Sobarocephala triangula, spec. nov.

Sobarocephala triangula spec. nov.

Figs 26, 63–65

Description (Fig. 26). Male. Body length 2.8mm. Arista densely plumose with hairs sparser apically. Setae light brown. Ocellar seta thin and half length of postvertical seta. Presutural intra-alar seta absent. Two dorsocentral setae. Acrostichal seta absent. One pair of lateral scutellar setae. Head yellow with dorsal stripe on first flagellomere light brown and ocellar tubercle brown; gena and parafacial pilose. Scutum yellow with one pair of wide postsutural notal stripes. Scutellum yellow with lateral corner brown. Metanotum yellow. Pleuron white with anepisternum yellow (sutures brown) and anepimeron brown. Legs light yellow with coxae white. Halter entirely white. Wing dusky on distal ¼. M1+2 ratio 3.8. Abdomen brown to tergite 6, with remainder yellow.

Female. Australian paratype as described for male except as follows: length 3.9mm; setae brown; notal stripes wider and more broadly rounded; metanotum brown lateral to scutellum (fading medially); pleuron yellow with anepisternum and anterior margin of anepimeron brown; fore tibia and tarsi brown; stripe on first flagellomere strong; face orange; parafacial, gena, occiput and lower half of back of head light yellow. Wing dusky with anterior margin darker. Abdomen brown with segment 8 and terminalia yellow.

Male terminalia. (Figs 63–65) Annulus well-developed, enclosing 7th spiracle. Surstylus half height of epandrium, tapering at apex, and with relatively long, pointed tubercles densely arranged on distal half of innerposterior margin; inner-medial surface with single straight oblique row of tubercle-like setae. Cerci large and triangular with apex pointed. Hypandrial lobe with one long medial and two minute distal setae. Pregonite subclavate with two distal setae. Phallapodeme and basiphallus well-developed. Epiphallus with anterior margin strongly projecting ventrally. Postgonite small with two apical setae. Distiphallus slightly more than half length of phallapodeme; paraphallus small with irregular outline.

Variation. Vietnamese female as described for Australian female except as follows: length 4.8mm; scutum with presutural markings (dotted line on figure); pleuron brown with ventral margin white; fore tibia paler; clypeus orange medially; tergites 1 and 5 yellow; tergite 7 with posteromedial spot. ANIC female (only tentatively assigned to this species) similar to Australian paratype except arista short plumose, first flagellomere entirely yellow and wing dusky along anterior margin.

Etymology. The specific name refers to the approximate outline of the notal stripes and the unusual shape of the male cerci.

Holotype: INDONESIA. Sumatra, Aceh Gunung Leuser Nat. Pk., Ketambe Res. Sta., 1–28.ii.1990, per. D.C. Darling, 1° rainforest, mature forest, Terrace 4, light gap, 400m, 3°41’N, 97°39’E, Malaise trap head (1♂, ROME).

Paratypes: AUSTRALIA. NT: Cahill’s Crossing, East Alligator R., 24.ii.1996, D.K. McAlpine & G.R. Brown (1♀, AMSA). VIETNAM. Nghê An: W. Con Cuông, Khe Moi forestry camp, Malaise, open meadow, 18°56’N, 104°49’E, 26–30.x.1994, D.C. Currie (1♀, ROME).

Additional material examined: AUSTRALIA. QLD: Mt. Glorious, 21.x.1982 – 13.i.1983, Malaise, A. Hiller (1♀, ANIC).

Comments. This widespread and variably-patterned species is the only Sobarocephala known from Australia, and the only Indoaustralian species with a medially yellow scutellum, aside from the Laotian S. nebulosa and S. anonymos. Considering the broad geographic distribution and colour variations of S. triangula, as well as its unusual southern occurrence, additional study is required to more confidently delimit the boundaries and definition of this species, particularly to confirm the identity of the Australian populations known from only two females.