Plant Parasites of Europe

leafminers, galls and fungi

gallers on Helianthemum

Dichotomous table for gallers on Helianthemum

by Hans Roskam

1a On inflorescences, flowers, capsules or on leaves => 4

1b On shoot tips or axial parts of shoot => 2

2a On shoot tips => 3

2b Shoot axis with ± expanded, sometimes bent, spindle-shaped to bulging swellings, in variable number, each containing the causer in a rimmed small groove. Helianthemum spp.: Planchonia arabidis

2c Swelling of 3 mm across. H. rosmarinifolium: Cistapion cyanescens

3a Tuft- or bud-like clustering of widened, thickened, often densely haired leaves. Containing several orange-yellow larvae. H. canum, nummularium & subsp. grandiflorum + obscurum: Dasineura helianthemi

3b Subglobose terminal gall, 4–5 mm across when young, composed of tightly imbricate, green or pale pink, leaves, shorter and a little wider than normal leaves. Mature gall up to 10 mm long, slender and consists of chestnut-brown, tough, curved scales. Gall one-chambered, rotund, containing a red larva. H. salicifolium: Unidentified gall midge

3c Cluster of whitish pubescent, short, thick leaves terminally on twig. H. croceum: Unidentified gall midge

3d Both terminal leaves of a shoot folded together, developing into a spindle-shaped gall, up to 6 mm long and 2 mm thick. H. canum: Unidentified gall midge

4a On inflorescences, flowers or capsules => 6

4b On leaves => 5

5a Expanded parts of leaves covered with long, 1-celled, browned hairs. H. nummularium: Unidentified gall mite

5b Leaves rolled inwards. Helianthemum spp.: Aphis helianthemi

6a Galls limited to flowers or capsules => 7

6b Complete inflorescence transformed into a dense mass of small, abnormally haired leaves, with ± excessive branching and leafiness. H. canum, nummularium & subsp. obscurum, oelandicum, stipulatum: Aceria rosalia

7a Malformations of flowers => 8

7b Minor swelling of ovary in flowers with stunted perianth. Containing a curved larva. H. nummularium & subsp. obscurum, ovatum: Phrissotrichum rugicolle

7c Minor malformations on capsules. H. nummularium & subsp. obscurum:
Helianthemapion aciculare

8a Flower buds thickened, unopened. H. nummularium: Unidentified gall midge

8b Flower buds slightly disfigured, but with strong abnormal pubescence. H. nummularium: Unidentified gall midge

Last modified 22.iv.2020