Usia pubera Strobl, 1906

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 : 73-76

Usia pubera Strobl, 1906

(Plate XX)

Usia pubera Becker, 1906b [May]: 204. Nomen nudum.

Usia florea var. pubera Lw. in litt.: Strobl, 1906 [June]: 287.

Usia atrata : of authors, misidentification.

Type material of U. florea var. pubera examined. LECTOTYPE here designated; Italy, [small red square]/ Usia pubera Lw. Calabria ♀ [corrected to ♂]/ Syntypus (leg. Erber) [ NMBA] ; PARALECTOTYPES; [small green square]/ Neapel [Naples] ♀/ Syntypus [ NMBA] ; Spain, Escorial, Puerto/ Colección, [leg.] Lauffer/ M.N.C.N., Madrid [♀ MNCN].

Other material examined. France, Alpes-Haute Provence, Sisteron, Gap, Peipin, N44º07′ E5º56′, 31 May 2002, 1♂ leg. D.A. & E.T. Levy ; Sault, Monte Ventoux, 1300–1400m, 27 June 1991, ♀ leg. L. Lanioreijer & W. van Steenis ( PCJD). Italy, Puglia, Castel del Monte, 300m, 24 May 1995, 4♂ ♀ ; Foresta Umbra, 400m, 24 May 1995, ♂ leg. J. Dils ( PCJD) ; Abruzzes, L’Aqulla, Monte Lucco, 700–990m, 7 June 1952, ♂2♀ ; 19 June 1852, ♀ ; San Giuliano, 700–990m, 2 June 1952, ♀ leg. F.G. Overlaet ; ex coll. B. Aldgren ( PCJD). Spain, Meigen, Usia florea , Spanien [♀] ( MNHN) ; Palencia, Aguilar de Campoo, 19 June 1980, 2♂ leg. P.J. Chandler( PCDG) ; Bnco., Moreno, S.Almijara-Má, 4♂ leg. A. Cobos; ex coll. B. Aldgren ( PCJD) ; Andalucia, Colado de las Sabinas, N32°6′38″ E3°25′14″, 2145m, 6 June 2006, 2♂ ♀ leg. D.J. Gibbs ( PCDG) ; Algeciras, S. Rogue, 1 May 1974, ♀ leg. K.M. Guichard ( BMNH) ; Palencia, 8km S of Cervuera de Pisuerga, 9 June 1986, ♂ leg. J.P. Duffels ( PCJD).

Etymology. from Latin puber meaning “downy” or “hairy”, referring to the relatively long, dense vestiture of this species.

Diagnosis. A usually large black species with a distinctly hairy look found in southwest Europe. All shining black, often appearing aeneous green, occiput densely dusted except behind vertex, hairs on ocellar tubercle longer than width of frons at narrowest point. Mesonotal vestiture long, all acrostichals reclinate, marginal scutellar hairs almost as long as mid-length of scutellum. Anepisternum entirely dusted. Ventral hairs on hind femora longer than femora is deep. Wing tinged yellow basally, otherwise clear, veins yellow to pale brown. Genitalia rather small gonocoxite particularly short and often sunk into apical tergites; furca with tip pigmented, spermathecal reservoirs uniquely subspherical.

Redescription. Measurements. Body length. 7–10mm. Wing length. 6.0– 8.5mm.

