Usia transcaspica Paramonov 1950
Creators: name: Gibbs, David
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Bombyliidae
Usia
Usia transcaspica

description: Usia transcaspica Paramonov, 1950
(Plate X)
Usia transcaspica Paramonov, 1950: 351.
Type material examined. HOLOTYPE; Turkmenistan, Transcaspia mont, Kopet-dag Tshulli, 21–25 May 1913, A. Hohlbeck / 1104/ Usia transcaspica sp. nov. S. Paramonov det. ♀ / Holotypus / Zool. Mus. Berlin [♀ in ZMHB].
Other material examined. Turkey, Adiyaman, Nemrutdagi, 1500–2100m, 1 June 1985, ♂ (leg. H. v. Oorschot) (PCJD); Armenia, 7km N Armash, 2 July 1959, ♀ (leg. L. Zimina) (ZMUM); Iran, Ghazvin, 1463m, road to Abazar village, N36°17′ E50°10′, pan trap, 16–17 June 2009, Leg. Babak Gharali [♂♀] (PCDG).
Etymology. named for the type locality east of the Caspian Sea.
Diagnosis. Perhaps one of the most readily identified Usia species, superficially more reminiscent of some Parageron. A strikingly marked black and yellow species, Both sexes easily identified by the combination of shining black disc of mesonotum, densely grey dusted marginally, largely undusted, shining black tergites with broad yellow apical margins and legs yellow but for blackish apical tarsomeres. Similarly patterned species of Parageron always have densely dusted or at least matt second to terminal visible tergite and all sympatric species have densely grey dusted disc of mesonotum.
Redescription. Measurements. Body length. 3.7–6.0mm. Wing length. 3.3–5.2mm.
Male. Head. Oral margin narrow but quite prominent above oral margin, disappearing below in lateral view, shining brown. Frons blackish in ground colour, sometimes paler medially adjacent to eye margin, grey-dusted except for small rounded shining patch, on some extending forward of antennal bases. Eyes separated at their narrowest by between one sixth and one fifth head width, about equal to width across lateral ocelli inclusive. Lateral ocellus separated from the eye margin by about half to two thirds the diameter of that ocellus. Ocellar tubercle shining, thinly dusted, subshining, eye margins in front of anterior ocellus diverging slightly, then relatively abruptly before continuing parallel to insertion of proboscis, there diverging to rear of oral opening. Fine white hairs on ocellar tubercle short, barely longer than space between lateral ocelli, frons in front of anterior ocellus glabrous. Occiput black in ground, often browner below close to oral opening, densely grey dusted, except small triangular area behind ocellar tubercle which is thinly dusted. Upper part of occiput with fairly dense covering of fine white hairs with conspicuously procurved tips, the hairs thinning out and becoming shorter below, opposite to the usual condition in Usia. Ommatidia uniform in size across the eyes. Antennae black, sometimes yellower on scape and pedicel, third segment, a little less than twice length of scape and pedicel together, narrow swollen below basally, narrowing apically, sensilla white. All antennal segments with very short fine white setulae above. Palps relatively long, yellow, barely clavate tip a little wider than oral margin, short white hairs below, those on tip hardly longer than width of palp a widest point. Proboscis relatively long, approximately equal to headthorax length, black, dorsally hairless. Thorax. Mesonotum with a shining black patch on disc of variable extent, broadly grey dusted on anterior slope of mesonotum outside paramedian vittae, leaving a shining black stripe extending to the pronotum or almost so, post-pronotal lobe, notopleuron along thoracic suture, above wing root, prohumeral area and rear quarter to third of disc up to scutellum. Disc finely punctured, the hair insertions well separated by smooth shining cuticle. Paramedian vittae can be distinct, impunctate and finely transversely striated, reaching to wing insertions, or almost invisible. Mesonotum clothed with fairly long, fine silky white vestiture, erect to slightly reclinate, tending to proclinate close to scutellum, hairs as long as those on upper occiput. Laterally the hairs are longer and erect or inclined inwards. Acrostichal hairs between the bare paramedian vittae multiserial, entirely erect to slightly reclinate, widening slightly posteriorly, dorsocentrals not distinguishable from the