Borboroides corynetes, McAlpine, 2007

McAlpine, DK, 2007, Review of the Borboroidini or Wombat Flies (Diptera: Heteromyzidae), with Reconsideration of the Status of Families Heleomyzidae and Sphaeroceridae, and Descriptions of Femoral Gland-baskets, Records of the Australian Museum 59, pp. 143-219 : 198-200

Borboroides corynetes n.sp.

Figs 117–119

Material examined. HOLOTYPE.?, New South Wales: Rudy’s Road turn-off, 15 km N of Jenolan, 24.iv.2004, B.J.D. ( AM K219756 ). Mounted on card point after initial preservation in ethanol . PARATYPES. New South Wales: 29??, 4!!, same data as holotype ( AM, ANIC, USNM) ; 1!, 10 km SW of Ebor , 24.vi.1976, Z.R.L. ( ANIC) ; 2??, 1!, Mount Wilson, Aug. Sep. 2002, D.K.M. ( AM) ; 1?, 1!, Mount York, Blue Mountains , 6.vii.1986, D.K.M. ( AM) ; 1?, 3!!, Kanangra Road, 9.2 km S of Oberon – Jenolan Road junction, 26.iv.2004, B.J.D. ( AM) ; 1?, Black Springs fossicking area, Vulcan State Forest , c. 27 km SSW of Oberon, 4.v.2003, B.J.D. ( AM) ; 1!, Kunama, near Batlow , 11.viii.1961, D.H.C. ( ANIC) .

Other material. Tasmania: 1?, Tom Gibson Nature Reserve, 41°46'S 147°18'E, 29.iv.2004, M.F. ( AM); 1!, Lake Saint Clair , 14.ii.1964, A.L.D., M. D.M. ( ANIC) .

Description (male, female). Small to minute black fly with unmarked wings.

Coloration. Head, thorax, abdominal tergites, and sternites with general black ground colour. Postfrons entirely black or anteriorly dark brown, but without tawny anterior marginal zone, with dark grey pruinescence on most of surface except for a small subshining zone with very weak fingerprint sculpture lateral to each posterior ocellus, without shining median zone in front of anterior ocellus; face blackish with thick grey pruinescence and often narrow tawny zone on each side; cheek dark brown to blackish, without tawny zone, with narrow grey-pruinescent zone on lower margin. Antenna largely blackish; segment 3 with basal tawny zone on median surface. Prelabrum and palpus blackish, latter with well-developed grey pruinescence. Mesoscutum and scutellum thinly brown-pruinescent; mesopleuron grey pruinescent on upper margin and very broadly so on posterior margin so that pruinescence extends almost to centre; sternopleuron with grey pruinescence along much of upper margin; hypopleuron with grey to yellowish pruinescence anteriorly, usually glossy brown without pruinescence on posterior part or sometimes with trace only. Preabdominal tergites extensively grey-brown pruinescent, appearing black towards lateral margins when viewed from certain angles; in male, epandrium extensively thinly pruinescent, shining; in female tergite 6 entirely pruinescent.

Head higher than long; eye slightly longer than high; setulae on anterior half of postfrons variously inclined, those on either side of median line mostly incurved and inclined forwards; face with slightly raised median line, concave on either side; height of cheek c. 0.48–0.70 of height of eye; ocellar bristle at least as long as posterior fronto-orbital bristle; fronto-orbital bristles subequal in length, both strongly inclined and curved outwards. Antenna: segment 3 rounded, scarcely longer than high, normally slightly decumbent; arista slightly shorter than greatest diameter of eye; segment 6 with many short hairs on whole length. Prelabrum moderately small, not noticeably sexually dimorphic; palpus moderately short and slender.