Male. Head. Mouth-margin narrow, becoming narrower below but still visible to rear of oral opening, shining black. Frons shining black, partly matt due to fine surface sculpture and small punctures, narrowest a little in front of anterior ocellus, approximately one fifth head width, distinctly wider than width across lateral ocelli, lateral ocellus separated from eye margin by one and a half to two times the diameter of that ocellus. Frons grey dusted laterally on anterior half, the dust spots separated by an undusted area rather more than one third of the frons width at this point. Vestiture on ocellar area clearly longer than width of frons at this point, pale yellow, these hairs contiguous with much smaller and strongly proclinate ones laterally forward of anterior ocellus, fine white hairs across frons anteriorly, most conspicuous on undusted area. Occiput entirely grey dusted such that ground colour obscured, pale yellow hairs covering occiput shorter than those on mesonotum above, similar in length below. Ommatidia uniform in size across the eyes. Antennae black, third segment distinctly longer than scape and pedicel together, relatively narrow apically, swollen below basally, all segments with relatively long setae above especially on scape, pedicel and just before apical sulcus. Sensilla small, brown, occasionally whitish, usually inconspicuous. Proboscis black, hairless, about as long as mesonotum; palps short but strongly clavate, blackish with pale base and hairs, the longest about as long as the palps. Thorax. Mesonotum and scutellum shining black dusted on dorsum of post pronotal lobe and adjacent parts of anterior slope, notopleuron narrowly and above the wing bases. Cuticle smooth and shiny, hair insertions small and simple, on disc separated by their diameter, often rather more. Bare paramedian lines extending back to about the wing roots, each a little narrower than the midline which has 5–6 irregular lines of hairs, widening out slightly behind. Hind part of mesonotum with a more wrinkled or puckered cuticle, punctures hard to see, scutellum usually with shallow transverse grooves. Pleurae black with a covering of grey dust sufficient to obscure the ground colour except on a very narrow anterior strip of the anepisternum which is shining black. Mesonotum and scutellum covered with long pale yellow to almost golden hair, that on the disc of the mesonotum anteriorly is as long or longer than width of frons, the majority of hairs overlapping their neighbours by most of the length of a hair. In many individuals the hind part of the mesonotum adjacent to the scutellum with much shorter hairs. Posterior half of anepisternum and pronotum covered with equally long pale yellow. Sometimes a few fine pale hairs on the middle of the katepisternum. Wing. Wing membrane distinctly yellow-tinged anteriorly and basally, clear posteriorly and apically, the veins yellow, becoming pale brown distally, extreme base of costa blackish. Anal lobe well developed with smoothly curved posterior margin, as broad or broader than anal cell, r-m close to middle of discal cell. Haltere. Yellow, becoming slightly brown at base of stem. Legs. Entirely black, the coxae grey dusted with long pale yellow hairs on outer surface; femora shining, undusted with the longest pale yellow ventral hairs decidedly longer than the greatest depth of a femur, tibia and tarsi with covering of minute yellow to brown setulae, the tibia also with longer erect pale yellow hairs on basal half. Abdomen. Black, often with faint bronzy or greenish reflections, thinly dusted on lateral margin of first few tergites. All tergites dulled by closely packed punctures that are joined by transverse furrows or ridges forming the appearance of transverse striations, the disc of the tergites covered with yellow recumbent hairs significantly shorter than those on mesonotum. Laterally and on the down curved margins the tergites are rather densely clothed with long, erect yellowish hairs. Sternites grey dusted, also with similar long, pale yellowish hairs along their posterior halves. Genitalia. Rather small and contracted into tip of abdomen, shining black the gonocoxite covered in long, golden hairs similar to those on the lateral margins of the tergites, hairs on epandrium shorter, especially on disc. Apicolateral lobes of the epandrium with straight dorsal margin joining curved ventral margin at a right angle. The gonostyli are flattened and parallel sided with a small basal spur often visible without dissection (not visible in illustrations due to angle of view).

Female. As male except as follows: wider frons and significantly wider oral margin. Genitalia. Tip of abdomen coming to a rounded point, apical sternite longer than wide, trapezoidal, apicomedially with a pair of blunt processes separated by a space about as wide as one process. Furca with tip pigmented, tip narrowly rounded, spermathecae subspherical, pyriform, unique in the genus.

Discussion. This species has been misinterpreted by all workers from Becker (1906b) onwards (see discussion under U. atrata Fabricius ) all of whom referred it to U. atrata . Examination of the types of U. atrata showed it to be a quite different species, which seems to be confined to North Africa and has hitherto been known as U. claripennis Macquart. The only valid name that proved to be referable to this species is U. pubera Strobl ( Chvála 2008) .

The affinities of this species are difficult to assess but it is closest in appearance to the U. florea group, especially U. atrata with which it was so long confused. The surface sculpturing, vestiture, including possession of a few hairs on the katepisternum, and shape of anal lobe are all highly suggestive of affinity with the U. florea group. Particularly significant is the small spur at the base of the gonostyli ventrally which, although smaller and straighter, is very reminiscent of the curved spur at the base of the gonostyli of U. atrata and U. cornigera Gibbs. However , U. pubera differs from the U. florea group in having an entirely densely grey-dusted occiput and, especially, uniquely shaped spermathecal reservoirs. Female genitalia in the Usiinae so often prove to be more informative than male genitalia or external features regarding inter-specific relationships that this latter feature suggests that U. pubera is best left out of the U. florea group.

Distribution. A fairly frequently encountered species of southern France, Italy and Spain (reported from Portugal under the name U. atrata and these will almost certainly prove to be correct).