Borboroides atra Malloch

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 : 211-212

Borboroides atra Malloch

Figs 149–151

Borboroides atra Malloch, 1925: 85–86 , fig. 2.

Material examined. HOLOTYPE.!, New South Wales: Sydney , 1.xi.1924, “Health Dept.” ( AM, formerly in SPHTM, K83965 ). Head missing. Author’s determination label (in error): “ Borboroides australis Type Det J.R.Malloch ”; see Lee et al. (1956: 308) for comment.

Other material (localities only given). Queensland : Tinaroo Falls –Danbulla Road, Atherton Tableland ( ANIC) ; Wombye , near Nambour ( ANIC) ; Deception Bay ( ANIC) ; Mount Glorious ( AM, MHNG) ; Manorina (Mount Nebo) ( MHNG) ; Tamborine Mountain and vicinity ( AM, MHNG) ; Binna Burra , Lamington National Park ( ANIC) ; Box Forest Walk, Cunningham’s Gap, 28°03'S 152°23'E ( AM) . New South Wales : 20 miles [c. 32 km] E of Glen Innes ( ANIC) ; Mount Gibraltar National Park, 72 miles [c. 116 km] W of Grafton ( AM) ; Mount Kaputar , near Narrabri ( AM) ; Baradine ( ANIC) ; 7 miles [c. 11 km] E of Mendooran ( AM, CNC) ; Goonoo State Forest , 5 miles [c. 8 km] S of Mendooran ( AM) ; Lahey’s Creek Road, 12 km NW of Gulgong ( AM, USNM) ; Wongarbon Nature Reserve , 17 km SE of Dubbo ( AM, BM) ; Stroud ( AM, MHNG) ; Parkes ( AM) ; Mount Canobolas , near Orange ( AM) ; Doyle’s Creek , near Singleton ( AM) ; Myall Lakes National Park ( AM) ; Putty Road , 41 km N of Colo River bridge ( AM, NAT, TAU) ; Colo Heights ( AM) ; Blue Mountains (Mount Wilson, Katoomba, Lawson, Springwood) ( AM) ; Eugowra ( ANIC) ; Royal National Park , near Sydney ( AM, MNHG) ; Kanangra- Boyd National Park ( AM) ; Young ( ANIC) ; Minnamurra Falls , Kiama district ( ANIC) ; Shoalhaven River , near Braidwood ( ANIC) ; Clyde Mountain , Braidwood district ( ANIC) ; Durras Lake ( ANIC) ; 4 miles [c. 6 km] N of Bateman’s Bay ( ANIC) ; Wallaga Lake , near Bermagui ( ANIC) ; Brockelo’s Creek , 16.5 km S of Bermagui ( ANIC) ; Araluen ( ANIC) ; 4 miles [c. 6 km] E of Nimmitabel ( ANIC) ; Brown Mountain , Bega district ( ANIC) ; 3 km N of Wolumla, Merimbula district ( AM) ; Tantawangalo Forest , near Candelo ( AM) . Australian Capital Territory : Black Mountain, Canberra ( ANIC, MNHG) . Victoria : 7 km SW of Bruthen ( AM) ; Providence Ponds , 32 km W of Bairnsdale ( AM, MV) ; 6 km S of Beechworth ( AM, MV) ; Toolangi State Forest , 31 km S of Yea ( AM, MV) ; 11 km E of Warburton ( AM) ; 9 km E of Healesville ( AM) ; Pirron Yallock , 8 miles [c. 13 km] W of Colac ( ANIC) ; Mount William , Grampians ( AM) ; Wyperfield National Park , 47 and 51 km NW of Hopetoun ( ANIC) . Tasmania : Weldborough Pass ( AM, TDPI) ; 3 km NW of Saint Helens ( AM) ; 4 km NW of Bicheno ( AM) ; Forest Road , Orford ( AM) ; 3 km S of Copping ( AM) ; Mount Field National Park ( AM, TDPI) ; Ferntree , near Hobart ( AM) ; 8 km W of Geeveston ( AM) ; The Neck , Bruny Island ( AM) . South Australia : Ravine des Casoars, Kangaroo Island ( AM) .

