later on grey-brown, thick spongy-walled; with one or two transverse-oval larval chambers. Attached to leaf underside with short thin stalk on secondary vein. Containing a single larva: Chilaspis nitida AG

15c Gall similar to the gall of the AG of Ch. nitida, but smaller (1-3 mm) and with a relatively thinner wall. Also on Q. suber: Chilaspis trinacriae AG

15d Gall on apical and accessory buds, rotund, 5–10 (20) mm across, greenish to grey-green, upperside rough because of minute warts. Wall very thick, tough, with a greenish outer- and a somewhat thicker, paler, inner layer. Larval chamber relatively small, with coalesced protective layer on all sides. Containing a single larva: Synophrus politus SG

16a Galls disc-shaped in outline, of various height => 17

16b Galls flat kidney- or bean-shaped, up to 4 mm across; pale green or ± reddened. Often with several together on the underside of lateral veins. Older galls browned, eventually ± rounded; dropping off. “Kidney gall”. Containing a single larva: Trigonaspis megaptera AG

17a Galls flat disc-shaped, rotund, 4–6 mm across; glabrous or with stellate hairs => 18

17b Galls flattened, thick disc-shaped, rotund, 4–5 (6) mm broad, 3–4 mm high, white or ± red, flat above, with slightly elevated centre, margin below curved. Whole surface provided with long silky hairs, which are longer in the centre of the gall and yellow-brown and shorter and whitish towards the margin. Periphery with flat cavities, separated by small plates. Inner part consisting of uniform tissue surrounding a small larval chamber. Containing a single larva: Cerroneuroterus lanuginosus AG

18a Galls up to 5 mm wide, slightly curved upwards at margin, hence flat bowl-shaped; radial striate, with slightly elevated central part. Margin sometimes slightly undulate. Galls yellowish to deep red, glabrous, or with scattered stellate hairs. One chamber containing a single larva: Neuroterus albipes AG

18b Galls up to 6 mm across; brownish-yellow or ± reddened, especially when young. Upperside densely covered with large rust brown stellate hairs; often white-spotted on the margin, underside glabrous. Closely appressed with its entire disc. In cross section a flat, blunt triangle. Containing a single larva in a central larval chamber: Neuroterus quercusbaccarum AG

19a Galls protruding on both leaf sides; however, predominantly only on one side => 24

19b Galls ± globular or pustule-shaped; in about equal amounts on both leaf sides => 20

20a Gall developed as low, up to 2.5 mm wide, glabrous, one-chambered, pustule-shaped swelling of the leaf blade => 22

20b Galls ± globular, to ovoid, one-chambered, ± pubescent; on, or next to, a vein => 21

21a Galls ± oblong-oval, about 2mm long and 1–1.5 mm high, longitudinal axis in the leaf blade, usually next to a main vein and leaf margin emarginate towards the vein. Yellowish to brownish, with distant simple, whitish hairs, thin-walled. Containing a single larva: Andricus schroeckingeri SG

21b Globular gall, 5–8 mm across, pea-size, translucent green, with short stellate hairs, thick-walled, succulent. Attached on the swollen end of a lateral vein. Larval chamber rotund, diameter equals the wall thickness. Containing a single larva: Dryocosmus nervosus SG

22a Larvae in closed chamber where they complete their development; pale with distinctly darker head => 23

22b Larvae lacking conspicuous mandibles, in round pustule, about 2.5 mm wide, very flat with a small wart on upper and on underside. Larvae pale red: Janetia pustularis

23a Leaf blade with one-chambered pustules, about 2 mm across. Containing a single larva with contrasting head. Unidentified gall wasp

23b Similar galls, 5 (6) mm across, on the upper side with radiating striations: Neuroterus numismalis SG

24a Pustule-, conical, cornicular, sometimes bulge-like galls are only apparently closed on all sides. Midge galls => 25

24b Galls oblong-ovoid 2–2.5 mm high, about 1.5 mm wide, with their longitudinal axis at right-angles to the leaf surface; protruding mainly on the upperside, underside only ± half-globular. Closed on all sides, thin-walled, one-chambered, glossy or dull, provided with long, distant stellate hairs and simple hairs in between. Often clustered on hardly stunted, but often ± heavily curled leaf blades. Containing a single larva: Andricus crispator SG

25a Galls in the leaf tissue, on both sides of leaf but developed to different extents => 26

25b Midrib, sometimes also all major veins, with 3–4 mm long, blunt spindle-shaped, predominantly laterally arched, glabrous swellings, sometimes visible on the leaf upperside as rather flat, pale green bulge. Often occurring on the underside on both sides of the midrib in a compact sequence behind- or next to one another and ± mutually coalescing to a varied extent. Each gall containing a longitudinal larval chamber, closed until maturity and later on with a slit-like opening towards the leaf blade. Containing a single larva: Janetia nervicola

