Usia incognita Paramonov, 1950

Gibbs, David, 2014, A world revision of the bee fly tribe Usiini (Diptera, Bombyliidae) Part 2: Usia sensu stricto, Zootaxa 3799 (1), pp. 1-85 : 80-82

Usia incognita Paramonov, 1950

( Figure 18 , Plate XXIII)

Usia incognita Paramonov, 1950: 377 .

Type material examined. HOLOTYPE; Turkmenistan, J 68/ Usia incognita n. sp. ♂ Typus, Paramonov det/ Zool. Mus. Berlin [ ZMHB] .

Other material examined. [ Tajikistan, 939, Varzob, 25 May, 2♀, leg. A. Romanov (possibly this species) ZMUM].

Etymology. From Latin incognitus meaning “unknown” or “strange”.

Diagnosis (male only). A small shining black species known only from Central Asia. Entirely black, but mesonotum with fine surface sculpture producing a matt surface, effacing punctures but still sub-shining. Occiput entirely dusted, almost obscuring dark ground colour. Frons almost parallel, lacking conspicuous hairs away from the ocellar area. Longest scutellar hairs at least half scutellar mid-length, all vestiture rather fine and white. Pleurae almost entirely grey dusted. Wings clear the anal lobe convex, as broad as anal cell. Genitalia fairly large and conspicuous.

Redescription. Measurements. Body length. 3.8mm. Wing length. 3.2mm.

Male. Head. Black in ground colour, mouth-margin very narrow, linear, more brownish yellow, silvery grey dusted near antennae. Frons shining black, rather more matt and thinly dusted anteriorly, transversely wrinkled in front of ocellar tubercle; very parallel sided, barely widening anteriorly, lateral ocellus separated from eye margin by about the diameter of that ocellus. Occiput rather densely grey dusted, not quite obscuring ground colour. Hairing on head white, that on ocellar area conspicuously long, wider than width of frons. Hairs on occiput relatively dense, above about half length of ocellar hairs, ventrally as long. Antennae black, third segment longer than the scape and pedicel together, third segment rather contracted on apical half, all segments with very short setulae above with a group of longer setae just before the apical sulcus. Proboscis black, hairless, shorter than head and thorax together; palps short, black to brown, clavate with pale hairs, the longest shorter than the length of the palps. Thorax. Black with post alar callus somewhat brown; mesonotum and scutellum conspicuously shagreened, thus matt but still with a dull shine, a very narrow area of light dusting laterally above the wings. The rough texture of the mesonotum and scutellum largely effaces the hair insertions; hairing long, yellowish white, the longest hairs as long as the scutellar mid-length, very evenly distributed, the bare paramedian lines hardly indicated. Pleurae with a covering of dense grey dust obscuring ground colour, this dusting thinner on katepimeron which is more shining. Pronotum and posterior half of anepisternum covered with rather long white hairs. Wing. Wing membrane rather distinctly yellow tinged, the veins also yellow-brown, darker than the wing membrane, base of stem of vein r and base of costa darker brown. Anal lobe as broad as anal cell, with convex margin, r-m just before middle of discal cell. Haltere. Yellow, becoming brown at base of stem. Legs. Entirely dark brown, the coxae grey dusted; femora with rather long, pale hairs, tibia and tarsi with only a covering of minute setulae. Abdomen. Shining black, surface sculpture consisting of short transverse wrinkles or ridges. Disc of the tergites covered with very short, whitish hairs; laterally and on the down-curved margins the tergites are clothed with longer hairs, approaching the length of those on mesonotum. Sternites also with similar long, paler whitish hairs. Genitalia. Moderate size, conspicuous below the tip of the abdomen, shining black and covered with pale hairs similar to those on the sternites, longest on the gonocoxite.

[Female. No associated females seen. However, two specimens without associated males could be this species. They differ from the male in being generally shorter haired, frons broadening out anteriorly, proboscis longer (longer than head plus thorax); mesonotum smooth and shining, lacking the rough texture of the male holotype, and anal lobe a little narrower, less convex.]

Discussion. The two females described above and illustrated in Plate XXIII differ from the male holotype in ways that make it very uncertain that they are conspecific. Notably the narrower anal lobe than the male, the usual situation in Usia is for females to have a broader anal lobe than males of the same species. The best evidence that these are the females of U. incognita is the female genitalia which show considerable similarity with U. unicolor Loew. The male genitalia confirm that U. incognita ’s only known close congener is U. unicolor so, given that these female specimens are not U. unicolor , the only described species they can belong with is U. incognita .

However, it is equally probable that there is a third species in the incognita-unicolor group for which the males have yet to be discovered.

Distribution. Only certainly known from Turkmenistan.

Figures

FIGURE 18. ♀ [? U. incognita] head and mesonotum anterodorsally.