Usia aeneoides 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 : 68-70

Usia aeneoides Paramonov, 1950

(Plate XVIII)

Usia aeneoides Paramonov, 1950: 369 .

Usia aenea Rossi var.: Becker, 1906b: 214.

Type material examined. Type locality Spain. The lectotype, designated by Zaitzev & Kandybina (1983), is in ZIS and it had not proved possible to visit or to borrow the specimen or obtain photographs. However, Paramonov’s description is quite adequate to be certain that the non-type material examined in this study belongs to this taxon.

Other material examined. Spain, Andalucia, Cortija del Alcazar, 990–1200m, N36°55′15″ W4°5′18″, 9 June 2006, leg. D.J. Gibbs [10♂ 12♀] ( PCDG) ; El Pardo [Madrid], Arias Encobet/ 11June 1905 / M.N.C.N, Madrid [♂] ; El Pardo [Madrid], Arias Encobet/ 1906/ M.N.C.N, Madrid [♀] ; Torre del Vinagre, 0 6 July [19]88/ Sierra de Cazorla, Jaen España, Col. C.M. Herrera/ Usia aenea, Rossi, A. Sanchez-Terrón det./ M.N.C.N, Madrid [♀] ; 4 June 1963, Province Madrid, El Chorro, Leg. T.W. Tolman [♂] ( MNCN).

Etymology. from Latin aeneus meaning “bronzy” + - oides meaning resembling.

Diagnosis. A medium sized, compact, exceptionally short-haired species endemic to Iberia. An all black species, in natural light with a clear bluish hue, nearly all hairs on head, thorax and legs very short and black to dark brown, longer yellow hairs on abdomen laterally and gonocoxite. Occiput densely grey dusted, oral margin very narrow, frons relatively narrow, with longitudinal and diagonal grooves. Mesonotal cuticle with strong serrate punctures that give it a very rough appearance, few smooth shining areas away from paramedian vittae. Wings in most specimens with clear pattern of yellow base, brown mid-anterior patch and clear tip and trailing edge. Genitalia large and prominent, lateral horn-like projections of gonostylus usually readily seen and rule out all but U. similis Paramonov . Furca with distinct step between ‘arms’ and apical part.

Redescription. Measurements. Body length. 4.3–6.0mm. Wing length. 3.9–5.2mm.

