Neria femoralis
Czerny, 1930: Male: frons narrowed anteriorly, frontal stripe rusty yellow, black around ocelli, in front of ocelli with a pointed whitish dusted triangle, reaching middle of frons. Eye margins whitish dusted anteriorly, lateral eye ridges and occiput black, with white dusting. 2-3 moderately long orbital bristles. Face and cheeks white, antennae rusty yellow, arista black, short plumose, plumosity decreasing in length towards apex, always bare at apex. Proboscis rusty yellow, palps whitish yellow.
Thorax black, with thick grey dusting. Pilosity extremely short, whitish. Pleurae beneath whitish grey, sternopleuron with white hair band, above with 4 long hairs. Scutellum at edge with fine white hairs. “p” (?coxa) rusty yellow, shining, F1 and F2 apart from black apical rings with median dorsal blackish brown stripe, t2 and t3 very pale brown , tarsi strongly brownish.
Wings somewhat brownish, calpters and halteres white. (Czerny, 1930)
Abdomen shining black, short haired, robust. 2nd segment with a small black mark in middle of fore margin, and on left side with a dark mark covering 2 segments (? 2nd + 3rd). 4th sternite extraordinarily wide, strongly curved rusty yellow lamellae, with toothed hind margin
Identification of females:
Returning with Martin Drake to his original UK site in 2018 he took a single female. In his 2003 paper he had stated "None of the females collected unambiguously fitted the key characters used by RohaCek and Bartak (1990)" However the new specimen (which was photographed) clearly does not fit the description of N.cibaria (the other species in the couplet in the R&B key), the ovipositor sheath differs substantially, it is broad (from a dorsal view), tapering almost to a point and brown with paler brown patches. Most certainly not the black shiny cylinder with a kink typical of N.cibaria and not like the figure in R&B 1990.
Distribution
Europe: Countries (published), online at Fauna Europaea, Occurrences at GBIF
UK: Recording Scheme map of occurrences 2016 (verified.) Online (NBN Atlas) via Easy maps or Interactive Atlas
Czerny, 1930: Stirn nach vorn hin verschmälert, Stirnstreifen rostgelb, um die Ozellen herum schwarz, vor den Ozellen ein mit der Spitze bis zur Stirnmitte reichendes weißschimmerndes Drei- eck, Augenränder vorn weißschimmernd, Scheitelplatten und Hinterkopf schwarz, weiß best äubt, 2-3 mäßig lange 01'. Gesicht und Backen weiß, Fühler rostgelb, Borste schwarz, kurz ge fiedert, die Fiedern gegen die Spitze zu von abnehmender L änge, die Spitze selbst nackt, Rüsselrostgelb, Taster weißlichgelb. Thorax schwarz, dicht grau bestäubt, Behaarung äußerst kurz, weiß lich, Pleuren im unteren Teile weißgrau, Sternopleura mit einem weißen Haarschirme, die obersten 4 Haare lang. Schildchen am Rande mit feinen, weißen H ärchen. p rostgelb, glänzend, f2 und f3 außer dem schwarzen Apikalringe oben in der Mitte mit einem schwarzbraunen Streifen, t 2 und t 6 sehr leicht, T ars en stark gebräunt. Flügel etwas gebräunt, Schüppchen und Schwinger weiß. Abdomen glänzend sch warz, Behaarung kurz, weißlichgelb, 6. Tergit mit breitem, gelbem Rande, Hypopyg rostgelb, 1. Segment mit einem größeren, 2. Segment mit einem kleineren schwarzen Flecke in de r Mitte am Vorderrande, auf der linken Seite ein über beide Segmente gehender schwarzer Querfleck. Am 4. Sternit (Textfigg. 10 u. 11) außerordentlich breite, stark gewölbte, am Hinterrande gesägte rostgelbe Lamell en. - Meigen erhielt diese Art von vViedmann aus Holstein, ich fing 1 cf in Bad Hall. 5,5 mm.
Almost unknown. Previously this species was considered very rare (Czerny 1930; So6s 1980] but it occurs, often together with N. cibaria, in lowlands along rivers and large brooks. The seasonal occurrence of N. femoralis was studied in an aider forest in the Moravice valley (second week of May, rising to a peak in the first week of June and ending in late June). The species was found to be more vernal and more stenochronous than N. cibaria, with a striking prevalence of males in the material collected (3:1) (Jindřich Roháček, 1990)
Silted areas (spring-fed flushes & overgrown pools in the UK) The presence of Ranunculus sceleratus amongst the plant communities may be significant. Adjacent refugia comprising Salix shrubs (see image)