general vestiture. Scutellum dusted as adjacent parts of mesonotum, hairing as mesonotum, cuticle smooth, unwrinkled. Pleurae uniformly grey dusted largely obscuring ground colour, except for a small area of shining cuticle on anepisternum anterodorsal in some individuals. Fine white hairs, like those on mesonotum, on pronotum and upper half of the anepisternum. Wing. Membrane clear, lacking any infuscation, veins all yellow, darkening slightly distally. Crossvein r-m at or a little before the middle of discal cell, conspicuously beyond dm-cu. Anal lobe well developed, with strongly curved trailing edge, wider than anal cell. Haltere. Yellow, base of stem slightly brownish. Legs. Coxae brown, becoming blacker basally, with a coating of grey dust like that on the pleurae. Remainder of legs yellow, undusted, shining below the setulae, except tip of basitarsus and apical tarsal segments which are dark brown to blackish. Coxae externally covered with moderately long, white hairs, especially apically. Femora, tibia and tarsi covered with short setulae, even those on femora shorter than width of tibia. Abdomen. All tergites shining black on disc with broad yellow apical margins that continue on to down-curved margin where it narrows slightly, tergite one thinly dusted laterally. Each tergite densely punctate, the punctures somewhat transverse forming a surface sculpture that gives the appearance of transverse striations. Disc uniformly and densely covered with fine, pale yellow, recumbent hairs, longer and more erect laterally. Sternites blackish brown with thin grey dusting, faintly punctuation almost invisible, with fairly long, recumbent pale yellow hairs. Genitalia. Relatively large and conspicuous, elongate. Epandrium yellow with apicolateral extensions bluntly pointed, the tips black, in dorsal view apical margin rectangularly emarginated, shining, the cuticle distinctly punctate evenly coated short pale yellow hairs. Gonocoxite about twice as broad as long, dusky basally, yellow in apical half, the tips curving towards each other but well separated, haired as epandrium, gonostyli slightly curved, truncate with basal ‘thumb’ and an external ‘step’.
Female. As male except as follows: oral margin decidedly broader, more convex but still disappearing below. Frons a little wider, about one-fifth head width, a little wider than distance across lateral ocelli. Mesonotal vestiture often slightly shorter. One female from Armenia with black coxae, trochanter and all but tip of femora. Genitalia. Tip of abdomen coming to a rounded point; apical sternite rather rectangular, yellow, the basal part partially divided from the main part, no apical notch present but short median projection. Main part of apical sternite with raised basal boss, sclerite clothed with very short white hairs. Furca typical of the group, with rounded tip sometimes with short spine apically, arms long, conspicuous rectangular, dark-pigmented vaginal plate.
Discussion. This very distinctive species is by far the most differentiated of the lata -group. Apart from the very obvious pattern of yellow, it has more extensive mesonotal dusting, longer occipital hairs above than below, smoother more finely punctured mesonotum and scutellum and broader anal lobe than in other species. In the latter two characters it approaches the condition seen in some Parageron with similar abdominal pattern. However, the male and female genitalia clearly place it in the lata -group and lack the diagnostic characters of Parageron so the similarities with Parageron are coincidental.
Only five specimens have been seen which exhibit considerable variation in size, extent of mesonotal dusting and leg colour in the females. When much more material becomes available it will be worth looking to see if there is more than one species involved. However, amongst the four dissected specimens there no clear evidence of more than a single species.
Distribution. Armenia, western Iran, eastern Turkey and Turkmenistan, poorly studied areas but does not appear to be very common.
description: Published as part of Gibbs, David, 2014, A world revision of the bee fly tribe Usiini (Diptera, Bombyliidae) Part 2: Usia sensu stricto, pp. 1-85 in Zootaxa 3799 (1) on pages 45-47, DOI: 10.11646/zootaxa.3799.1.1, http://zenodo.org/record/286090