Borboroides fimbria, 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 : 203-205

Borboroides fimbria n.sp.

Figs 11, 12, 125–129

Material examined. HOLOTYPE.?, New South Wales: Mount Wilson [Blue Mountains; Waterfall Reserve, c. 900 m, 33°31'S 150°23'E], 20.ix.2002, D.K.M. ( AM K219758 ). Mounted on card point . PARATYPES. New South Wales: 96??, 48!!, Mount Wilson, March, April , May , Aug., Sept., Oct. 1957 –2003, D.K.M. ( AM, ANIC, BM, CNC, USNM) .

Other material (localities only given). New South Wales: 4 miles [c. 6 km] S of Coolongolook, Nabiac district ( ANIC); 5.4 km NNE of Stroud ( AM); Tinda Creek, Putty Road ( AM); Putty Road, 41 km N of Colo R. bridge ( AM); Colo Heights ( AM); Euroka Clearing, 6 km S of Glenbrook ( AM); Kanangra Road, 14.2 km S of Jenolan–Oberon road junction ( AM); Boyd R. crossing, Kanangra-Boyd National Park ( AM, NAT, TAU); Otford ( AM); Minnamurra Falls ( AM, ANIC); Araluen ( ANIC); Tantawangalo Forest, near Candelo ( AM). Victoria: Nowa Nowa ( AM); 7 km S of Bruthen ( AM, BM); Providence Ponds Reserve, 32 km W of Bairnsdale ( AM); Toolangi State Forest, 31 km S of Yea ( AM, MV, USNM); 11 km E of Warburton ( AM, MNHG); Dom Dom Saddle, 17 km NE of Healesville ( AM); near Mount Juliet, 9 km E of Healesville ( AM, ANIC, MV); Myer’s Creek, near Healesville ( ANIC). Tasmania: Marakoopa Caves, near Mole Creek ( AM); Weldborough Pass ( AM); Mount Field National Park (including Russell Falls) ( AM); Ferntree, near Hobart ( AM); 8 km W of Geeveston ( AM, ANIC, TDPI); northern foot of Hartz Mountains ( AM); 3 km S of Barnes Bay, Bruny Island ( AM); The Neck, Bruny Island ( AM); Gilham’s Beach, Recherche Bay ( AM).

Description (male, female). Small to minute blackish fly with unmarked wing.

Coloration. Head, thorax and abdominal tergites black. Postfrons black, sometimes narrowly tawny on anterior margin, without distinct fingerprint sculpture, with dark greyish pruinescence except on three large glossy zones— ovate median zone extending from anterior ocellus to c. 0.6 of distance to ptilinal suture and pair of well defined lateral zones extending well in front of anterior ocellus but not so far forward as median zone, truncated anteriorly, separated from median zone by distinct, narrow pruinescent stripe; lower margin of cheek narrowly grey-pruinescent. Antenna dark brown; segment 3 with diffuse tawny basal zone. Prelabrum black; palpus tawny to tawny-brown. Mesoscutum and scutellum thinly brown-pruinescent; mesopleuron largely shining brown-black, with narrow grey-pruinescent zone on upper and posterior margins, on latter markedly narrowed below; sternopleuron usually with trace only of upper marginal pruinescence, mainly near bristle; hypopleuron shining brown to blackish, with zone of yellowish pruinescence anteriorly and posterior zone of grey pruinescence extending approximately to posterior margin. Legs brown; fore coxa largely dull yellowish, with dense pale pruinescence on anterior surface. Wing membrane faintly uniformly smoky; veins brown. Halter brown, with pale yellow capitellum. Abdominal tergites in male with grey-brown pruinescence except for variable glossy zone on lateral margins of tergites 4 and 5; in female tergites with brown pruinescence except on large lateral zones of tergites 3 and 4, tergite 5 largely glossy, with slightly variable greypruinescent zones on median line and on anterior margin; tergites 6 and 7 entirely dark grey-pruinescent.

Head much higher than long; eye subcircular or slightly higher than long; postfrons with setulae on anterior half mostly inclined forwards and mesad; face concave; height of cheek 0.25–0.36 of height of eye; ocellar bristle as long as posterior fronto-orbital; postvertical bristle nearly as long as posterior fronto-orbital; anterior fronto-orbital bristle slightly shorter than posterior one, directed outwards. Antenna: segment 3 decumbent, rounded, very slightly longer than high; arista slightly shorter than greatest diameter of eye; segment 6 with many short hairs no longer than diameter of segment 5. Prelabrum small in male, larger and broadly anteriorly prominent in female; palpus moderately short and slender.