Male. Head. Oral margin very narrow, linear, disappearing below, shining black to brownish, narrower than tip of palps. Frons black, shining but conspicuously grooved diagonally in hind half, more shallowly so between dust spots, rather matt due to microsulpture. Anterolateral grey dust spots occupying most of width of frons, black, subshining middle strip narrower than each duster area. Eyes separated at their narrowest by about one sixth to one seventh head width, a little more than width across lateral ocelli inclusive, almost parallel in hind half, abruptly widening then continuing almost parallel to insertion of proboscis. Lateral ocellus separated from the eye margin by the diameter of that ocellus or slightly more. Ocellar tubercle shining, undusted, minute black setulae less than diameter of a lateral ocellus, frons in front of anterior ocellus glabrous. Occiput densely grey dusted, the black ground colour obscured including on most of the triangular depressed area behind ocellar tubercle. A fairly even covering of short black hairs across the dusted area, shorter and more even above, significantly longer close to lower oral margin. Ommatidia uniform in size across the eyes. Antennae black, third segment, almost longer than twice length of scape and pedicel together, parallel sided, sensilla inconspicuous, translucent brownish. All antennal segments with minute brown setulae above. Palps small, black, slightly browner basally, clavate tip wider than oral margin, the dark apical setae about half as long as the length of the palps. Proboscis shorter than headthorax length, black, dorsally hairless. Thorax. Mesonotum shining black with faint bluish hue under natural light, grey dusting on post-pronotal lobe and adjacent parts of mesonotum, notopleuron near suture and above wing root. Disc densely punctate, the individual punctures raised and stellate, often coalescing to create a rough texture to cuticle. On disc any areas of smooth shining cuticle small and usually cross-striated. Paramedian vittae usually traceable by their different surface sculpture, faintly transversely striate and hardly punctured, extending from anterior slope of thorax almost to wing insertions. Mesonotal vestiture very short, black setulae only readily visible on notopleuron and above wings, even shorter ones on anterior slope, disc essentially hairless but in some tiny dark setulae present barely longer than diameter of a puncture. Acrostichal punctures between the bare paramedian vittae in about 3–4 irregular rows. Scutellar punctuation and hairing as adjacent parts of mesonotum, looks naked but tiny black setulae often present. Pleurae uniformly grey dusted largely obscuring ground colour, except for the anterior, dorsal and posterior margins of anepisternum and a small median patch on anepimeron which are shining black. Short black setulae like those on notopleuron on posterior third of the anepisternum. Wing. Membrane with distinct brown markings extending from costa to vein M and faintly to Cu, distally to end of subcostal cell and just beyond r-m, contrasting with yellow base proximal to the humeral crossvein. Veins all dark brown except proximal to humeral crossvein where they are paler, yellowish. Crossvein r-m a little before the middle of discal cell, conspicuously beyond dm-cu. Anal lobe relatively narrow, trailing edge straighter proximally, convex medially, a little over half the width of anal cell. Haltere. Yellow, base of stem slightly brownish. Legs. Coxae black with a coating of grey dust like that on the pleurae. Remainder of legs black, undusted, shining below the setulae. Coxae externally with rather sparse short, black hairs, femora ventrally with short brown hairs, shorter than depth of tibia, hardly different from dorsal hairs. Tibia rather densely covered with short, recumbent, yellow-brown setulae. Abdomen. All tergites shining black, often with faint bluish reflections, slight dusting on down-curved margins, only obvious on first tergite. Each tergite densely punctured, the punctures tuberculate, often joined to neighbours by transverse ridges, each puncture with a tiny brown setae, hardly longer than width of a puncture. Apical rim of each tergite narrowly impunctate, smooth and shining. Sternites grey dusted, faintly punctate, with relatively long, erect pale yellow hairs. Genitalia. Large and globular, occupying much of underside of abdomen. Epandrium flaskshaped with rather triangular apicolateral blunt extensions, longer than wide, mostly shining black, the cuticle with simple punctures, evenly coated with short pale yellow hairs. Gonocoxite approximately square, shining black, orange-yellow apically where gonostyli articulate. Apicolaterally the gonocoxite has a conspicuous blunt ‘thumb’- like process surmounted by a brush of golden hairs. Gonostyli ‘T’-shaped with an inner, basal lobe, apex of epiphallus with two divergent, paddle-shaped lobes that can often be seen in pinned specimens.

Female. As male except as follows: oral margin significantly broader, but still disappearing below. Frons noticeably wider, about one-sixth head width, lateral ocelli separated from eye margin by about twice their diameter, diverging more evenly from vertex. Diagonal grooves in front of anterior ocellus deeper and minute setulae on front of frons between grey dust spots more apparent. Abdomen tends to be more aeneous with coppery, gold and even red reflections (incandescent light). Genitalia. Tip of abdomen coming to a rounded point; apical tergites much less densely punctate. Apical sternite almost square, rather large and convex, apical notch very small, barely visible. Furca pigmented, the arms long and attached to the apical part at a distinct step, lacks any pigmented vaginal plate.

Discussion. This very distinctive species is clearly a sibling species of U. similis Paramonov which has closely similar male and female genitalia and much the same general appearance. Its relationship to other Usia species is less obvious, while it shares the same wing pattern with U. aenea (Rossi) , there is little else in common with this species.

Distribution. Endemic to Iberia and so far only found in Spain from Madrid south to Andalucia. Specimens in collections are rather few so seems to be a local species but can occur in large numbers when found.