26a When mature, only a part of the gall drops off, or opens by valves => 29

26b The gall remains complete, the larval chamber is connected to the outside by a ± thin channel, closed until maturity by a net-like barrier of upwardly directed small hairs => 27

27a Galls more conspicuous on the underside or thick disc-shaped => 28

27b On the upper side cornicular protruding, up to 6 mm high and 1 mm in diameter, ± bent, sometimes provided with some stiff bristle hairs. On the underside with a collar closing the gall exit, with yellowish hairs on the inside. Often many per leaf blade. Containing a pale yellow larva: Contarinia subulifex

28a Upperside ± half-globular; up to 1.5 mm high and 2 mm broad, yellowish, glabrous. On the underside with thin, ± bent tube up to 2.5 mm long; exit closed by hairs on top. Wall hard. Containing a single yellow larva: Dasineura tubularis

28b Rotund to kidney-shaped gall on the underside, up to 6 mm wide and 2.5 mm high, provided with distant, yellow or grey, hairs. On the upperside a sparsely pubescent disc, surrounded by a slightly bulged rim with a central ± fish trap-like barred pore. Larval chamber expanded, running into the pore spirally. Often many per leaf blade. Containing a single larva: Dryomyia circinans

29a Galls up to 3 mm across => 30

29b Gall flattened, hard, almost woody, up to 5 mm across, with a thick (2–3 mm) base, slightly convex in the middle with a small tubercle; on the leaf upperside a round yellowish pustule, the middle conical, provided with some hairs. The under part, a lid which drops off when mature, is felt-like pubescent. The larval chamber is situated at base in the thickened disc. Containing a single red larva: Janetia homocera

30a Upper part with broad base, acuminate-conical; about 2 mm high, glabrous, yellow-brown. The somewhat narrower, on the underside only weakly protruding basal part is flat, disc-like, with central channel and densely covered with distant, fine yellowish hairs. Between both parts is the elongated larval chamber. At maturity the basal part becomes lid-like detached and drops off. Containing a single orange-red larva: Janetia cerris

Inquiline gall wasps: Saphonecrus haimi and Synergus variabilis

30b Leaf blade usually with several rotund, somewhat darker coloured, differently appearing, weak bladder-like swellings. On the upperside ± lenticular, glabrous, with central, point-shaped tip. On the underside a densely pubescent, central valve-like opening in autumn. Containing a single larva: Janetia szepligetii

= From GR, southern I the gall midge Janetia plicans has been recorded in crowded young leaves, containing a white larva

31a Galls situated in leaf blade => 34

31b Galls on leaf margin => 32

32a Leaf margin without conspicuous thickening, variously folded downwards => 33

32b Margin of expanded leaves narrowly tubular and rolled upwards between the lobes. In the hardly discoloured, clearly thickened ± leathery-brittle roll are one to several white larvae: Macrodiplosis roboris

33a Margin of the young leaves with sometimes several narrow, scale- or mussel-like downward, rarely upward, indentations. The respective vein slightly thickened and discoloured at the site of infestation. Each gall initially containing an aphid: Phylloxera coccinea

33b Margin of the leaf lobes broadly folded downwards. Outside of the gall slightly thickened, often marbled. Containing usually only a single yellowish-white larva per gall: Macrodiplosis pustularis

34a Leaf blade with smaller to larger, up to bladder-like swellings => 35

34b Leaf blade folded upwards over the midrib, the affected venation, especially of the basal part, thickened, abnormally pubescent. Unidentified gall midge

35a Usually upwardly directed protrusions several mm wide => 36

35b Small upward protrusions; containing a froth-covered nymph in the cavity on the underside. Trioza sp.

36a Leaf blade bulging upwards, swollen. In the depressions abnormal felt-like pubescence, composed of longer, ± twisted, and shorter, club-shaped or cylindrical hairs: Aceria cerrea

36b Leaf blade with 4–8 mm wide, rotund, slightly protruding upward archings, rarely also arched downwards. Infections initially ± pale- to grey-green, later on browned. Developing asci at maturity: Taphrina caerulescens

Quercus cerris, on male inflorescences (catkins), acorns and acorn cups

1a On male catkins => 4

1b On acorns and acorn cups => 2

2a Acorn and cup severely stunted, galls inside the only slightly disfigured organs =>3

2b Laterally on acorn cup a thick red disc is attached with many thick-filamentous, up to 45 mm long, ± curved and finely branched, acuminate appendages on its margin and upperside. In the middle of the disc is a thin-walled, up to 5 mm long, transverse inner gall. Often with several together forming a cluster up to 10 cm large. Containing a single larva: Andricus caputmedusae AG

