Plant Parasites of Europe

leafminers, galls and fungi

gallers on genus Anthemis

Dichotomous table for gallers on Anthemis

(incl. Cota, Cotula)

by Hans Roskam

1a On above-ground part => 2

1b Roots with nodule-shaped slender humps, up to 4 mm, with beginnings of lateral roots. Cota tinctoria: Meloidogyne hapla

2a In capitula or fruits => 5

2b Plant partly or completely deformed => 3

3a Malformations by aphids or cercopids => 4

3b Plant bushy by inhibition of the internodes; mostly non-flowering; with pustule-shaped depressions over extensive areas, containing fruiting bodies. A. arvensis: Didymaria matricariae

3c Stem usually close to the ground with up to about 8 (12) mm long, broad spindle-shaped swelling, with a depressed break in the middle concealing a scale insect under a crooked shield. Cota tinctoria: Planchonia arabidis

4a Stems of young shoots locally stunted and curved; leaves closed, with their tips in different ways ± clump-like bent downwards. One froth-covered nymph. A. arvensis: Philaenus spumarius

4b Plant parts bunched together on the ± stunted shoot tips, downwards reflexed and curved; greenish aphids. A. arvensis: Brachycaudus helichrysi

5a Malformation of receptacle and of flower head => 6

5b Ovary or fruit swollen without or together with the lower flower parts. Also the bract may be involved in the gall formation. Containing a single yellow larva. A. arvensis, bornmuelleri, cotula, pseudocotula, rascheyana: Ozirhincus longicollis

5c Similar galls and biology. A. arvensis, bornmuellei, rascheyana, retusa; Cota tinctoria: 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.

6a Receptacle thickened or occupied by independent ± separate galls => 7

6b Capitula deformed in different ways. Marginal flowers partially excessively elongate, ± misshapen and bent; often containing many oospores. Mycelium extended over large parts of flower head, changing into dirty violet-grey layers of branched conidia locally at the surface. A. arvensis, cotula, ruthenica; Cota austriaca: Peronospora radii

7a Complete receptacle swollen and hardened => 8

7b Between the flowers up to 3 mm long, cylindrical-conical achene-like galls, which differ from achenes however by their smooth compact wall. The galls are firmly inserted in the receptacle; the conical top becomes detached at maturity. Containing a single larva. A. arvensis, cotula; Cota austriaca; Cotula triumfettii: Rhopalomyia syngenesiae

8a Malformations caused by maggots of tephritid flies => 10

8b Malformations caused by beetle larvae => 9

9a Receptacle enlarged 2–3 times, globular to ovate; wall thick and tough. Containing a single larva with head capsule. A. arvensis, cotula; Cota tinctoria: Omphalapion laevigatum

9b Recorded from similar galls on A. cotula: Omphalapion hookerorum

9c Slight malformation of capitula. Cota tinctoria: Omphalapion buddebergi

10a Receptacle swollen, malformed, hardened. Larva without distinct head capsule, with black mandibles. A. arvensis, cotula: Eurasimona stigma

10b Similar galls. A. arvensis, cotula: Trupanea stellata

Last modified 17.xi.2023