Exoprosopa gracilis Greathead, 2006

Greathead, David J., 2006, New records of Namibian Bombyliidae (Diptera), with notes on some genera and descriptions of new species, Zootaxa 1149 (1), pp. 1-88 : 14-15

Exoprosopa gracilis Greathead sp. nov.

A slender black species with mostly gold scales and a white apex to the abdomen of males. The dark brown wing infuscation is similar in both sexes, Litorhina ­like similar to that of E. pterosticha Hesse but this species has a broad abdomen with bands of white scales.

Description. Holotype ♂. Size: length 9 mm; wing, 10 mm. Body: black, slender, abdomen no wider than thorax and almost parallel sided. Head: face conical marked off from frons by a groove at level of antennae. Ocellar triangle set forward of vertex by a distance equal to 1½ its length. Frons with shallow central depression. Hair black, scales glistening golden and with a fringe of short golden hairs at margin of central cavity. Eye facets small, scarcely enlarged above, indentation shallow but bisecting line long. Antennae with scape 1½ length of pedicel; first flagellomere as long as scape, conical, tapered from underside; second flagellomere as long as scape and pedicel together, narrow, rod­like terminating in a minute style. Proboscis longer than oral cavity, projecting by half length of labellae when fully retracted. Palpi elongate, black with black hairs. Thorax: hair and scales gold, also a patch of black hairs on propleura above front coxae and scattered black hairs among the gold hairs on mesopleura, no distinct patches of scales on sternopleura. Bristles black with a pair of very long ones on each post alar callus also a few fine black hairs on posterior half of mesonotum and scutellum. Legs: black with black bristles and hair, glossy black scales and also some golden ones on undersides of femora. Coxae with black hair and gold scales. Front legs slender not markedly reduced. Mid femora with one postero­ventral bristle, hind femora with four antero­ventral bristles. Claws slender, almost straight. Wing: (Fig., 7) basal hook black, comb small with fine black hairs and golden scales. Membrane milky, iridescent in clear areas, infuscation dark brown with white praediscoidal spot and paler areas in middles of cell bm and at base of cell r1. Infuscation Litorhina ­like, occupying fore margin to end R 1 more or less straight to near end of M 1, extending into fore margin of cell m2, middle 1/2 cell dm clear then extending across wing to near end of anal cell and occupying most of axillary lobe except the outer margin. Alula completely infuscated and with a whitish fringe. Vein R 2+3 originates before the r­m cross­vein by a distance equal to its length; interradial vein sinuous, recurrent; cell r5 only slightly narrowed before wing margin, r­m cross­vein at 1/ 3 length of cell dm, cross­vein m­m short and oblique to hind margin of wing so that dm is narrow but truncated. Squama brown with a yellow fringe. Haltere dark brown, paler at apex. Abdomen: pale yellow hair at sides of first tergum and gold scales in middle; sides of remaining terga and apex of seventh with black hairs; terga 2–6 with black scales at their bases and posterior 2/3 with gold scales; seventh tergum with dense silver scales. Sterna with sparse red­gold hairs and gold scales. Genitalia of holotype not dissected but see below.

Males show variation in the extent of the wing infuscation, the band across the middle of the wing may reach the hind border at the end of M 1 and less than half cell dm may be clear. Genitalia (Fig., 5) with bifid gonostyli; aedeagus very short and inconspicuous; epiphallus expanded bladder­like at apex, lateral apodemes large and heavily sclerotised; ejaculatory apodeme large, rounded and projecting forward of gonocoxae.

Females. Show very little sexual dimorphism. Only the gold scales on the abdominal terga tend to be paler yellowish­white towards the sides and the seventh tergum has gold scales at the mid line and yellowish white at the sides. The wing infuscation tends to be slightly more extensive so that the band in the middle of the wing is broader and the clear area in cell dm is reduced to a rounded spot in the middle of the cell and the basal infuscation reaches the wing margin at the end of vein Cu1A.

Material examined. Holotype ♂. Namibia: Rundu District, Mile 46., 18°18’39”S 19°15’29”, 25–27.iii.2003, A.H. Kirk­Spriggs, Malaise trap. Paratypes 3♂♂, 3♂♂, data as holotype (all in NMNW)..

Two additional specimens, damaged by Dermestes , also belong to this species but are not included as paratypes because they are damaged.

Material examined. NAMIBIA : 2♀♀, Gobabis District , Somerkroms 521, 22°01’59”S 19°57’22”E, 6–8.ii.2001, Kirk­Spriggs, Marais & Wheeler, Malaise trap sample ( NMNW) .