3a In the female bud the ovary and cup coalesce into a uniform, pea- to almost hazelnut-size succulent mass, overtopped by the converging cup margins. The swollen style protrudes stalk-like from the remaining opening of the cup. The cup is provided with many succulent green and red scales, especially on the sides and above. Especially conspicuous as the red colour differs from the normally developing acorns. Inside the ovary tissue several ± egg-shaped larval chambers. Each containing a single larva: Pseudoneuroterus saliens SG

3b Acorn may be infected during various developmental stages. In the seed coat and in nutritive tissue usually many hard galls develop, up to 2 mm long, oblong. Development of acorn depending upon the stage of infestation ± severely stunted. Galled acorns sometimes completely hidden in the cup, in other cases, seen from the outside, hardly different from healthy ones. If many larval chambers are developed ± bulging; occasionally bursting open: Callirhytis erythrocephala AG

4a Gall wasp galls; galls glabrous, sometimes sparsely pubescent => 5

4b Complete catkin stunted caused by gall midges. Larvae whitish: Contarinia cerriperda

4c On blossoming catkins cherry- to even walnut-size, rotund, ± chequered, cotton wool-like balls, consisting of many, up to 3 mm long, oblong, dense long-haired, two-chambered galls developed from anthers. Depending on the number of single galls the surface of the gall is chequered facet-like. Hair in the middle of the facets dirty crimson-red, on the margin whitish. Containing a single larva per chamber: Chilaspis nitida SG

5a Galls at most 2.5 mm long => 8

5b Galls larger than 5 mm => 6

6a Outer wall succulent; galls originating from receptacle, up to about 7 mm across, one-chambered. Rachis normal => 7

6b Outer wall tough. Galls about 10 mm long and 6–8 mm wide, ± glabrous, green, yellow or red; often several together in a 20–40 mm long cluster. Single gall urn-shaped, middle part swollen, base narrowed, apex running into a deflected, undulate margin. Upper half wide open, in the under half tissue several oval larval chamber each containing a single larva: Andricus lucidus SG

7a Galls ± rotund-oval to inverted pear-shaped with conical apex; 6–8 mm long, weakly haired, rather glossy, green, red later on, eventually brown-red, similar to a red currant. Conical apical part hollow; a cross wall closes a cavity below, which containing a semi-woody inner gall. Containing a single larva: Andricus grossulariae AG

7b all tube-shaped, 4–6 mm long and 1.5–2.25 mm wide; often bent over at right- angle; slightly narrowed towards the apex, apically rounded or uneven two-lipped. Initially green, later on reddish to brown; indistinctly longitudinally grooved or ± rugose; short pubescent. A thick-walled, yellowish-white inner gall in the basal cavity, separated by a cross wall from the oblong tubular cavity of the apical part. Containing a single larva: Andricus vindobonensis SG

7c Galls rotund to pear-shaped, 6–10 mm high and 5–7 mm in diameter. Above the ovoid larval chamber is a cylindrical cavity which opens at the gall apex: Andricus grossulariae AG

8a Development of catkin spindle not conspicuously stunted, fully elongating from the bud. Galls one-chambered, emerging from an anther => 10

8b Rachis severely stunted, not- or only slightly elongated => 9

9a Catkin usually already stuck in the opening bud. Gall emerging from the anther; egg-shaped or conical towards apex, 2–2.5 mm high, dirty-yellow, glabrous, glossy. Usually with many in the open flower bud. Each gall containing a single larva: Andricus burgundus SG

9b Rachis severely stunted, sometimes hidden in the fully opened bud, or the densely clustered galled flowers protrude from the opened catkin bud on a stalk like a bundle of bottles. Galls emerging from the receptacle; egg-shaped, 2–2.5 mm long, red-brown. The basal part, covered by the flower parts almost glabrous, the apical part provided with rather long hairs. Often 2–3 galls terminally on the slightly swollen rachis. Each gall with a single larva: Andricus solitarius SG

10a Galls glabrous, ± egg-shaped, the upper half ± rounded to acuminate cone-shaped. 1–1.5 (2) mm long and 1 mm thick; greenish, brownish at maturity, dull, glabrous; wall very thin. Developing from one of two anthers, the remains of the second anther often laterally on the upper part of the gall. Filaments reduced and therefore gall attached with a broad base. Containing a single larva: Andricus quercuscalicis SG

10b Galls one-sided ± flattened, oblong-oval, 1.5–1.75 x 1.25 mm, lemon-shaped acuminate above. Initially orange-yellow, dull; later on brownish, setose; thin-walled. The shortened stamens bearing at base the remains of ± withered second anther. Containing a single larva: Cerroneuroterus cerrifloralis SG

10c The gall is formed from a single hypertrophied anther. The mature gall is 1.5‒2.0 mm long. The anther curve around the side of the gall, forming a grooved mark which runs up one side of the gall for 60% of its height. The gall is covered with a dense coat of silvery hairs. The gall is green when young, becoming golden brown when mature: Cerroneuroterus cerrifloralis SG

