Dichotomous table for gallers on Lonicera

by Hans Roskam

1a On parts above ground => 2

1b Roots with nodular galls. Lonicera spp.: Meloidogyne div. spp.

2a On inflorescences or flowers => 19

2b On vegetative parts => 3

3a On shoot tips or leaves => 6

3b On axial parts of shoots => 4

4a On young shoots => 5

4b Conspicuous proliferations mainly on the nodes of older axial parts of shoot. “Bacterial cancer”. Lonicera spp.: Agrobacterium tumefaciens

5a Oblong oval, one-chambered gall, swelling on one or all sides, extending over 2–3 internodes below the stunted shoot tip. Pith containing a white larva. L. caerulea, nigra, xylosteum: Hoplocampoides xylostei

5b Shoot axis at some distance from shoot tip with weak, sometimes twisted, 20–30 mm long spindle-shaped swelling. Pith containing a reddish-yellow caterpillar. L. caerulea, xylosteum: Pterotopteryx dodecadactyla

6a Galls on terminal parts of shoot => 18

6b Localised or expanded malformations on single or several leaves => 7

7a Locally defined galls on leaf blade, petioles or leaf veins => 16

7b Malformations on leaf margins or on large parts of leaf blade => 8

8a Cartilaginous or ± fleshy roll of leaf margin caused by gall mites or -midges => 14

8b Loose fold or spoon-like deflection of leaf blade, often with associated curling roll of margin, caused by aphids => 9

9a With less conspicuous additional malformations connected downward folds or rolls of margin => 12

9b Leaves discoloured, folded or rolled upwards, distorted on the ± stunted shoot tips; extensive infestation followed by colonisation of many leaves, which are partially bent or rolled upwards => 10

10a Galls inhabited during May, June, soon decaying. Aphids migrating to Apiaceae => 11

10b Upwards curled leaves bearing aphids still in early summer and even later. L. caprifolium, etrusca, implexa, periclymenum, tatarica: Hyadaphis passerinii

11a Shoot tips, as well as several neighbouring, prematurely developed side shoots, transformed into a drooping, densely leafed, 15–25 (40) cm long bushy bundle with ± whitish axial parts. Leaf blades strongly reduced, bent upwards along midrib, irregular pale-green. L. x bella, caprifolium, involucrata, ligustrina subsp. yunnanensis, x purpusii, tatarica, xylosteum: Hyadaphis tataricae

11b Similar malformations, on many leaves of often severely disfigured and strongly deflected lammas shoots on L. nigra, bearing several aphids: Hyadaphis sp.

11c On L. xylosteum and also on many other climbing species: Hyadaphis foeniculi

11d In upwardly-rolled leaves of L. nigra: Hyadaphis bicincta

12a Aphids sometimes ± frosted, however lacking conspicuous white-woolly covering of wax => 13

12b Aphid strongly white-woolly. L. alpigena, tatarica, xylosteum: Prociphilus xylostei

13a On L. alpigena: Rhopalomyzus poae

13b Aphid rolling leaves towards undersides and causing yellow and red spots. L. nigra, tatarica, xylosteum and relatives: Rhopalomyzus lonicerae

14a Narrow, ± succulent, but soft, usually glabrous roll of leaf margin caused by gall midge larvae => 15

14b Narrow, compact, upwards partial roll of leaf blade usually associated with undulate curling, sometimes red-margined, cartilaginous; occasionally, if strongly infected, together with downward protrusions. Lonicera spp.: Aculus xylostei

14c Narrow tight roll, usually downwards, often reddish, clearly thickened and causing crinkling of the leaf margin, or a pleat parallel to the leaf margin, about 2‒3 mm long or affect most of both margins; roll often lines with hairs. L. periclymenum: cf. Aculus xylostei

15a More or less soft, succulent, pale-green upwards rolls, mainly on the leaf margins of one- or both sides on a developing shoot. Containing several white or yellow-red larvae. L. etrusca, implexa, nigra, periclymenum: Dasineura periclymeni

15b Roll only slightly thickened, containing several milk- to yellowish-white larvae. L. caprifolium, etrusca, implexa, nigra, periclymenum, xylosteum: Macrolabis lonicerae

= The larvae might also live as inquilines in galls of previous midge

16a Parenchyma- or groove galls caused by gall midge larvae, often many per leaf => 17

16b Rotund yellow sori of fungus, on main leaf veins, -stalks, also on young stems sometimes joined to slightly swollen, also distorted pads. Lonicera spp.: Puccinia festucae

16c On the young leaves develop chlorotic spots, that turn yellow, then brown, finally they dry out and are silvery. The veins remain green. On the underside a white bloom of basidia. L. tatarica, xylosteum: Insolibasidium deformans

17a The whitish larvae develop at first in inconspicuous pustule-shaped galls in leaf parenchyma, later on ± yellow, up to 3 (5) mm long. L. xylosteum: Dasineura xylostei

17b Spindle-shaped, slender and flat, 5–7 (9) mm long galls. Larvae in tissue of main veins. L. xylosteum: Unidentified gall midge

17c Leaf blade with many grooves, arched on upper side, 1 mm long surrounded by an about 4–7 mm broad lighter area, each containing a white, often succulent enveloped larva. L. caerulea, periclymenum, xylosteum: Dasineura excavans

18a Often only slightly stunted shoot tip with some completely or only basally stunted, thickened, ± discoloured erect leaves. Leaf blades completely rolled inwards, transformed into a pale-green cone or leaf blades of leaf pairs rolled over one another on only one side, spreading their free, usually normal halves. Containing several to many white larvae. L. xylosteum: Unidentified gall midge

18b Similar, more closed galls with strongly developed thickening of leaf. L. caerulea: Contarinia lonicerae

19a Gall development of single or several separate flowers => 20

19b Complete inflorescence variously stunted and disfigured by aphids. Bracts distorted. Flower reduced, ± greenish or disfigured; stamens reduced, not extending; the discoloured corolla and bracts are irregularly distorted or rolled upwards. L. caprifolium, etrusca, implexa, periclymenum, tatarica: Hyadaphis passerinii and/or Hyadaphis foeniculi

20a Malformations caused by gall midge larvae => 21

20b Flower buds unopened, facultatively slightly swollen, containing a yellow caterpillar with dark dorsal stripe. L. caprifolium, periclymenum, xylosteum: Alucita hexadactyla

21a Flower buds shortened, ± strongly swollen. Corolla inflated, ± leather-like and thickened. Stamens and ovaries ± distorted. Containing several yellow, jumping larvae. [S]. L. caerulea, nigra, xylosteum, tatarica and other cultivated species: Contarinia lonicerearum

21b Similar galls, containing orange, non-jumping larvae. L. xylosteum: Placochela nigripes

21c In flower galls of Lonicera spp. occur also the white, non-jumping larvae of Arnoldiola sambuci

mod 30.iii.2020