Usia maghrebensis 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 : 54-56

Usia maghrebensis Gibbs sp. nov.

( Figure 14 , Plate XIII)

Usia n. sp. Becker, 1906b: 207.

Type material examined. HOLOTYPE; Algeria, Lalla Marnia, 11 May 1910 / Museum Paris, ex coll., Hesse [♂ in MNHN] . PARATYPES; Algeria, Oran U. vicina Ex coll. Bigot [1♂ 1♀ in OUMNH] ; Museum Paris, Algérie, Lalla-Marnia, A. Finot 1897/ 29 May [18]80 [♀ in MNHN] ; Lalla Marnia, 11 May 1910 / Usia atrata Fabr. / Museum Paris, ex coll., Hesse [1♂ 3♀ in MNHN] ; Aïn-Séfra, Algérie, Coll. Fagniez/ Museum Paris, ex coll., Hesse [5♀ in MNHN] ; Aïn-Séfra, ( Oran), L. Bleuse/ Pres. by, E. Brunetti, Brit. Mus., 1927-184 [2♂ 1♀] . Morocco, Museum Paris, Maroc, Ain Leuh (1350m.), 65k Au S. de Meknès, R. Benoist 1919/ June [♂2♀ in MNHN] ; Mogador, Coll. J. Surcouf 1919 [♂♀ in MNHN] ; Sud Ozanais/ Museum Paris, Coll. J. Surcouf [2♂ in MNHN ].

Other material examined. Morocco, Tanger-Tetouane, El Biutz, N35.89468 W5.46781, 150m, 22/ May 2012, leg. Dils-Faes [3♂]; 18 May 2012 [2♂] ( PCJD).

Etymology. from the Arabic “ al-Maghrib ” referring to the region of northwest Africa where this species occurs.

Diagnosis. A fairly large black species with relatively long vestiture found in Morocco and Algeria. Shining black, usually without coloured reflections, occiput shining and undusted above, thinly dusted below, hairs on ocellar tubercle longer than width across lateral ocelli, front half of frons with only short setulae. Mesonotal vestiture long, all acrostichals reclinate, marginal scutellar hairs as long as mid-length of scutellum or almost so. Mesonotum dusted on anterior slope laterally, anepisternum entirely dusted. A few hairs in middle of katepisternum. Ventral hairs on hind femora not as long as femora is deep. Wing membrane clear, veins largely yellow. Genitalia relatively large, with epandrium apically with yellow rim, gonocoxite with yellow areas, surmounted by a brush of golden hairs usually easily seen in pinned specimens; furca with tip unpigmented, membranous.

Description. Measurements; Body length. 5.5–8.5mm. Wing length. 5.0–7.0mm.

Male. Head. Mouth-margin narrow and linear no wider than the tip of the palps, shining black, just evident below. Frons and upper part of occiput shining black, central and lower part of occiput thinly grey dusted. The frons rather shagreened and wrinkled, grey dusting laterally on lower half, the dust spots separated by an undusted area about one third of the frons width at this point. Frons narrowest level with anterior ocellus, no more than a fifth head width, lateral ocellus separated from eye margin by about the diameter of that ocellus or a little more. Hairing long but not exceptionally so, on ocellar area about as long as distance between lateral ocelli or a little more, often with hairs extending onto lateral part of frons either side of anterior ocellus, pale yellow. Ommatidia uniform in size across the eyes. Antennae black, third segment longer than the scape and pedicel together, all segments with pale brownish hairs above. Proboscis black, hairless, shorter than 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 on anterior slope laterally, on post pronotal lobe, sparingly on notopleuron and above wing. Smooth except for hair insertions, front third of mesonotum with bare paramedian lines as broad as midline which has 3–4 lines of hairs. Hind part of mesonotum slightly roughened, scutellum shallowly, transversely wrinkled. Pleurae black with a thin but conspicuous covering of grey dust not entirely obscuring the ground colour. Mesonotum, scutellum and posterior half of anepisternum covered with long, rather shaggy hairs (similar to U. atrata Fabricius or U. pubera Strobl ) hairs on the margin of the scutellum the longest, almost as long as length of scutellum. Hair very pale yellow to whitish. A scattering of pale hairs on the pronotum and middle of katepisternum. Wing. Wing membrane clear, faintly yellow tinged basally, the veins yellow to brown, subcosta and base of stem of R yellow. Anal lobe as broad as anal cell, with evenly curved posterior margin, r-m just before to just beyond middle of discal cell. Haltere. Yellow, becoming brown at base of stem. Legs. Entirely black, the coxae grey dusted; coxae and femora with rather long, pale hairs, ventral hairs of hind femora exceeding width of tibia but not greatest depth of femora, tibia and tarsi with a covering of minute brown setulae. Abdomen. Shining aeneous black, the disc of the tergites covered with relatively short, pale yellow hairs,. Laterally and on the downcurved margins the tergites are clothed with longer, rather shaggy whitish-yellow hairs (similar to U. vestita Macquart but the hairs conspicuously shorter and paler). Sternites also with similar long, pale whitish hairs. Genitalia. Large and protuberant, almost as large as the remainder of the abdomen, shining black, variably yellow on apicomedial and internal part of gonocoxite. Epandrium densely covered with short, apically curved pale yellow hairs, apical rim narrowly yellow. Gonocoxite with longer pale hairs similar to those on the lateral margins of the tergites, especially the apical corners which are furnished with a relatively dense brush of inwardly curved golden yellow hairs. Gonostylus similar to that of U. accola Becker (a short-haired species) but often not visible in pinned specimens.

Female. As male except as follows: noticeably wider frons and the lateral ocellus separated from the eye margin by conspicuously more than the diameter of that ocellus. Abdominal hairing rather shorter, especially laterally. Abdomen conical tapering to a rounded point, apical sternite with basal raised boss and often apical ridge, longer than broad; furca with tip pointed but unpigmented, membranous, arms short and broad.

Discussion. This species clearly falls within the U. florea group, being most closely allied to U. accola Becker that occurs further east in the Maghreb and does not overlap in range.

Becker (1906b) recognised this as a distinct species based on two specimens in the Bigot collection from Oran (now in OUMNH) writing that they were close to U. atrata Fabricius (= U. claripennis of Becker) but with a much larger hypopygium. However, he declined to name them or include them in his key stating that it would first be necessary to make detailed comparative drawings of the genitalia of this and related species.

Distribution. Western Algeria and the northern half of Morocco. Most specimens seen are over 80 years old, none being collected recently until four males found by Jos Dils near Tangiers in 2012. Would appear to be very uncommon and has probably declined since the beginning of the 20th century.

Figures

FIGURE 14. ♂ U. maghrebensis gonocoxite lateral view.