Evergreen oaks, Quercus coccifera, ilex, lusitanica and suber

Evergreen oaks, on branches, twigs or shoots

1a Galls not terminally situated => 3

1b Terminal galls on twigs => 2

2a Irregular woody pea-size thick walled swelling of terminal shoot bearing remnants of leaves and buds. Containing one or two oblong cavities each with a single larva: Andricus singularis SG

2b The internodes are stunted, the clustered leaves are changed into a round hazelnut-size mass, or even walnut-size, the inside with many galls. Q. ilex, trojana, crenata, cerris: Andricus multiplicatus SG

2c Terminal ovoid swelling, hard, woody, multi-chambered, hazelnut-size. With terminal exit hole and may bear several leaves. Q. suber, cerris: Andricus cydoniae SG

3a On Q. ilex => 5

3b On Q. suber => 4

3c Spindle-shaped woody swelling of basal or subterranean parts of twigs. After the adults have emerged the galls are riddled with exit holes. Q. coccifera, ilex: Plagiotrochus kiefferianus AG

3d Large subglobular woody one-chambered gall embracing the twig. Q. ilex, suber, crenata: Aphelonyx cerricola AG

3e Weak one-sided broadly attached conical swelling on bark of young twigs, on petioles and leaf blade, 2 mm across with apical exit hole leading to the gall chamber. Also other plant organs, buds, catkins may be infected. Containing yellowish larva. Q. coccifera, ilex, suber: Contarinia luteola

3f On the bark of the stem, 10–20 years old, hardly visible bump, 6 mm long, 4–5 mm wide, same colour as bark, which does not tear; each bump corresponds with an internal gall, woody, elliptical, 4 x 2.5 mm, usually oriented parallel to the stem surface. Often several galls together which may coalesce. Q. ilex, suber: Plagiotrochus marianii AG

3g Irregular swelling of the twigs. 2–3 x 1 mm. Q. coccifera, suber: Andricus quercusradicis SG

3h On Q. coccifera. Cylindrical or elliptical swelling of twig: Plagiotrochus gallaeramulorum ?G

= Inquiline cynipids: Synergus physoceras, Saphonecrus lusitanicus

3i On Q. x hispanica. Multi-chambered swelling. Also on Q. cerris: Pseudoneuroterus macropterus AG

4a Young twig thickened and bent close to the tip with, in the concave part, a woody swelling 6–7 mm long and an ovoid inner gall: Andricus fidelensis

4b Oblong spindle-shaped galls, surface smooth. Contain many gall chambers in pith: Plagiotrochus fonscolombei AG

4c One-sided, one-chambered pea-size swelling: Unidentified gall wasp

5a Weak swelling of lammas shoot: Plagiotrochus razeti SG

5b Weak swelling on a previous year twig: Plagiotrochus yeusei ?G

Evergreen oaks, on buds

1a Galls artichoke-shaped or cauliflower-like, gall midge- or mite galls => 2

1b Five to ten conical glabrous glossy pale red galls, 1.2–1.5 mm across, in opening bud, apex slightly bent; wall very thin. Exit hole close to top at the concave side of gall. Q. ilex, suber: Andricus luteicornis SG

1c Bud galls different => 3

2a Artichoke galls. Conspicuously enlarged imbricated scales envelop an ovoid plurilocular gall caused by yellow-orange gall midge larvae. Q. coccifera, ilex, suber: Phyllodiplosis cocciferae

2b Agglomeration of many stunted buds forming an irregular greenish or reddish cauliflower gall, reaching a diameter of 50–60 mm. Q. ilex, suber: Aceria suberina

3a Gall one-chambered => 5

3b Gall many-chambered, irregular rotund => 4

4a Gall whitish or pinkish, glabrous, succulent, cherry- to walnut-size. Q. ilex, suber: Biorhiza pallida SG

4b Bud transformed into an irregular rotund, very tough bark-coloured gall, 15–30 mm across, woody multi-chambered; glabrous and provided with small tubercles. Gall-chambers ± 2.5 mm, randomly arranged. Q. ilex, suber: Synophrus olivieri ?G

5a Gall one-chambered, thick-walled => 7

5b Gall spindle-shaped, length about 10–15 mm, or ovoid, only 2 mm across => 6

6a Gall body spindle-shaped to conical, about 10–12 (16) mm long and 3 mm wide, thin-walled, hard, with large chamber. Q. ilex, suber: Andricus solitarius AG

6b Gall egg-shaped with two ridges converging to mucronate apex; greenish. Q. ilex, suber, also on Q. cerris: Andricus hispanicus ?G

7a Gall spherical => 8

7b Gall partially embracing base of shoot, 6 mm high, 11 mm wide, 7 mm thick, surface brownish, rough or finely wrinkled, scattered pubescent, very fine; thick-walled, inner gall 3 mm across, situated close to the base. Q. x hispanica: Andricus gracilicornis ?G

8a Thick-walled spherical gall, 12–20 mm across, pale brown, glabrous or with scattered tubercles. Q. ilex, suber: Andricus kollari AG

8b Thick-walled spherical gall, 15–30 mm across, chestnut brown, on its upper part tubercles arranged in a corolla. Q. ilex, lusitanica: Andricus quercustozae AG

= Galls of Andricus insanus strongly resemble those of A. quercustozae but they are permanently viscous (those of quercustozae only when young) and the spines are not arranged in a neat circle, but rather scattered in several circles.

