Plant Parasites of Europe

leafminers, galls and fungi

gallers on Euphorbia

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

Last modified 24.viii.2020