Homotropus melanogaster

Homotropus melanogaster (Holmgren 1872, Bassus)

Diagnosis. Fore wing length 3.8–4.7 mm. Antenna in females with 17 to 19 flagellomeres, apical flagellomeres with multiporous plate sensilla also present ventrally; in males with 19 to 20 flagellomeres and with narrow, long tyloids on flagellomeres 7 to 14–16. Face strongly coriaceous, punctures disappearing against the background sculpture. Clypeus weakly excised, with lobes rounded. Mesopleuron partly coriaceous on lower half, mainly smooth and shining on upper half, weakly punctate on lower half and along anterior margin. Mesoscutum coriaceous, especially on median part, weakly punctate. Hind coxa with hind surface smooth and shining between seta roots, coriaceous on basal half. Fore wing areolet closed, vein 3rs-m usually unpigmented. Propodeum with only pleural carina and apical parts of longitudinal carinae indicated but sometimes with some rugae on petiolar area which partly indicate the location of the petiolar carinae, coriaceous, smoother on petiolar area. Female metasoma strongly compressed posterior to third segment. First tergite without median dorsal carinae, at most with few longitudinal wrinkles, 1.0–1.1 times as long as wide in females, 1.0– 1.4 in males; second tergite basally with few weak longitudinal wrinkles, 0.5–0.9 times as long as wide, second tergite 0.9–1.0 times length of first tergite; spiracle of third tergite on dorsal part, above lateral fold.

Colouration of females. Antenna black. Head and mesosoma black, sometimes with yellow on central face patch which is sometimes confluent with yellow on clypeus, yellow on mouthparts, hind corner of pronotum, tegula, rarely subtegular ridge, sometimes upper part of mesepimeron; scutellum black. Legs orange, all coxae either black or orange, femora orange, hind tibia white with base, subbasal spot and apex dark, hind tarsus dark. Metasoma black.

Colouration of males. As in females but additionally with yellow over entire face, scape and pedicel ventrally, epicnemium, coxae apically.

Material examined. Holotype of Bassus melanogaster Holmgren: Denmark, Greenland. 1♂, at NRM.

New for Austria: Kaunerberg, 1500m, leg. I.&.E.Diller, 25.IX.1980. 1♀, at ZSM. New for Italy: Bolzano, Sarntal 1250m, leg. K.Zwakhals, 28.VI.1976. 1♀, at KZ. New for United Kingdom: Chippenham Fen., Cambs. Carr at reedbed edge, RMSNH 1986.021, 22.VIII.–5.IX.1985. 1♂, 1♀, at NMSZ.

Austria (1), Iceland (1), Italy (1), Sweden (15), Switzerland (11), United Kingdom (2).

Distribution. Holarctic.

Figures. Metasoma ♀ (Fig. 20 A), male terminal sclerites (Fig. 37 H).

Notes. While this species normally has entirely black coxae, I found several specimens in Sweden with entirely orange coxae. These were often sampled at the same location as specimens with black coxae. Except for colouration, no reliable characters could be found to distinguish these taxa, and I thus treat them as a single species.