Usia bicolor Macquart, 1855

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 : 26-29

Usia bicolor Macquart, 1855

( Figure 1 , Plate III)

Usia bicolor Macquart, 1855: 103 (83).

Type material examined. HOLOTYPE: [ Egypt] Usia bicolor ♀ [sic.] Macq./ U. bicolor Ex coll. Bigot. [seems to have been incorrectly sexed by Macquart. ♂ in OUMNH].

Other material examined. Israel, Tel Mareshna, 2km WNW Hebron, 357m, 17 March 1986, (leg. A. Shmida)/ at Ornithogalum tenuifolium (White) Liliaceae ( OUMNH) ; Tel Aviv Country Club beach, 14 March 1995 ♂ ; Herzliyya, 11 March 1995 ♀ ; 14 March 1995 ♀ (leg. B. Merz) ; Shuneh Benjaminah, Coastal Plain, Palestine, 6 April 1953, O. Theodor [♂3♀] ; dunes, Hederah, Coastal Plain, Palestine, 5 April 1953, O. Theodor [2♀] ; Bet-Jibrin, Southern Palestine, 25 March 1954, O. Theodor [♂] ( TAU) Herzliyya, N32º11′ E34º48′, 15 March 2008, 2♂ 5♀ (leg. A. Nir) ( PCDG). Jordan, As Salt, 32 032N - 35 44E, Al Balqa Gov., 13 April [20]02 [♀] ; Aqraba, 32 43N - 35 47E, Irbid Gov., 25 March [20]02, on Linum pubescens Banks [♀] ( BMNH ex Greathead coll.). Lebanon, Alma a Shaib, 3 April 1978, D. Gerling [♀] ( TAU). Turkey, Içel, Gűzeloluk, N36°45′01.3″ E34°07′47.3″, 1335 m, 26 May 2005, 3♂ 12♀ ; Hatay, Yunushani, Yayla Dagi, 600 m, 8 May 2000, 3♂ 2♀ (leg. J. Dils & J. Faes) ; Hatay, Belenpas E-side, 25 June 1992 1♂ (leg. J.P. Borrie) ; Hatay, 20 km N of Botash, 26 April 2000, 1♀ (leg. J.A.W. Lucas) ( PCJD).

Etymology. from Latin bi+color for “two-coloured”, presumably referring to the bluish reflections on some specimens.

Diagnosis. Variable in size, from small to quite large, one of the most frequently met with Usia in the eastern Mediterranean. An all black species, often with a faint bluish sheen and short, erect whitish vestiture. Occiput densely grey dusted, male eyes separated by distance across lateral ocelli, a series of distinct hairs bordering eye margins in front of anterior ocellus. Mesonotal vestiture short and neat, very even in length, Tibia similarly clothed with short, even hairs. Wings hayline with a brownish infuscation basally. Genitalia typical of the group differing only subtly from close congeners; apices of gonocoxite convergent, tips closely approximated or touching; furca with tip membranous.

Redescription. Measurements. Body length. 2.5–9.0mm. Wing length. 2.5–6.5mm.

