Usia unicolor Loew, 1873

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 : 82-84

Usia unicolor Loew, 1873

( Figure 7 , Figure 17 , Plate XXIV)

Usia unicolor Loew, 1873: 201 .

Type material examined. LECTOTYPE here designated; Uzbekistan, Келесъ/ coll. H. Loew/ Typus / Zool. Mus. Berlin ♂ [ ZMHB] ; PARALECTOTYPES; Uzbekistan, Келесъ/ coll. H. Loew/ Typus / Zool. Mus. Berlin ♀ ; Ташкентъ [= Tashkent]/ coll. H. Loew/ Typus / Zool. Mus. Berlin ♂ ; Ташкентъ[= Tashkent]/ unicolor Lw. / 9693/ coll. H. Loew/ Type / Zool. Mus. Berlin ♀ [ ZMHB].

Originally described from an unspecified number of specimens of both sexes. Four syntypes were found in ZMHB, two males and two females. A male in the best condition was selected as lectotype.

Other material examined. Kazakhstan (south), area south –3, Kzul-Kumi ur. Kara-mulia, 11 May 1960, leg. P. Lev [♀] ( ZMUM) ; 20km SE of Cajan, Glinkovo , 530m, 6 May 1994, [♂ ♀] ( MHNG) . Kyrgyzstan, Kara-Arthsa Tal, 35km ESE Dzhambul , 1220m, 2 May 1994, leg. B. Merz [1♂ 2♀] ( MHNG) . Turkmenistan, Imam-baba, 2 April 1964 [1♂ 2♀] ( ZMUM) ; Imam-baba, Tugai, 31 March 1964, leg. Yu. Chernov [♀] ( ZMUM) , Kopet-Dag, Kara-Kala, 27 April 1960, leg. Zhelokhovtsev [♀] ( ZMUM) . Uzbekistan, Surkhand, Jar-kurgan, 3 April 1959 [♂♀] ( ZMUM) ; 4 April 1959, leg. Zhelokhovtsev [3♂ 1♀] ( ZMUM).

Etymology. from Latin uni + color, “one colour”.

Diagnosis. A small shining black species known only from Central Asia. Entirely black, including the mesonotum which is smooth and shining, with no more than shallow wrinkles, the punctures small but readily seen. Anterior slope of mesonotum with extensive grey dust between paramedian lines and post pronotal lobes. Occiput entirely dusted, almost obscuring dark ground colour. Frons diverging slightly, hairless on hind half away from ocellar area, anterolateral dust spots contiguous across the frons above the antennae bases, dusting lightly thinner centrally in some females. Longest scutellar hairs at least half scutellar mid-length, all vestiture rather fine and white. Pleurae entirely grey dusted. Wings clear the anal lobe narrow, almost linear in male, as wide as anal cell in female. Genitalia fairly large and conspicuous.

Redescription. Measurements. Body length. 2.5–4.5mm. Wing length. 2.8–4.6mm.

Male. Head. Black in ground colour, mouth-margin very narrow, linear, shining brown to black. Frons shining black centrally immediately in front of front ocelli, rather more matt and with reticulate surface sculpture adjacent to eye and across middle, densely grey dusted anteriorly, this dusting extending further back laterally. Frons almost parallel sided for hind half, widening slightly but noticeably anteriorly, lateral ocellus separated from eye margin by about the diameter of that ocellus. Occiput rather densely grey dusted, quite obscuring ground colour except on triangle behind ocellar tubercle which is a little less densely dusted. Hairing on head white, that on ocellar area conspicuously long, wider than width of frons. Hairs on upper occiput about half length of ocellar hairs, ventrally as long or even longer. Antennae black, third segment longer than the scape and pedicel together, third segment tapering to a blunt tip, all segments with short setae above, those just before the apical sulcus only a little longer than remainder, sensilla very small and inconspicuous. Proboscis black, hairless, about as long as head and thorax together; palps short, black, clavate with pale hairs, the longest shorter than the length of the palps. Thorax. Black with post alar callus very slightly browner; mesonotum and scutellum largely smooth and shining with only shallow wrinkles, most noticeably on scutellum. Grey dusting obscuring ground colour on anterior slope of mesonotum lateral to the paramedian lines, on post pronotal lobe, notopleuron, above wing and more thinly so on post alar callus. Despite the smooth surface of the mesonotum, the hair insertions are inconspicuous, being small and simple; hairing long, whitish, the longest hairs almost as long as the mid-length of the scutellum (base to apex), very evenly distributed but more sparse than in U. incognita Paramonov especially laterally. Bare paramedian lines noticeable, extending one third of the way back; acrostichal row narrow 2–3 serial. Pleurae with a covering of dense grey dust obscuring ground colour, pronotum and posterior half of anepisternum sparsely covered with rather long white hairs. Wing. Wing membrane faintly yellow tinged, the veins a little darker yellow-brown, base of stem of r and base of costa darker brown. Anal lobe exceptionally narrow, linear, barely half the width of the anal cell, hind margin straight, r-m at or beyond middle of discal cell. Haltere. Yellow, becoming brown at base of stem. Legs. Entirely shining black, the coxae grey dusted like the pleurae, with long pale hairs; femora with rather long, sparse, pale hairs, longest posteroventrally exceed depth of femora; tibia and tarsi with only a covering of minute setulae. Abdomen. Shining black, surface sculpture consisting of short transverse wrinkles or ridges and warts, much more textured than the smooth mesonotum. Disc of the tergites covered with very short (but longer than in U. incognita ), dense, whitish, backwardly directed hairs; laterally and on the down-curved margins the tergites the hairs are longer, approaching the length of those on mesonotum. Sternites also with similar long, pale whitish hairs. Genitalia. Quite large and conspicuous below the tip of the abdomen, shining black and covered with pale hairs similar to those on the sternites but more brownish, longest and densest on the middle of the lobes of the gonocoxite.

Female. As male except as follows: frons wider and broadening evenly anteriorly, oral margin wider, hairing on mesonotum and abdomen a little shorter and anal lobe broader, as wide as anal cell and with an evenly convex margin. Abdomen conical tapering to a rounded point, apical sternite wider than long, convex basomedially, apical emargination small and shallow, in dry specimens pale dust discernable apicomedially. Furca poorly sclerotised, membranous apically, arms strongly arched.

Discussion. This species is clearly closely related to U. incognita which has closely similar male genitalia. These two taxa show no obvious affinities with any other known species.

Distribution. Only known from Kazakhstan, Kyrgyzstan, Turkmenistan, and Uzbekistan. Specimens relatively numerous for such a poorly studied area, probably not uncommon.

Figures

FIGURE 7. ♂ U. unicolor head and mesonotum dorsal.

FIGURE 17. ♀ U. unicolor head and mesonotum anterodorsally.