Plant Parasites of Europe

leafminers, galls and fungi

gallers on Leontodon

Dichotomous table for gallers on Leontodon

incl. Scorzoneroides, Thrincia

by Hans Roskam

1a On above-ground parts => 2

1b Nodule-shaped swellings of roots. L. alpinus, hispidus incl. subsp. hastilis: Meloidogyne hapla

2a On capitula => 16

2b On vegetative parts => 3

3a On leaves => 6

3b On stems => 4

3c All parts of shoot with white crusty blisters, very variable in size; shoot often distorted; L. hispidus, saxatilis: Pustula obtusata

4a More or less spindle-shaped and massive swellings, occasionally coalescing => 5

4b Shoots usually with expanded, spongy, swollen, ± bent or twisted pale green, massive galls of various size and position. On various occasions, basal parts of the capitula may be incorporated in the gall formation. Also on other organs. L. hispidus incl. subsp. hastilis, incanus; Scorzoneroides autumnalis, pyrenaica: Ditylenchus dipsaci

5a Shoot with weak, one-sided, one-chambered swelling. L. taraxacoides subsp. taraxacoides: Unidentified leafminer

5b Spindle-shaped or lenticular, enclosed by a ridge, depressions on ± swollen leaflets. L. hispidus; Scorzoneroides autumnalis: Planchonia arabidis

6a Galls exclusively on the main- or lateral veins, sometimes secondarily extending into the leaf blade => 13

6b Gall formation on the leaf blade or leaf margin independent of the venation => 7

7a Malformation without extensive involvement of the leaf margin => 9

7b Leaf margin rolled => 8

8a Leaf margins rolled upwards to different degrees, glabrous or ± abnormally pubescent, curled and rugose; also with localised swellings. Scorzoneroides autumnalis: Aceria anthocoptes

8b Leaf blades usually with discoloured marginal roll, as well as several groove-like protrusions each with a flat, white-margined froth-covered nymph. L. alpinus, hispidus incl. subsp. hastilis: Trioza dispar

8c Malformations on the underside of variously curved, sometimes ± twisted leaves. L. alpinus, hispidus incl. subsp. hastilis; Scorzoneroides autumnalis: Craspedolepta flavipennis

9a Galls without conspicuous additional pubescence => 10

9b Leaf blade on the upper surface or on the margin with abnormal formation of reddened hairs or protrusions. Sometimes weak upward marginal roll. L. hirtus: Unidentified gall mite

10a Galls compact, lacking cavities, caused by internally fruiting fungi => 11

10b Rounded pustule on upperside of leaf, about 4 mm across, purple-edged; usually several present; each containing an orange larva which can be seen through the transparent epidermis. L. crispus, hispidus incl. subsp. hastilis; Scorzoneroides autumnalis: Cystiphora leontodontis

11a Galls on the leaf blade flat wart-like, about 1.5–4 mm long; alongside sometimes spindle-shaped bulges on the midribs. Spores developing terminally on an intercellular mycelium, many, predominantly outside the vascular bundle => 12

11b Isolated galls less than 1 mm long, curved wart-shaped, yellowish translucent, consisting of a central fungus cell inside a nutritive host cell surrounded by a number of likewise strongly enlarged auxiliary cells; often coalescing to a larger, conspicuously reddish-yellow crust. On the rosette leaves, also solitary or in ± ridge-like bulges on the stem base. L. alpinus, hispidus incl. subsp. hastilis; Scorzoneroides autumnalis: Synchytrium aureum

= A similar fungus, Synchytrium saxifragae induces galls which are smaller and inconspicuous.

12a Flat, rotund, initially whitish hyaline, later on almost dark brown bulges on the underside of leaf blades, reddish in heavy infestations; alongside occasionally spindle-shaped swellings on the underside of main veins. Spores dark brown, ± rotund-oval, developing terminally on the leaf blade outside the vascular bundle. L. hispidus incl. subsp. hastilis; Scorzoneroides autumnalis: Protomycopsis leontodontis

12b Leaf underside with rotund swellings, 1.5–3.0 mm across, rarely elongated, flat, partially black-brown; alongside variously spindle-shaped bulges, up to 5 mm long on the underside of the midrib. Galls and surroundings sometimes bright red coloured. Spores dark brown. Scorzoneroides montana, pseudotaraxaci: Protomycopsis arnoldii

13a Gall causers not recognizable from the outside => 15

13b Malformations bearing brown sori => 14

14a Sori in irregular configurations predominantly on often strongly deformed petioles or stems as well as on yellowish to violet discoloured patches up to 8 mm wide, in crust-shaped groups on the leaf blades, displaying on the upperside honey-yellow spermogonia and on both sides red- to chestnut brown uredinia. Scorzoneroides helvetica, pyrenaica: Puccinia mayorii-eugenei

14b Small, initially yellow, later reddish coloured oblong bulges, usually on the underside on the main veins of the rosette leaves. Leontodon spp.: Puccinia hieracii var. hieracii

15a Affected venation swollen; leaf blade at site of infection usually yellowish discoloured and conspicuously pervaded by irregular thickness, intensively reddened, galled veins. Leaf blade slightly undulate deformed, at the margin sometimes ± downward curved. Stronger swellings of the midrib rare. Spores develop close to the vascular bundle. Leontodon hispidus incl. subsp. hastilis: Protomyces kriegerianus

15b Elongated spindle-shaped, also converging, pale green, spongy swellings of petiole as well as on midrib and main veins, locally similarly extending into the ± curved leaf blades. L. alpinus, hispidus incl. subsp. hastilis, incanus, Scorzoneroides autumnalis, pyrenaica: Ditylenchus dipsaci

16a Capitula swollen and variously disfigured => 18

16b Malformations associated with greening of florets => 17

17a apitula deformed to a pale grey, woolly, rotund structure. Florets greened and abnormally haired. Scorzoneroides autumnalis: Cause unknown – ? gall mite

17b Flower parts greened to a varied extent; capitula disfigured, sometimes bearing smaller disfigured capitula. Scorzoneroides autumnalis: Unidentified gall mite

18a The inducers are in the receptacles of disfigured capitula => 19

18b Capitula swollen, remaining closed. Several white larvae on the receptacle between the ± stunted florets. L. hispidus; Scorzoneroides autumnalis: ? Macrolabis sp.

19a Receptacle of swollen and variously distorted capitula containing 1–3 white larvae or brown puparia. L. hispidus, saxatilis; Scorzoneroides autumnalis, helvetica: Tephritis leontodontis

19b In capitula of L. alpinus, hispidus incl. subsp. hastilis: Campiglossa misella

19c Capitula often together with neighbouring stalks often spongy, swollen and curved. Inside the compact galls are many eelworms: Ditylenchus dipsaci

Last modified 30.iii.2020