Euura fallax (Serville, 1823)

EUURA CLITELLATA GROUP

Euura fallax - Grooved Grass Nematine

Nematus fallax Serville, 1823
Nematus melanocerus Hartig, 1840
Pachynematus fallax (Serville, 1823)
Nematus xanthocarpus Hartig, 1840
Nematus schmidtii Gimmerthal, 1844
Pachynematus declinatus (Förster, 1854)
Nematus erythropareus Zaddach, 1884
Pachynematus chambersi Benson, 1948
Pachynematus sulcatus Benson, 1948
Pachynematus virginalis Liston, 1980
Pachynematus angustatus Lindqvist, 1949
Euura angustata (Lindqvist, 1949)

North to northern Scotland. Recent DNA analyses have resulted in the former calcicola being included in this species, as well as chambersi and sulcatus, the latter two species recognised by Benson but based only on single specimens (Musgrove, 2024).

The description here is taken from Muche's description of Pachynematus xanthocarpus which is considered as a synonym of fallax. The former Pachynematus species require further study and any descriptions are currently tenuous.

The female is black with yellow-brown below and between the antennal bases, the orbits, the posterior margin of the pronotum, usually a spot on the mesepisternum, a double spot at the base of the scutellum, the tegulae, more or less the edges of the mesonotum. Sometimes the mesonotum or the mesopleura are translucent brown, the sternites narrowly edged with yellow and the tergites yellowish brown on the sides. The hypopygium is yellowish brown. Legs yellowish with the coxae, more or less trochanters, base of the femora, apices of the tibia and tarsi black.

The male is black with only the labrum and genital plate yellowish, rarely also the posterior orbits and the tegulae pale. On the legs only the knees, tibiae and tarsi yellowish.

Euura fallax larvae are not described but are associated with grasses.

Size: 6.0 - 8.5mm.

GB IUCN status: Least Concern
GB rarity status: None

Distribution: England, Scotland, Ireland

Flight period: April to June

Plant associations: Grasses