Usia cornigera Gibbs

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 : 56-58

Usia cornigera Gibbs sp. nov.

( Figure 13 , Plate XIV)

Type material examined. HOLOTYPE; Morocco, Museum Paris, Maroc, Sidi Bettache , R. Benoit [sic] 1928/ May [♂ in MNHN] ; PARATYPES; Morocco, Tangier, April 1902, leg. Lord Walsingham [1♂ 1♀ in BMNH] ; Museum Paris, Maroc, Sidi Bettache, R. Benoit [sic] 1928/ May [2♂ 4♀ in MNHN] ; Meknès (550m.), R. Benoist 1919/ April [♂♀ in MNHN] ; Ain Leuh (1350m.), 65k Au S. de Meknès, R. Benoist 1919/ June [♀ in MNHN] ; Dar Kaid M’tougui, P. Pallary 1914 [♀ in MNHN ]; Rabat, 30 May 1934, Surcouf [♂ in MNHN].

Etymology. from Latin cornigera , “bearing a horn”, refers to the blunt apical elongations either side of the epandrium.

Diagnosis. A fairly large black, short-haired species of northern Morocco. All shining black, under natural light with a faintly bluish hue, all vestiture relatively short. Occiput shining and undusted on upper part, thinly grey dusted below, hairs on ocellar tubercle shorter than distance across frons at vertex, frons in front of anterior ocellus essentially glabrous. Mesonotal vestiture fairly short so fly does not have hairy appearance to naked eye, acrostichal setulae about as wide as this line of hairs. Marginal scutellar hairs much less than half median length of scutellum. Anepisternum mostly shining, a narrow band of dusting along posterior margin. Genitalia fairly large, epandrium longer than wide, apicolateral extensions distinctly longer than wide, truncate, usually visible in dried specimens; furca with tip pigmented, coming to a point.

Description. Measurements. Body length. 4.3–8.0mm. Wing length. 4.2–7.0mm.

Male. Head. Mouth-margin narrow, shining dark brown, obsolete below, almost as broad as palp at widest point. Frons shining brown-black, the frons longitudinally wrinkled posterolaterally, grey dusting laterally on anterior half. Frons narrowest at level of anterior ocellus, as wide as scape and pedicel together, about one fifth head width, lateral ocellus separated from eye margin by the longest diameter of that ocellus. Hairing relatively short, on ocellar area about as long as the distance across frons at vertex, yellowish brown, front half of frons glabrous or with minute setulae on dust spots. Occiput shining black above, thinly grey dusted centrally, becoming more densely grey-dusted on lower half. White hairs covering occiput similar to those on mesonotum, longer below. Ommatidia uniform in size across the eyes. Antennae black, third antennal segment longer than the scape and pedicel together, relatively narrow especially apically, all segments with very short setae above. Proboscis black, hairless, about as long as thorax and scutellum together; palps short, black with paler stem, clavate with pale hairs, the longest conspicuously shorter than the length of the palps. Thorax. Mesonotum and scutellum shining black except for a narrow area of light dusting on dorsal margin of post pronotal lobe, very narrowly along lower notopleural area and above the wings. Cuticle smoother between hair insertions slightly wrinkled posteriorly. Bare paramedian lines hardly apparent in some, quite evident in other specimens extending to mid-point of mesonotum, acrostichals in 4–5 irregular lines. Scutellum shining with shallow transverse wrinkles. Pleurae black with a covering of grey dust except anepisternum which is shining dark brown and undusted on at least anterior two thirds. Anterior of mesonotum covered with moderate length whitish hair, those on the disc of the mesonotum a little shorter than the width of the vertex, laterally longer. Rear of mesonotum and scutellum with conspicuously shorter hairs, barely overlapping. Posterior third of anepisternum and pronotum covered with rather longer whitish hairs. Wing. Wing membrane faintly brownish yellow tinged anteriorly and basally, fading to a grey cast posteriorly and apically, the veins pale brown, base of costa blackish. Anal lobe as broad as anal cell, r-m before middle of discal cell. Haltere. Yellowish white, becoming slightly brown at base of stem. Legs. Entirely dark brown to black, the coxae grey dusted; femora with the longest pale ventral hairs barely longer than half the greatest depth of a femur, tibia and tarsi with a covering of minute setulae only. Abdomen. Shining black, with faint bluish hue, roughened by tuberculate hair insertion most dense at the base of each tergite and tending to form pattern of transverse welts, the disc of the tergites covered with short, yellowish hairs only slightly overlapping each other. Laterally and on the down-curved margins the tergites are clothed with relatively longer, more whitish hairs. Sternites also with similar long, whitish hairs along their posterior halves. Genitalia. Prominent and conspicuous, fairly large, shining black the gonocoxite covered in long, whitish hairs similar to those on the lateral margins of the tergites, hairs on epandrium shorter. In dried specimens the elongated lateral corners of the epandrium are usually visible.

Female. As male except as follows: conspicuously broader oral margin, frons wider and grey dust spots more widely separated. Mesonotum and scutellar vestiture a little shorter. Abdominal hairs likewise shorter than in the male. Apical sternite rather square with small point in apical incision.

Discussion. Although with well differentiated epandrium and gonostylus, this species clearly belongs with the florea -group based on external features and the form of the aedeagus and female genitalia. Probably closest to Usia atrata Fabricius with which it shares a curved spur at base of gonostylus.

Distribution. So far only known from the northern half of Morocco. All the records are pre-WWII, despite its former wide distribution and significant field work in Morocco in recent years, no further specimens have come to light. It would now appear to be a rare species.

Figures

FIGURE 13. ♂ U. cornigera gonocoxite lateral view.