Austroleptis Hardy

Kerr, Peter H., 2010, 2592, Zootaxa 2592, pp. 1-133 : 70-71

Genus Austroleptis Hardy

Figs. 1, 3, 26, 41–42, 67, 87–88, 113, 135, 167.

Austroleptis Hardy 1920a: 126 . Type species Austroleptis rhyphoides Hardy 1920a , by original designation.

Diagnosis. Austroleptis is unique among lower brachyceran taxa in having the cornu apically setulose and by having sternite 8 of the female terminalia laterally divided into two segments. In the male genitalia, the presence of paired sclerotized lobes arising ventrally, near the center of the gonocoxites, is another autapomorphic development. Austroleptis is also characterized by the combination of having a recessed clypeus, female cercus one-segmented, M 3 missing, and male genitalia without gonocoxal apodemes. Although Austroleptis is not unique among lower brachycerans in having each these four features, the phylogenetic placement of the genus suggests that most, if not all, of these character states are each independently derived and represent additional autapomorphies for the genus. Within Tabanomorpha , Austroleptis is unique in having a recessed clypeus and is the only taxon outside of Athericidae and Tabanidae that has one-segmented female cercus. Nagatomi & Iwata (1976: 43) and Nagatomi & Nagatomi (1987: 140) state that Austroleptis is peculiar among Tabanomorpha in having sternite 9; they were mistakenly referring to the posterior sclerite of sternite 8. All lower brachyceran flies retain sternite 9 (also known as the genital fork, vaginal apodeme, or furca), in some form. Austroleptis is restricted to the southern hemisphere, in South America and Australia.

Austroleptis are small to moderately sized flies (3.1 to 7.7 mm) of black, brown, brown and black, orangish or yellowish coloration. There is sexual dimorphism in the coloration. Males are usually black or darker, whereas females often have at least some light brown or orange, if not entirely yellowish. All Australian Austroleptis have spotted wings, whereas South American Austroleptis wings are hyaline (although I have seen one undescribed Austroleptis species from Chile, Malleco Province, with infuscate wing veins). Antenna with basal flagellomere enlarged, oval, laterally compressed, bearing 2 to 4 distal flagellomeres; eyes in male holoptic; laterotergite bare; tibial spur formula 0:2:2 (spurs very short); and tibia without macrochaetae. Due to its unusual combination of character states (listed above) and its restricted distribution, Austroleptis is unlikely to be confused with related Diptera . In South America, it is most readily distinguished from Atherimorpha by its recessed clypeus, bare laterotergite and the absence of M 3 and from Litoleptis by the multisegmented flagellum, spurs on mid and hind tibia, and the presence of the discal cell. In Australia, it is most readily distinguished from Spaniopsis by its multisegmented flagellum and the presence of hind tibial spurs.

Description. Head. Clypeus not bulbous. Scape approximately same size as pedicel. Flagellomeres 3–5; first flagellomere enlarged, oval, laterally compressed, bearing setae; distal flagellomeres robust, cylindrical, short (except terminal flagellomere which is more elongated). Eyes inconspicuously setulose; in female, dichoptic; in male, holoptic, flattened dorsally, ommatidia split into dorsal and ventral areas and smaller ventrally. Labella with pseudotracheae, longer or shorter than palpus. Theca elongate, lateral sclerites tightly adjacent, apparently fused with suture. Palpus two-segmented; proximal and distal segments subequal in length. Stipes surrounded by membrane above theca, directed posteriorly (very reduced). Cardo not swollen. Lacinia longer than palpus, lacinia apex not serrated. Mandibles absent. Cibarial pump short, as wide as long or wider. Cornu shorter than cibarial pump. Pharyngeal pump narrow along most of length, mostly flat; longer than length of cibarial pump.