Thorax stout; intradorsocentral setulae usually in four fairly regular rows; mesopleuron with few rather small setulae; the following thoracic bristles present: humeral, presutural, 1 + 1 notopleurals, supra-alar, postalar, 0 + 1 well-developed dorsocentrals but often a more anterior setula differentiated as a small second dorsocentral, two pairs of large scutellars, large posterior sternopleural and one or two small anterior ones; posterior intra-alar reduced to a setula. Fore femur with several posterodorsal and posteroventral bristles; mid femur with few anterior bristles of variable size; hind femur with preapical dorsal bristle; fore tibia without preapical dorsal bristle, unmodified in female, in male with ventral to posteroventral depression or excavation just beyond mid-length, ventral setulae well developed beyond depression, much less so basad of depression; mid tibia with pair of large approximated preapical dorsal bristles, one anterior bristle a little basad of these, and a ventral and an anteroventral subterminal spur; hind tibia with long preapical dorsal bristle and curved anteroventral subapical spur slightly shorter than greatest diameter of tibia. Wing as described for B. fimbria in most features; anterior crossvein meeting vein 4 at or distinctly before mid-length of discal cell; apical section of vein 4 3.2–4.2 times as long as penultimate section; anal crossvein straight or slightly curved, anal cell posterodistally somewhat obtuse or right-angled.

Abdomen. Sternite 1 well sclerotized across entire width; tergite 5 markedly shorter than tergite 4 in male, c. as long in female; sternite 5 in male almost as long as and much wider than sternite 4, with posterior marginal bristles, the outermost longest, in female similar to sternite 4. Male postabdomen: tergite 6 much reduced, medially desclerotized, consisting of two narrowly transverse plates; spiracle 6 well developed; thickened anterior band of sternite 6 heavily developed on each side, apparently symmetrical, with anterior lobe at each lateroventral angle; spiracle 7 not located; protandrial region of segment 8 stout, broadly sclerotized ventrally; with pair of prominent posterior condyles articulating with epandrium; epandrium almost ovoid, not much produced and attenuated at anterior foramen, with scattered setulae; surstylus, in lateral view, very oblique but not much broadened basally (though transversely broadened and tumid), with slender distal part inwardly and posteriorly directed from before midlength, thence becoming almost straight, with well-developed anterior setulae and numerous club-shaped spinules, many of them apically rounded, on inner surface and concentrated towards apex; lateral process of hypandrium particularly prominent with long setulae, one or two of them particularly long; basiphallus of aedeagus short, subcylindrical, with pair of posterior paramedian sclerotized strips; distiphallus large and inflated, largely membranous, but with extensive fine parallel rugosity, minutely hispid on distal surface anteriorly to posteriorly directed attenuate apex, at base with transverse sclerotized band on each side arising from apex of strip on basiphallus, these together corresponding to paired sclerotized triangles of B. shippi ; cercus extremely stout (broad and thick) flattened or explanate on terminal surface, densely pubescent, with some longer setulae. Female postabdomen: cercus elongate, with numerous fine setulae, apical ones longer.

Dimensions. Total length,? 1.5–1.6 mm,! 1.7–2.0 mm; length of thorax,? 0.59–0.78 mm,! 0.70–0.79 mm; length of wing,? 1.7–2.1 mm,! 2.2–2.3 mm.

Distribution. New South Wales: widely distributed in highlands. Tasmania: few records, including lowlands and highlands.

Notes

Among species of the atra group, B. corynetes agrees with B. gorodkovi and B. shippi in the extensively pruinescent postfrons with no median glabrous zone in front of anterior ocellus. Unlike those two species, B. corynetes has no yellow to tawny zone on the anterior margin of the postfrons and the palpus is darker, greyish brown rather than yellowish. In contrast to B. gorodkovi , B. corynetes has usually only one pair of dorsocentral bristles, or at most one rudimentary second pair, no prescutellar acrostichal pair, the pleural region has no grey-pruinescent line laterally bordering the fore-coxal foramen, and the subapical spur of the hind tibia is much smaller. Borboroides corynetes also differs from other species in its male genitalia, e.g., in the form of the surstylus; and the modification of the fore tibia in the male ( Fig. 119) is unique in the genus.

Most of the specimens collected by B.J.D. and D.K.M. were around wombat dung baits.

The specific epithet is a Greek noun meaning club-bearer, in reference to the armature of the surstylus.