Megaselia russellensis, DISNEY, 2003

DISNEY, R. H. L., 2003, Tasmanian Phoridae (Diptera) and some additional Australasian species, Journal of Natural History 37 (5), pp. 505-639 : 581-584

Megaselia russellensis sp. nov.

(figure 41)

Material

H  : male, Tasmania, Mount Field National Park, Russell Falls , 11 January 1992 ( R. H. L. Disney —25-9) ( TMH).

P    : male—as holotype except ( UMZC).

Etymology Named after the type locality, Russell Falls.

Diagnosis

The combination of bare mesopleuron; four subequal bristles on scutellum; differentiated anterodorsal, spine-like, hairs on hind tibia; brown abdominal tergites; short-haired arista; and antial bristles situated below anterolaterals; takes this species to couplets 8–10 on p. 84 of Borgmeier’s (1967b) keys. The distal two-thirds of haltere knob being pale yellow contrasts with the all brown knob of M. subnudiseta Beyer. The presence of vein Sc (‘mediastinalis’ of Borgmeier), albeit fading away before reaching R, contrasts with its lack in M. flavibasis Beyer. The new species 1

more closely resembles M. picta (Lehman) , but the latter has some bifid spines in apical comb of hind tibia and a different hypopygium (see figure 240 in Disney, 1989). Vein 3 forked; no SPS vesicles in third antennal segment; male labella densely spinose below; and only two bristles on notopleuron.

Male

Frons brown, broader than long and with dense, but very fine, microsetae. Antials almost directly below anterolateral bristles but about equidistant from them and from upper supra-antennals, which are about the same distance from ALs, which are a little higher on frons than upper SAs. Lower SAs subequal to or a little shorter than upper pair, which are more than twice as far apart. Pre-ocellars clearly closer together than upper SAs, but about as far apart as either is from mediolateral bristle, and distinctly lower on frons than mediolaterals. Five bristles on cheek and three longer ones on jowl. Third antennal segment brown, but not dark. Palps yellow with five to seven bristles, but three to five longer than rest. Pale brownish yellow labrum with greatest breadth only 0.8× that of third antennal segment. Labella pale dusky yellow, with dorsolateral brown bands, and somewhat enlarged. Thorax brown, but with paler areas laterally. Abdominal tergites with fine hairs, apart from those at rear of T 6 (figure 41) and two to four stronger ones at each side of T 2. Venter greyish yellow but from edges of tergites with descending grey bands that fade away below spiracles. Fine hairs below segments 3–6. Hypopygium yellowish brown to brown and as figure 41. Legs yellow apart from brown tip of hind femur and along dorsal edge of hind tibia. Front tibia with 9–11 anterodorsal small spines. Front basitarsus slender, all five segments with posterodorsal hair palisade and segments 4 and 5 subequal in length. Near-dorsal hair palisade of mid tibia extends about 0.9× length. Hairs below basal half of hind femur clearly longer than those of anteroventral row of outer half. Hind tibia with six to eight differentiated anterodorsals and six to eight stronger posterodorsals. Wings 1.7–1.9 mm long. Costal index 0.51–0.54. Costal ratios 2.64–3.70:1.93–2.57:1. Costal cilia 0.06 mm long. With six much longer axillary bristles. A minute hair at base of vein 3. Veins brown, the costa being palest. Membrane lightly tinged grey.