Borboroides stewarti, 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: 162-164
treatment provided by
Borboroides stewarti n.sp.
Figs 20, 21, 26–35
Material examined. HOLOTYPE?, New South Wales : Mount Wilson [Blue Mountains; Waterfall Reserve, c. 900 m, 33°31'S 150°23'E], 6–7.v.2002, D.K.M. ( AM K219743). Mounted on card point GoogleMaps . PARATYPES. New South Wales : 47??, 51!!, Mount Wilson , March , April , May, June, Oct. 1957 –2002, B.J.D., K.C.K., D.K.M. ( AM, BM, CNC, USNM) ; 3??, 2!!, 26–27 mi. [c. 42–43 km] from Glen Innes , Glen Innes to Grafton Highway [ Gibraltar Range vicinity], April 1970, D.H.C. ( ANIC) ; 2??, Mount Kaputar National Park [Narrabri district], May 1984, K.C.K. ( AM) ; 1?, Wright’s Lookout , New England National Park, March 1961, D.K.M. ( AM) ; 1!, Barrington House , 92 km NE of Singleton [Williams River near Salisbury], June 1976, Z.R.L. ( ANIC) ; 4??, Kanangra Road , 14.2 km S of Oberon – Jenolan Road junction, April 2002, B.J.D., D.K.M. ( AM) ; 1?, 2!!, 2 mi. [c. 3 km] SW of Tumorrama [ Tumut district ], June 1964, G.L.B. ( AM) ; 1!, Monga [Braidwood district], July 1962, D.H.C. ( ANIC) ; 4??, 3!!, 5 mi. [c. 8 km] S of Monga , May 1968, D.H.C., Z.R.L. ( ANIC) ; 1?, 1!, Mongarlowe River , Clyde Mountain, May 1965, D.H.C. ( ANIC) ; 1?, Cabbage Tree Creek , Clyde Mountain, May 1965, R.L. ( ANIC) ; 3!!, Araluen , Aug. 1982, Z.R.L. ( ANIC) . Australian Capital Territory : 3??, 3!!, Mount Coree, April 1968, D.H.C. ( ANIC) ; 1?, 2!!, Blundells Creek , April, Oct. 1987, D.H.C. ( ANIC) ; 3??, Bull’s Head , March, April 1968 –1969, D.H.C., Z.R.L. ( ANIC) ; 1?, Honeysuckle Creek , April 1985, I.D.N., J.C.C. ( ANIC) .
Other material (localities only given). Victoria: Toorloo Arm, Lakes Entrance ( ANIC); Fernshaw, near Healesville ( AM); Mount Donna Buang, near summit ( AM, MV).
Description (male, female). Moderately elongate, largely tawny fly with darker markings on thorax and legs; size large for the genus.
Coloration. Head tawny-yellow; postfrons largely dull, pruinescent, with small shining or subshining zones on each side of posterior ocelli and immediately in front of anterior ocellus; posterior part of postfrons suffused with brown; ocellar spot brown to black; occipital region suffused with brown to blackish on much of upper half. Antennal segment 3 suffused with grey-brown distally. Prelabrum and palpus yellow, sometimes darker in female. Thorax yellowish tawny; mesoscutum with generally complete median brown stripe extending on to scutellum, and variable lateral brown zone; pleura, including hypopleuron, almost entirely pruinescent except for small shining anteroventral zone on mesopleuron; upper part of pleura with variable brown zone, usually extending from near prothoracic spiracle to pleurotergite. Legs tawny, often with variable degree of brown suffusion on femora and tibiae; hind femur dark brown distally to variable extent. Wing yellowish hyaline, unmarked. Halter yellow, capitellum often paler. Abdomen brown to tawny-brown, often darker in female.
Head much higher than long; eye slightly higher than long; postfrons with setulae on anterior half mostly inclined forwards and mesad, more numerous towards ptilinal suture; junction of postfrons and face forming acute angle in profile in male, not angular in female; height of cheek 0.29–0.47 of height of eye (ratio higher in females); ocellar bristle longer than posterior fronto-orbital bristle; postvertical bristle slightly shorter than posterior fronto-orbital; anterior frontoorbital bristle reclinate, less than half as long as posterior fronto-orbital, sometimes vestigial. Antenna approximately porrect; segment 2 small, with very oblique distal articular surface; segment 3 c. 1.6× as long as deep, larger in male than in female; arista slightly longer than greatest diameter of eye; segment 6 with many short hairs no longer than greatest diameter of segment 5. Prelabrum moderately large in female, narrower and shallower in male; palpus moderately short and narrow.