8c Similar gall, 10 mm across, hard woody wall, bark coloured. Q. ilex, libani, trojana, mongolica, suber, crenata: Synophrus politus SG

8d Similar gall, 10–20 mm across, some galls are irregular in shape and only 5–10 mm across: Synophrus hispanicus AG

Evergreen oaks, on leaves

1a Gall on leaf blade => 4

1b Gall on petiole or in midrib => 2

2a Gall wasp gall => 3

2b Gall midge gall. Small conical swelling on the petiole, green or straw-coloured; apical exit hole, pubescent up to the mid-length; the base surrounded by a circular area of 2–3 mm in diameter. Q. ilex, suber: Contarinia luteola

3a Kidney-shaped to spindle-shaped, one-chambered swelling emerging from a crack in the vein, initially pale green, later on reddened; 2–2.5 x 1.5 mm. Q. ilex, suber; also on Q. cerris: Pseudoneuroterus saliens AG

3b Ovoid gall 2 mm long, attached to the midrib, which makes two valve-like protrusions enveloping the gall and remaining after the gall drops off. Q. coccifera, ilex, suber: Neuroterus anthracinus AG

3c Spindle-shaped or rotund swelling with more or less bulging surface, on Q. coccifera, suber: Andricus quercusradicis SG and/ or Andricus testaceipes SG

3d Galls ± oblong-oval, about 2 mm long and 1–1.5 mm high, longitudinal axis in the leaf blade, usually next to a main vein and leaf margin emarginate towards the vein. Yellowish to brownish, with distant simple, whitish hairs, thin-walled. Containing a single larva. Q. coccifera: Andricus schroeckingeri SG

4a Gall on leaf blade => 6

4b Affecting only the edge of the leaf blade => 5

5a Hypertrophied discoloration of the more or less folded leaf margin. Q. ilex: Phylloxera coccinea and/ or P. quercus, Ph. ilicis

5b Margin of the leaf lobes broadly folded downwards. Outside of the gall slightly thickened, often marbled. Containing usually only a single yellowish-white larva per gall. Q. coccinea, but more frequent on Q. cerris and other deciduous oaks: Macrodiplosis pustularis

6a Gall distinct on only one of the leaf surfaces, or unequally protruding on one side => 14

6b Gall equally distinct on both leaf sides, well-marked protruding => 7

7a Closed gall wasp or gall midge galls => 10

7b Open galls caused by other gall causers => 8

8a Gall mite galls => 9

8b Small conical protrusion, 1 mm across, on leaf upperside. Containing, in the cavity below, a froth-covered nymph covered by scales. Q. ilex, suber: Trioza ilicina

9a Oval depressions, several mm across, on leaf underside, bulging on upperside, covered with rust-coloured erineum of very variable stellate hairs, usually with rays slightly swollen in the middle. Q. cerris, coccifera, ilex: Aceria ilicis s.l.

9b Erineum along swollen main veins on underside of leaf consisting of many short hairs which are terminally strongly dilated and club-like. Q. ilex: Aculops coutierei

10a Gall distinct on both leaf sides, weak, pustule-shaped protrusions => 12

10b Large ovoid, usually bright-coloured galls => 11

11a Galls globular, one-chambered, succulent, bright red, weakly pubescent. Q. coccifera, ilex, suber: Plagiotrochus australis SG

= Inquiline cynipids: Synergus ilicinus, S. plagiotrochi.