Description (male, female). Very small blackish fly, agreeing with description of B. fimbria except as indicated below.

Coloration. Postfrons usually with some yellow to tawny coloration on anterior margin, otherwise with texture-pattern as given for B. fimbria ; cheek region usually partly yellowish to tawny anteriorly. Antenna with segment 2 tawnyyellow, segment 3 partly tawny-yellow, partly dark brown. Mesopleuron with posterior pruinescent zone becoming slightly diffuse at lower end. Halter, including capitellum, grey-brown. Abdominal tergite 6 of female grey-brown pruinescent except on bare black lateral zone.

Head. Height of cheek 0.24–0.39 of height of eye. Arista as long as greatest diameter of eye or almost so.

Thorax. Usually one distinct dorsocentral bristle present, or if short secondary dorsocentral present, it is close in front of major one; prescutellar acrostichal bristle absent or slightly differentiated. Hind femur usually with preapical dorsal bristle; hind tibia with subapical spur slightly shorter than greatest diameter of tibia, very slightly curved. Wing: apical section of vein 4 3.2–3.9 times as long as penultimate section.

Abdomen. Male postabdomen: tergite 6 undivided; spiracle 7 minute, but apparently open; epandrium shorter and more compact than in B. fimbria , with broad anteroventral bridge; surstylus with rather broad base, giving rise to: (a) stoutly rod-like main shaft with few, mostly short setulae and, on inner surface near apex, some stout, blunt spinules, and (b) an equally stout, rounded, outwardly inclined setulose tubercle (often evident even when surstylus is inflexed); lateral sclerite of hypandrium at inner end convex and embracing base of aedeagus, at outer end with setulose knob-like process against margin of epandrium, but with no other process or prominence; aedeagal apodeme free, significantly longer than in B. fimbria ; aedeagus with bulbous anterobasal part, not strongly sclerotized, but densely scabrous, with coarse denticles, dentate ridges, and, near base, dense pubescence, with partly sclerotized distal section from which arises a terminal largely membranous funnel containing gonopore and some ridging in throat; cerci broad, separate from each other, but broadly fused with epandrium at bases, there being no line of articulation for most of basal width, with narrowed, almost styliform apical prolongation and both small and large setulae.

Dimensions. Total length,? 1.2–1.4 mm,! 1.2–1.8 mm; length of thorax,? 0.54–0.69 mm,! 0.60–0.86 mm; length of wing,? 1.3–1.5 mm,! 1.4–1.9 mm.

Distribution. Queensland: most records from southeastern districts, one isolated record from tropics—Atherton Tableland. New South Wales: very widely distributed in eastern third of state. Victoria: apparently generally distributed. Tasmania: generally distributed at least in eastern districts. South Australia: Kangaroo Island—identification check from males desirable. We have found B. atra to be the most abundant species of Borboroides in most eastern Australian habitats.

Notes

Borboroides atra resembles other species of the atra group, having only one well-developed dorsocentral bristle, two long outwardly directed fronto-orbital bristles, and short but sclerotized distal section of vein 6. In most characters it resembles B. fimbria : both species share the possession of three separate large shining black zones on the postfrons. This condition is best appreciated in dry specimens under SLM with lighting arranged to show up the pruinescent areas. Borboroides atra differs from B. fimbria and all other species of this group in the largely greyish brown halteres, and, in the males, numerous characters of the postabdomen, including the long-acuminate cercus basally fused to the epandrium.

The holotype female of B. atra now lacks the head, but the present application of this name is justified by what remains of the specimen, together with the statement by Malloch that the frons is smooth and shining (at least in part).

Borboroides atra has often been collected by general sweeping, and also in large numbers around wombat dung baits and old carcasses.