Thorax somewhat slender; mesoscutum c. as wide as long or almost so; intradorsocentral setulae in c. two pairs of irregular rows; mesopleuron without setulae; the following thoracic bristles well developed: humeral, 1 + 1 notopleurals, presutural, supra-alar, postalar, posterior intra-alar, three dorsocentrals, of which first distinctly behind suture, about as long as second and distinctly shorter than third one, one sternopleural; prescutellar acrostichal bristle absent. Fore leg without stridulatory modification; fore femur with several long anterodorsal and usually slightly smaller anteroventral bristles; mid femur with a series of anterior bristles from just beyond mid-length, also, in male only, with a series of strong posteroventral bristles; hind femur with one large anterodorsal bristle near distal quarter and, in male only, with subapical posteroventral excavation preceded by a series of numerous posteroventral bristles; mid tibia straight, slightly more slender in male, with usually two anterior bristles, one anterior and one posterior subapical spur, with large subapical ventral spur in female, none in male, without mollisetae or particularly enlarged hairs in either sex; hind tibia without subapical anteroventral spur, that of male only attenuated and strongly curved on c. basal quarter. Wing: humeral break of costa and corresponding break of subcosta indistinct; subcosta entirely sclerotized and pigmented to junction with costa; vein 2 distally almost parallel with vein 3 though slightly curved; apical section of vein 4 1.8–2.3× as long as penultimate section; section of vein 5 on discal cell almost straight or almost imperceptibly arched; discal cell very elongate (compared with that of B. atra and related species); basal crossvein oblique, but meeting penultimate section of vein 5 at marked angle; posterodistal angle of anal cell obtuse; distal section of vein 6 long, apically curved distad and fading out before reaching margin.
Abdomen. Sternite 1 reduced, represented by pair of separate lateral plates; in male, tergites 4 and 5 with particularly long lateral marginal bristles and sternite 4 with more numerous long bristles on each side, sternite 5 divided into two widely separated strongly setulose plates; in female, these sclerites without particularly long bristles, sternite 5 undivided, tergite 5 with anterior margin c. as broad as and fitted to posterior margin of tergite 4, not retractile beneath tergite 4. Male postabdomen: tergite 6 only indistinctly sclerotized; spiracle 6 in membrane but well removed posteroventrally from tergite 6, nearer to spiracle 7; protandrial synsternite elongate-ovoid, somewhat asymmetrical in general shape; sternite 6 with thickened anterior rim on left side, enclosing spiracle 7, which has strongly raised rim to form short projecting cylinder; semisclerotized broad tubercle present on right side of anterior part of ventral protandrial membrane; posterior part of ventral surface of protandrium (in front of sclerotized ventral bridge) with asymmetrical pair of sclerites—that on left side forming isolated plate with numerous strong, minutely serrated ridges and no spinules nor microtrichia, that on right side connected to synsternite, without ridges, with group of c. nine erect blunt spinules and few microtrichia, some of which are similarly blunt; epandrium very broad, but asymmetrically attenuated at base, with many setulae, some dorsal ones longest; anteroventral bridge of epandrium well developed; surstylus large, with complex array of lobes, and combs and fascicles of setulae and spinules as in Fig. 32; gonite very broad, basally narrowed, its distal margin anteriorly with single series of stout blunt to subacute spinules, posteriorly with dense, non-seriate longer, finetipped spinules, its inner surface with additional lobe bearing numerous spinules distally; aedeagus with sclerotized slightly clavate, slightly scabrous basiphallus, and with pair of slender lateral horn-like processes; distiphallus bulky, tapered near terminal gonopore, arising from anterior surface of basiphallus, with many small scale-like processes except near apex; cerci connected only at bases, slightly narrowed and truncate apically (in posterior view), each with an outer marginal series of stout setulae only; proctiger bituberculate, with thick dorsally directed pubescent process. Female postabdomen not abruptly narrowed; tergites 4, 5, 6, 7 gradually sequentially decreasing in size; cercus rather short and stout, with moderately short setulae.
Dimensions. Total length,? 2.3–3.3 mm,! 2.5–3.4 mm; length of thorax,? 1.1–1.5 mm,! 1.2–1.6 mm; length of wing,? 3.5–4.4 mm,! 3.4–4.5 mm.
Distribution. New South Wales: cooler areas from Glen Innes district southwards. Australian Capital Territory: ranges W of Canberra. Victoria: areas E of Melbourne.
Borboroides stewarti has the characters of the stewarti group as given above. Within the group it agrees particularly with B. musica in having the thorax yellowish tawny with few brown markings. It is distinguished from B. musica by having the anterior fronto-orbital bristle very small and not proclinate and, under high magnification, by the absence of the stridulatory organ on the fore coxa and femur; also in the female by the much less reduced abdominal tergite 5, and in the male by the strongly curved basal part of the hind tibia and the comb-like series of strong posteroventral bristles on the mid femur.
Adults are attracted to wombat dung, and are most frequently collected in the autumn.
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