Thorax. Mesonotum with vittae. Dorsocentral bristles absent, all dorsal setae of equal length or variable (as in A. collessi ). Anepisternum bare. Laterotergite bare. Postspiracular scale absent. Proscutellum present. Subscutellum enlarged. Wing hyaline or lightly infuscate, membrane with or without markings, with or without pterostigma. Lower calypter reduced. Upper calypter well developed, with broad curvature, lobe-like, width twice length or less. Costa extends to wing tip or past wing tip (to at least R 5). Humeral crossvein (h) well developed. Sc-r crossvein weakly developed, positioned distal to h by less than length of h. Dorsal side of R 1 setulose, ventral side with or without setulae; R 4 and R 5 with or without setulae; all cells and other wing veins bare. R 2+3 sinuous, apical third ultimately bends slightly anteriorly, toward leading edge of wing margin; shorter than R 5. Base of R 4 –R 5 fork proximal or directly above distal end of cell dm. R 4 at base relaxed, not strongly curved, nearly straight apically. R 5 anterior to, posterior to, or ending at wing tip; clearly longer than R 4+5 (r-m to R 4 origin). M 3 wing vein absent. Origin of CuA 1 at discal cell. CuA 2 reaches wing margin, about 2/ 3 length of posterior vein of cell bm. Alula with broad curvature, rounded evenly. Anal lobe well developed. Cell cu p closed. Halter knob between 1/3–1/2 length of stem. Tibial spur formula 0:2:2. Mid and hind tibial spurs short. Hind coxal tubercle absent. Hind tibial macrochaetae absent. Postmetacoxal bridge present as incomplete, thin extension.

Abdomen. Terminal abdominal segments 5–10 evenly tapered from segments 1–4. In female, tergite 7 much wider than long. Intersegmental membrane between segments 7 and 8 short, as throughout abdomen. Sternite 8 sclerite elongated; more than twice as long as wide; divided into two segments, anterior segment long and wide, posterior segment rounded, cupped. Male terminalia with epandrium simple, not containing hypandrium ventrally. Epandrium wider than long, modestly curved anteriorly. Tergite 10 absent. Hypoproct triangular (rounded posteriorly), flattened; anterior margin entire, evenly sclerotized; appearing posteriorly lobed, with paired region of increased sclerotization; setose. Cercus directly adjacent to epandrium; directly adjacent to one another, separation distance one quarter width of cercus or less; held horizontal in relation to rest of abdomen; in posterior view flat. Hypandrium fused entirely to gonocoxites. Gonocoxite smooth dorsally, without sinuous ridge leading to gonocoxal apodeme; ventrally, with paired, sclerotized, lobe-like processes. Gonocoxal apodemes absent. Lateral ejaculatory processes absent. Ejaculatory apodeme moderately long, reaching anterior margin of hypandrium. Ejaculatory apodeme laterally compressed, umbraculate (umbrella-shaped) anteriorly. Aedeagal tines absent. Endoaedeagal process absent. Female terminalia with three spermathecae, clubbed, lightly to well sclerotized. Spermathecal ducts more than three times but less than five times length of sternite 9, inflated at base of spermathecae. Spermathecal duct accessory glands absent. Ejection apparatus of spermathecal ducts sclerotized, with surface ringed furrows. Common spermathecal duct thickened, subequal in length to longest diameter of genital chamber. Genital chamber circular, small, occupying fraction of sternite 9 area. Accessory gland posterior to genital chamber inconspicuous, easily overlooked even after staining. Sternite 9 anterior end tapered to a point; posterior end with broad lateral extensions, free, held in vertical plane. Tergite 10 present. Tergite 10 narrow, split into two separate lateral sclerites; short (length less than half width). Sternite 10 roughly pentagonal, pointed posteriorly; almost entirely underneath cercal segments. Cercus one-segmented; separated from one another dorsally by approximate width of second cercal segment; without apical sensory pits.

Larva. Unknown (however, see below).

Biology. Austroleptis is usually confined to mountainous regions and is reportedly a visitor of flowers ( Colless & McAlpine 1991). At Cradle Mountain National Park, in central Tasmania, I collected Austroleptis multimaculata males and females on the leaves of flowering Richea scoparia Hooker , however I did not see the insects feed. Less is known about the South American members of this genus ( Nagatomi & Nagatomi 1987), which are rarely collected. Austroleptis larvae are uncharacterized, but have been reared inadvertently from rotting wood ( Colless & McAlpine 1991).

Literature. Paramonov (1962) provides a key to species for the Australian fauna. Nagatomi and Nagatomi (1987) provide a key to species for the Neotropical fauna.