11b Galls ovoid, multi-chambered with many inner galls, including almost the whole leaf blade, leaving only its thorny teeth; red, scantily pubescent. Q. coccifera, ilex: Plagiotrochus quercusilicis SG

11c Gall ovoid, whitish and pubescent, disfiguring the leaf, its margin emarginate up to the gall, the emargination even reaching the midrib. Q. ilex: Neuroterus albipes SG

12a Pustules of regular outline => 13

12b Pustules of irregular outline, more or less elliptical or rotund, 3 mm across, equally protruding on both leaf sides, with small central verrucose patch and lateral exit hole. Q. coccifera: Neuroterus pustulifex ?G

13a Elliptical pustules, 1.5 x 1 mm long, brown above and pale green on the underside with lateral exit hole. Q. ilex: Plagiotrochus pustularis ?G

13b Similar, more rotund pustule, 2–2.5 mm in diameter, 1 mm thick, on underside mucronate; same colour as leaf but browning after adults have departed through a lateral exit hole. Q. coccifera, ilex, suber: Plagiotrochus coriaceus AG and/ or P. coriaceus var. barrensis ?G

13c Pustule brown, hardly protruding from upper- or underside, with a central navel on the underside, which, when drying out when mature, transforms into an operculum. Q. crenata, suber, also on Q. cerris: Janetia szepligetii

14a Gall distinct on only one of the leaf surfaces => 20

14b Gall unequally protruding on leaf surfaces => 15

15a Gall wasp galls => 19

15b Gall midge galls => 16

16a Acute conical protuberances => 18

16b Blunt conical, rotund-ovoid or pocket-shaped galls => 17

17a Pocket-shaped galls on the underside of leaf, with reticulate surface. Opens with slit on the upperside. Often several per leaf. Q. coccifera, suber:
Dryomyia cocciferae

17b Ovoid swelling on the underside of leaf, 3–3.5 x 2.5 mm; one-chambered. Opens with a slit on upperside, of which both edges are strictly closed over their length, except one of the extremities where they leave between them a circular opening. Many may occur per leaf, which may be distorted. Containing a single larva. Q. ilex, suber: Dryomyia lichtensteinii

17c Rotund to kidney-shaped gall on the underside, up to 6 mm wide and 2.5 mm high, provided with distant, yellow or grey, hairs. Often many galls per leaf blade. Containing a single larva. Q. ilex, trojana, suber, crenata: Dryomyia circinans

17d Gall flattened, hard, almost woody, up to 5 mm across, with a thick (2–3 mm) base, slightly convex in the centre with a small tubercle; on the leaf upperside with a round yellowish pustule, the middle conical, provided with some hairs. The under part, with a lid which drops off when mature, is felt-like pubescent. The larval chamber is situated at base in the thickened disc. Containing a single red larva. Q. ithaburensis, trojana: Janetia homocera

17e Upper part with broad base, blunt-conical; about 2 mm high, glabrous, yellow-brown. The only weakly protruding basal part on the underside is flat disc-like, with central channel and densely covered with distant, fine yellowish hairs. Between both parts is the elongated larval chamber. At maturity the basal part becomes lid-like detaches and drops off. Containing a single orange-red larva. Q. trojana, suber, crenata: Janetia cerris

= Inquiline gall wasp: Synergus variabilis.

17f Pustule galls. Q. ilex: Arnoldiola tympanifex

18a Small conical glabrous tube on the upperside, green or straw coloured; 0.5–0.6 mm high surrounded by a circular area 2–3 mm across; slight elevation on the underside. Q. coccifera, ilex: Contarinia luteola

= Inquiline gall midge: Dasineura ilicis

18b Similar gall, conical tube rarely straight 1.5 mm high and 1 mm in diameter. On the underside with a collar closing the gall exit, with yellowish hairs on the inside. Containing a pale yellow larva. Q. coccifera: Contarinia subulifex

18c Galls protruding on underside, 1.7–2.0 x 1.0–1.3 mm, apically fringed around opening. Causing a brownish spot on upperside. Containing a single yellow larva. Q. coccifera, ilex: Contarinia ilicis

18d Little conical leaf gall, ± 1 mm high, containing a single midge larva. Q. ilex: Contarinia minima

19a Gall cylindrical, usually predominantly on upperside only, glossy and covered with simple, straight, pinkish, rather long hairs. Q. coccifera, ilex, suber: Andricus crispator SG

19b Galls spherical, covered with long raised hairs which appear on the upperside like a disc-shaped projection and on the underside like a berry 3–4 mm across. Q. ilex, suber, frequent on deciduous oaks: Neuroterus tricolor AG

19c Galls vitreous berry-like, almost spherical; with thick, very succulent translucent wall. Q. coccifera, frequent on deciduous oaks: Neuroterus quercusbaccarum SG

20a Closed gall wasp galls => 21

20b Oval depressions, several mm across, on leaf underside, bulging on upperside, covered with rust-coloured erineum of very variable stellate hairs, usually with rays slightly swollen in the middle. Q. coccifera, ilex, suber: Aceria ilicis

20c Leaf blade spoon-like, curved towards the lower surface. Aphid yellow. Q. suber, also known from Q. robur, petraea: Tuberculatus annulatus

21a Gall flattened, lenticular, rotund, 3–5 mm across, white or ± red, flat above, with slightly elevated centre, margin below curved. Whole surface provided with long silky hairs. Containing a single larva. Q. coccifera, ilex, suber: Cerroneuroterus lanuginosus AG

