Usia vestita Macquart, 1846

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 : 61-64

Usia vestita Macquart, 1846

(Plate XVI)

Usia vestita Macquart, 1846: 351 (223).

Usia anus Becker, 1906b: 207 , syn. nov.

Type material of U. vestita examined. LECTOTYPE here designated; Algeria, Oran / Museum Paris, Algérie, coll. H. Lucas 78-49/ TYPE [red label]/ 1215 [on reverse of round blue label]/ Usia vestita Macqt. sp. nov. [♂ in very good condition, right third antennal segment missing] ; PARALECTOTYPES; Oran / Museum Paris, Algérie, coll. H. Lucas 78-49/ Oran [reverse of round blue label]/ COTYPE/ U. vestita H. Lucas det. [♂ in very good condition, slightly mouldy]; Oran / Museum Paris, Algérie, coll. H. Lucas 78-49/ Oran, [illegible?date] [reverse of round blue label ]/ COMPARE AU TYPE / Usia aenea, Macqt. / vestita Macq. Det. Becker [♀ in reasonable condition, slightly mouldy and wing-tips broken][all in Macquart coll. MNHN].

Originally described from an unspecified number of specimens of both sexes. Three, two males and one female, were found in the Macquart collection in MNHN. The male in best condition was selected as lectotype.

Other material examined. Algeria, Alger [ Algiers], U. vestita Ex coll. Bigot [2♂ 2♀ in OUMNH. These four specimens are listed as syntypes in Greathead & Evenhuis 1999 but this is most unlikely to be the case (A.C. Pont pers. comm.; see discussion below)].

Type material of U. anus examined. HOLOTYPE; Algeria, Alger [ Algiers], U. vestita Ex coll. Bigot, Holotype of anus Becker [1♂ in OUMNH].

Etymology. vestitus from Latin vestiti meaning “clothed” referring to its covering of long hairs; anus from Latin meaning “rectum“fundament, buttocks or ring” presumably referring to the very large-sized genitalia relative to the size of the abdomen.

Diagnosis. A usually large black species with very long-haired reddish yellow vestiture only known from northern Algeria. All shining black, occiput shining and undusted above, thinly dusted below, hairs on ocellar tubercle longer than width of frons at narrowest point. Mesonotal, scutellar and abdominal vestiture very long, giving the insect a very furry appearance (diminutive specimens with much reduced vestiture do occur). Ventral hairs on hind femora much longer than femora is deep. Genitalia exceptionally large, equal to remainder of abdomen; furca with tip pigmented, coming to elongated blunt point.

Redescription. Measurements; Body length. 8–10mm. Wing length. 7–8mm.

Male. Head. Mouth-margin about as broad as the tip of the palps, relatively linear, shining black. Frons shining black except for grey dusting laterally on anterior half of frons, separated by an undusted area about one third of the frons width at this point. Frons narrowest level with anterior ocellus, lateral ocellus separated from eye margin by about the diameter of that ocellus. Occiput shining black above, thinly dusted below. Vestiture long, on ocellar area about as long as frons is wide at this point, pale golden yellow fading to white on lower part of head. Antennae black, third segment longer than the scape and pedicel together, all segments with pale hairs above, longest on scape. Proboscis black, hairless, about as long as head and thorax together; palps short, black, slightly clavate with pale hairs, the longest as long as the palps. Thorax. Mesonotum and scutellum shining black except for light dusting laterally and on post pronotal lobe. Smooth except for hair insertions, front third of mesonotum with bare paramedian lines as broad as acrostichal rows which has 3–4 lines of hairs. Hind part of mesonotum slightly wrinkled, scutellum strongly, transversely wrinkled. Pleurae black with a thin covering of grey dust not entirely obscuring the shine. Mesonotum, scutellum and posterior half of anepisternum covered with long, somewhat uneven hair (i.e. some hairs longer and standing proud of the general vestiture), hairs on the margin of the scutellum the longest. Hair pale golden yellow, more white on the anepisternum. Paler and sparser hairs on the pronotum and dorsal part of katepisternum. Wing. Wing membrane clear, faintly yellow tinged, the veins brown, becoming blackish on base of costa and stem of R. Anal lobe as broad as anal cell, r-m beyond middle of discal cell. Haltere. Yellow, becoming brown at base of stem. Legs. Entirely black, the coxae grey dusted; femora with rather long, pale hairs, tibia and tarsi with only a covering of minute setulae. Abdomen. Shining aeneous black, the disc of the tergites covered with relatively short, pale yellow hairs. Laterally the tergites are clothed with significantly longer, tawny yellow hairs, those on the down-curved lateral and ventral parts of the tergites conspicuously long and outstanding. Sternites also with long, outstanding hairs, rather paler than those on the lateral margins of the tergites. Genitalia. Large and bulbous, as large as the remainder of the abdomen, shining black and covered in long, outstanding tawny hairs, longest on the gonocoxite. Gonostylus long and sinuate, the tip outcurved, often visible without dissection.

Female. As male except as follows: slightly wider frons and rather shorter and less richly coloured abdominal hairs. Acrostichal row of hairs on the anterior of the mesonotum wider, 5–6 rows of hairs, wider than bare paramedian rows. Abdomen conical tapering to a rounded point. Furca pigmented apically with a long, drawn out blunt appendix, no vaginal plate, arms of furca almost in line with main part.

Discussion. The holotype of Usia anus Becker is no more than a diminutive specimen of U. vestita with rather sparser vestiture. It has a single original label, a small (now yellowing) rectangle of paper with “ Alger ” handwritten in ink, probably in Bigot’s own hand. Interestingly there is an almost identical label in the same hand on a female specimen of U. vestita in the Bigot collection. It seems likely that the holotype of U. anus and the U. vestita specimens in the Bigot collection in the OUMNH are part of the same series. The genitalia of the male holotype of U. anus are identical to those of U. vestita .

The four specimens in the Bigot collection at OUMNH listed in Evenhuis & Greathead (1999) as syntypes are unlikely to have been part of Macquart’s original series in MNHN. The labels on the OUMNH specimens, in Bigot’s hand, give “ Alger ” [ Algiers] as the collecting locality. The Lucas specimens in MNHN described by Macquart were from Oran and environs ( Lucas 1849: 453), some 400 km to the west. Further, there are no Macquart labels on the OUMNH specimens, just Bigot’s locality labels. As Bigot sent his collection to Macquart to describe in the 1850s, after Macquart’s description of vestita , it is improbable that any Macquart types described before 1850 would be in the Bigot collection (A.C. Pont, pers. comm.).

Distribution. Only known from northern Algeria. The Macquart specimens were collected by or on behalf of H. Lucas during the Algerian Scientific Expedition between 1838 and 1841 ( Evenhuis 2012). The Bigot specimens could also be Lucas specimens that Bigot obtained later as he did little or no collecting himself. During this study no later specimens were located, so it appears probable this species has only ever been collected by the Algerian Scientific Expedition. Data labels cite Algiers and Oran which, if accurate, suggest that this species was distributed along the coastal plain between the Mediterranean and the Atlas Mountains. However, Lucas and fellow collectors did venture inland bringing specimens back to the scientists based in coastal areas so these specimens could be from further inland ( Evenhuis 2012). This was clearly a rare or very local species even back in the mid-nineteenth century.