Thorax stout; intradorsocentral setulae in two to three pairs of irregular rows anteriorly, sparser posteriorly; mesopleuron with few short posterior setulae; the following thoracic bristles present: humeral, presutural, 1 + 1 notopleurals, supra-alar, postalar, 0 + 1 well-developed dorsocentrals, two pairs of large scutellars, large posterior sternopleural and sometimes small anterior one; posterior intra-alar small or undifferentiated. Fore femur with about four posteroventral bristles and few variably developed posterior to posterodorsal bristles; mid femur with a series of c. 4–6 anterior bristles; hind femur with preapical dorsal bristle present or absent; fore tibia without distinct preapical dorsal bristle; mid tibia with usual pair of approximated preapical dorsal bristles, one anterior bristle a little basad of these, and an anterior and a ventral subapical spur; hind tibia with distinct preapical dorsal bristle and curved anteroventral subapical spur c. as long as tibial diameter. Wing: costa without special armature, noticeably weakened just beyond humeral crossvein; subcosta not conspicuously weakened at that level, sclerotized for some distance beyond, obsolete on c. distal third of length of second costal cell; anterior crossvein meeting vein 4 slightly before mid-length of discal cell; vein 2 distally almost parallel with vein 3, though often slightly curved; apical section of vein 4 3.6–4.7× as long as penultimate section; basal crossvein very oblique, aligned with penultimate section of vein 5, which is strongly curved; anal cell posterodistally somewhat acute to rightangled; distal section of vein 6 c. as long as anal crossvein or slightly longer.

Abdomen. Tergite 5 almost as long as tergite 4 in male, slightly longer in female; sternite 5 shorter than preceding sternites and undivided in male, markedly longer in female; sternite 1 sclerotized on whole width. Male postabdomen: protandrium approximately symmetrical; tergite 6 undivided, narrowly transverse, with spiracle just below each lateral margin; compound protandrial sclerite (synsternite 6–8) with narrow anterior marginal darkly pigmented annular band (largely representing sternite 6) encircling abdomen, with pair of short anteroventral spur-like extensions (as in B. atra ); sternite 7 broad, densely microtrichose ventrally, partly divided by narrow desclerotized ventral zone, completely fused with sternite 8 to form slender, curved, completely sclerotized tube, with pair of slender posterior condyles for articulation with epandrium; epandrium almost ovoid, not produced and attenuated at anterior foramen, on posterior surface desclerotized medially on c. posterior two thirds of length, with scattered short setulae; anteroventral bridge occupying more than one third of length of epandrium; prehypandrial membrane with minute microtrichia mostly grouped into very small combs; surstylus stoutly rod-like, almost straight, broadened basally, rounded apically, with sparse small setulae and few very long anterior ones, with short blunt spines crowded on inner surface near apex; lateral hypandrial sclerite with rounded process at epandrial end bearing several fine setulae and one very long setula; aedeagus stout, with basiphallus reduced to a sclerotized annulus; anterior surface of distiphallus with many fine, sharp transverse ridges, much of posterior surface covered by a brown sclerite, clustered surface filaments absent; gonopore terminal; aedeagal apodeme long, slender; cerci separate from each other and from proctiger, articulated with epandrium on membranous line, each large and broadly rounded, with many setulae and mollisetae, some of distal mollisetae on posterior surface very long and forming conspicuous fringe. Female postabdomen abruptly narrowed from segment 6; tergite 6 undivided, with straight posterior margin; sternite 6 also undivided; cercus elongate, obtuse, but not at all thickened apically.

Dimensions. Total length,? 1.1–1.5 mm,! 1.2–1.8 mm; length of thorax,? 0.53–0.75 mm,! 0.62–0.81 mm; length of wing,? 1.4–1.8 mm,! 1.6–2.0 mm.

Distribution. New South Wales: widely distributed from Nabiac district southwards, but not extending as far inland as B. atra and some other species. Victoria: widely distributed in eastern half of state. Tasmania: widely distributed. Borboroides fimbria is among the most abundant species of Borboroides in New South Wales, Victoria, and Tasmania, apparently particularly but not exclusively in natural wombat habitats.

Notes

Borboroides fimbria can be distinguished among other species of the atra group with only one dorsocentral bristle and pale yellow capitellum by the three separate shining black zones, all of which extend in front of level of anterior ocellus, on the otherwise pruinescent postfrons, the ventrally much narrowed pruinescent zone on the posterior margin of the mesopleuron, and the moderately large anteroventral subapical spur on the hind tibia. In the male the large, platelike, conspicuously long-fringed cercus is diagnostic, and in the female the complete median pruinescent zone on the full length of tergite 5. Females and males with retracted genitalia can be slightly difficult to distinguish from related species, e.g., B. bulberti and perhaps B. acumen .

Borboroides fimbria has been collected in large numbers around wombat dung baits, but is also attracted to kangaroo dung and various old vertebrate carcasses.

The specific epithet is a Latin noun meaning a fringe or element of a fringe, in reference to the fringed cercus of the male.