21b Very small rotund gall, not exceeding pinhead-size, covered with small tubercles. Q. coccifera: Cerroneuroterus minutulus AG

21c Galls about 8–10 mm across, spherical, pale brown, dull, smooth. Q. coccifera, faginea, ilex, pyrenaica, also on deciduous oaks: Cynips quercus AG

21d Galls rotund-ovate, above the larval chamber is a second empty one. Usually with several galls on the side veins; 4–6 mm across, smooth or bumpy surface; narrowed at base, flattened at top and often with ± depression and centrally a navel-like protuberance. Wall hard. Q. canariensis, coccifera, ilex, pyrenaica, suber: Cynips disticha AG

21e Galls only 1.5 mm across, lenticular, the margin thickened and with concave surface, covered with short whitish instead of golden-brown (in Q. cerris) silk-like hairs. Q. suber, also on Q. robur, etc: Neuroterus numismalis AG

21f Elliptic, unilocular gall of ± 2 mm long, numerous on the underside of the leaf. Around each gall the leaf is sunken deeply. The wall is thin, smooth, shiny straw-coloured; at the tip is a group of white hairs that are curving back to the base of the gall. Q. coccifera x suber: Andricus luisieri ?G

Evergreen oaks, on male catkins

1a Whole catkin disfigured by protrusions which are covered with a reddish-brown erineum. Stamens elongated, sometimes irregularly bulging; 5–6 mm long, 2mm in diameter, covered with a thick felt-like layer of straight or twisted stellate hairs which radiate into rather thick, cylinder ending in a sharp point. Q. ilex: Eriophyes licopolii

1b Gall wasp galls, only disfiguring parts of the catkin => 2

2a Rachis swollen => 3

2b Galls on (parts of) flower => 4

3a Conspicuous spindle-shaped multi-chambered succulent swelling of rachis, up to 18 mm, 12 mm in diameter; red or green; weakly pubescent on which in a regular pattern of pits the white-yellowish, more or less disfigured flowers are attached. Each chamber containing a single larva Q. coccifera, ilex: Plagiotrochus quercusilicis SG

3b Stalked gall body spindle-shaped to conical, about 10–12 (16) mm long and 3 mm wide, thin-walled, hard, with large chamber. Q. ilex: Andricus solitarius AG

3c Rachis swollen and twisted into a series of ovoid one-chambered thin-walled, silvery pubescent galls, 1.6–1.8 x 0.7 mm. Each containing a single larva. Q. ilex, suber: Plagiotrochus amenti SG

= Inquiline gall wasps: Ceroptres cerri and Synergus gallaepomiformis

4a Galls originate from disfigured stamens, less than 4 mm in diameter => 8

4b Galls originate from flowers => 5

5a On Q. trojana => 7

5b On Q. coccifera, suber => 6

6a Galls moderately -sized, ovoid or pear-shaped, 6–8 x 3–4 mm, red-brown, slightly glossy when dry, sometimes slightly rugose, glabrous. A cylindrical cavity which is open to the outside containing a spherical inner gall. Each containing a single larva. Q. coccifera, suber: Andricus grossulariae AG

6b Outer wall tough. Galls about 10 mm long and 6–8 mm wide, ± glabrous, green, yellow or red. Single gall urn-shaped, middle part swollen, base narrowed, apex running into a deflected, undulate margin; often several together in a 20–40 mm long cluster. Upper half wide open, in the under half tissue several oval larval chambers each containing a single larva. Q. suber: Andricus lucidus SG

6c Galls clustered on rachis, which is not swollen or shortened. Each gall is provided on its base with remains of dried flower parts; galls cylindrical, 10 x 3–4 mm, the upper part (1–2 mm long) is obtuse or transversally compressed. Surface glabrous, yellowish partially reddened, more or less wrinkled at maturity. Larval chamber elliptical, 2 x 1.5 mm, thin-walled within a layer of 1 mm thick filamentous tissue; above the cavity is an elongate chamber which extends to the apex of the gall and is provided with a subapical round exit hole. Q. suber: Andricus cf. peyerimhoffi ?G

7a Single gall disc-shaped with tough outer wall. Usually compressed forming a ball 20 mm across, the single galls compressed forming a sort of tetrahedron; bright yellow or red-coloured. A large cavity in the broadened part, 2–4 larval chambers in the apex of the tetrahedron: Andricus cecconii SG

7b Catkin changed into a red disc, succulent, 5–13 mm x 4–6 mm, composed of a number of swellings each containing a thin-walled larval chamber; partially covered with grey hairs: Andricus zappellai ?G

8a On Q. suber => 9

8b On Q. ilex. Filament swollen and anthers stunted. Galls small, 1.0 x 0.5 mm, apex truncated, shrunken, sometimes twisted. AG undescribed: Plagiotrochus cardiguensis SG