Male. Head. Oral margin narrow, becoming narrower rearwards and disappearing below, shining black to brownish. Frons black, shining, conspicuously grey-dusted anterolaterally often distinctly longitudinally striated medially in front of depressed area in front of anterior ocellus. Eyes separated at their narrowest by about one fifth to one sixth head width, about equal to width across lateral ocelli. Lateral ocellus separated from eye margin by about half to two thirds diameter of that ocellus. Ocellar tubercle shining, undusted, eye margins in front of anterior ocellus diverging relatively evenly to rear of oral opening. Translucent white hairs on ocellar tubercle averaging width of frons, a few decidedly longer than width across lateral ocelli, rear of frons in front of anterior ocellus with distinct uniserial rows of proclinate setulae close to eye margins, about as long as scape, anterior part of frons with scattering of short setulae across most of width in places. Occiput densely grey dusted, black ground colour obscured except on triangular area behind ocellar tubercle, which is shining black. A fairly dense covering of pale yellowish hairs across dusted area, shorter, more even above, significantly longer close to lower oral margin. Ommatidia uniform in size. Antennae black, third segment, a little less than twice length of scape and pedicel together, narrow swollen below basally, concave medio-ventrally, sensilla inconspicuous, translucent brownish. All antennal segments with very short yellowish hairs above, longest just before apical sulcus. Palps small, black, apically, clavate tip a little narrower than oral margin, pale brown apical setae about half as long as length of palps. Proboscis shorter than head-thorax length, black, dorsally hairless. Thorax. Mesonotum shining black, sometimes with bluish reflections, grey dusting on anterior slope of mesonotum laterally, post-pronotal lobe, notopleuron and above wing root. Disc densely puncto-rugose, hairs issuing from confluent welts producing rough-textured, but still shining cuticle. Paramedian vittae usually just discernable by their different surface sculpture, more transversely wrinkled, extending from anterior slope of thorax almost to wing insertions. Mesonotum fairly densely clothed with fine whitish vestiture, on disc and posteriorly short, neat, erect to slightly reclinate, tending to proclinate close to scutellum, even in length, no hairs longer than those on upper occiput. Laterally hairs are longer and erect or inclined inwards ( Figure 1 ). Acrostichal hairs between he bare paramedian vittae multiserial, entirely erect to slightly reclinate, widening posteriorly, dorsocentrals not distinguishable from the general vestiture. Scutellum shining as adjacent parts of mesonotum, hair length as on mesonotum or even shorter. Pleurae uniformly grey dusted largely obscuring ground colour, no areas of shining cuticle. Long white hairs, longer than any on mesonotum, on pronotum and upper and posterior half of anepisternum. Wing. Membrane brown tinged, this infuscation more intense in cells c, sc, base of r1, and all but tip of first basal cell in most individuals, squama very pale yellow, veins all brown, darkest at base of C and Rs. Crossvein r-m at or a little before the middle of discal cell, conspicuously beyond dm-cu. Anal lobe moderately well developed, with evenly curved trailing edge, about two-thirds width of anal cell. Haltere. Yellow, base of stem slightly brownish. Legs. Coxae black with coating of grey dust as on pleurae. Remainder of legs black, undusted, shining below setulae. Coxae externally and femora ventrally covered with moderately long, white hairs, on mid and hind-femora a little more than greatest depth of tibia, shorter on front femora. Femora dorsally and tibia rather densely covered with short, recumbent, white hairs. Abdomen. All tergites shining aeneous black, often with bluish reflections, dusted on down-curved margins of first to third or fifth tergites. Each tergite densely puncto-rugose, surface sculpture of transverse welts each furnished with a hair, very narrow, smooth, shining apical margin. Disc uniformly and densely covered with very short, pale brownish, recumbent hairs, longer, whiter, more erect laterally. Sternites grey dusted, faintly punctate, with fairly long, erect white to very pale yellow hairs. Genitalia. Relatively small and simple, globular. Epandrium flaskshaped with apicolateral blunt extensions but lacking any median ‘V’-notch, mostly shining black, cuticle punctate, evenly coated with pale yellow curved hairs. Gonocoxite about twice as broad as long, shining black basally, rufous brown apically, tips closely approximate or touching, haired as epandrium, gonostyli simple, curved with basal ‘thumb’.

Female. As male except as follows: oral margin decidedly broader, in lateral view visible to rear of oral opening. Frons a little wider, about one-fifth head width, lateral ocelli separated from eye margin by about their diameter or a little more. Dusting of frons more conspicuous and extensive, extending down between eye and oral margin. Mesonotal vestiture often slightly shorter, the paramedian vittae often obscure so acrostichal rows difficult to distinguish. Genitalia. Tip of abdomen coming to rounded point; apical sternite subrectangular, the basal part partially divided from main part, apical notch present but not deep, although often visible in undissected specimens. Main part of apical sternite with raised transverse ridge clothed with long whitish hairs. Furca arms very long, but tip poorly sclerotised, membranous so difficult to see, conspicuous, rectangular, dark-pigmented vaginal plate.

Discussion. This common eastern Mediterranean species is very close to U. crinipes Becker and possibly conspecific, but the two are allopatric or parapatric and separated attitudinally. Also close to U. lata Loew , which shares the dusted occiput and epandrium lacking apical V-notch.

Distribution. Egypt (where only known from the holotype collected by Bigot at Cairo (Macquart 1855) so perhaps rare but likely to be found in the Sinai), Iran, Israel (very common), Jordan, Lebanon, Turkey (coastal provinces from Mersin to Hatay). As far as can be ascertained from locality data, this is a lowland species, especially abundant on coastal dunes in Israel, but with occasional specimens up to 1335m in Turkey.

Figures

FIGURE 1. ♂ U. bicolor frons.