9a Anther transformed into an ovoid gall, 1.5–2 mm long, which ends in an apical point, glabrous, one-chambered: Andricus quercuscalicis SG

9b Galls egg-shaped, 1.5–2.3 x 1.2–1.5 mm, provided with four longitudinal ridges which converge to the tip; they result from transformed stamens and are clustered in groups of 10–20 single galls. Each containing a single larva: Andricus burgundus SG

9c Galls in same tissues, 10–20 mm, some galls are irregular in shape and only 5–10 mm across: Synophrus hispanicus AG

9d Bud with flowers enlarged, half-opened, containing 5–10 small ovoid disfigured stamens; the galls are glabrous, shiny, bright red, about 2 mm high: Andricus hispanicus SG

Evergreen oaks, on acorns and acorn cups

1a Acorn embedded in an artichoke of scales => 4

1b Artichoke of scales absent. Gall woody, multi-chambered, brown, developed from the acorn membrane => 2

2a Acorn with ridged, sometimes even cracked surface => 3

2b Acorn curved, tip almost reaching the margin of the cup. Inside with a basal larval chamber. Containing a single larva. Q. suber: Plagiotrochus burnayi ?G

3a Margin of cup disfigured by gall mites, slightly thickened and pubescent. Q. ilex: Aceria ilicis

3b Cup disfigured by aphids. Q. suber and other evergreen oaks: Thelaxes suberi

3c Gall hard, multi-chambered, originates from the acorn scale. Each chamber containing a single larva. Q. ilex, suber: Callirhytis glandium AG

= Inquiline gall wasp: Synergus crassicornis

3d Galls arising externally at the base of the cup; helmet-shaped. Woody, brown-red, glossy, sticky; up to 25 mm high and 20 mm wide. Containing a single larva. Q. ilex: Andricus dentimitratus AG

3e Brownish, not sticky, gall on the atrophied acorn formed by two parts, the basal part a spherical cap, the upper part blunt conically, the basal ring of the cap being in contact with the truncated cone; the circumference of the latter is moreover decorated with small appendages. Q. ilex: Andricus quercustozae AG

= Galls of Andricus insanus strongly resemble those of A. quercustozae but they are permanently viscous (those of quercustozae only when young) and the spines are not arranged in a neat circle, but rather scattered in several circles.

3f Multiple one-chambered galls in acorns of all evergreen oaks: Callirhytis rufescens AG

3g Elliptic, about 3 mm long gall between the acorn and the locally ± disfigured cup. The gall is shiny, smooth, thin-walled. Q. lusitanicus: Andricus nobrei ?G

4a Gall developing at the expense of the atrophied acorn. The swollen cup is covered with elongated green and red scales. Q. suber: Pseudoneuroterus saliens SG

4b Gall terminally on a stalk which is covered by bud scales; spherical or ovoid, 7 mm across. It is green during immature stage and provided with stellate hairs. When mature, the periderm becomes grey and rugose and can be peeled off in polyhedral plates. The bud scales drop off and the stalk thickens to the same diameter as the gall, which then appears to be sessile. Normal buds may later develop on the stalk: Unidentified gall wasp

een gallengids

pub 19.x.2017

Een nieuwe veldgids voor plantengallen door Roelof Jan Koops

Continue reading “een gallengids”

Tabel voor de Euura-soortengroepen

pub 8.ix.2017

Tabel tot de soortengroepen binnen het grote geslacht Euura

Continue reading “Tabel voor de Euura-soortengroepen”

Arnold Grosscurt’s “Plantengallen”

pub 1.ix.2017

zojuist verschenen

Continue reading “Arnold Grosscurt’s “Plantengallen””

Oversteken van een dikke nerf

pub 16.viii.2017

Hoe steekt Lyonetia clerkella een dikke nerf over?

Continue reading “Oversteken van een dikke nerf”

knoppergal

pub 1.viii.2017

De ontwikkeling van de agame generatie van de knoppergal

Continue reading “knoppergal”

albifasciella special

pub 1.vi.2017

Overproductie van eieren bij Ectoedemia albifasciella

Continue reading “albifasciella special”

Cerodontha subgenera

pub 28.iii.2017

Tabel voor de subgenera van het geslacht Cerodontha (Agromyzidae)

Continue reading “Cerodontha subgenera”

Bucculatrix frangutella cocon

pub 24.xi.2014

De cocon van Bucculatrix

Continue reading “Bucculatrix frangutella cocon”

gras-Agromyza

pub 7.viii.2010

Tabel voor de gras-bewonende Agromyza-larven

Continue reading “gras-Agromyza”

pseudo-Bucculatrix mijn

pub 13.x.2007

Een ongewone doodsoorzaak van een Stigmella-larve: een “pseudo-Bucculatrix“-mijn

Continue reading “pseudo-Bucculatrix mijn”