Megaselia cercisetaria, DISNEY, 2003

DISNEY, R. H. L., 2003, Tasmanian Phoridae (Diptera) and some additional Australasian species, Journal of Natural History 37 (5), pp. 505-639 : 536-538

Megaselia cercisetaria sp. nov.

(figure 13A, B)

Material

H  : male, Tasmania, Mount Field National Park, Russell Falls , 11 January 1992 ( R. H. L. Disney —25-8) ( TMH).

P    : 10 males; 8 as holotype except some (25-9) and 2, 26 December 1991 (25-5) ( TMH, UMZC).

Etymology The name refers to the numerous hairs on the male cerci.

Diagnosis

The combination of scutellum with a pair of small hairs and a pair of bristles; mesopleuron with hairs but no bristles; costal index>0.44; no differentiated anterodorsals on the hind tibia; and brown halteres; will take this species to couplets 11, 13 and 15 on p. 206 of Borgmeier’s (1967a) keys; the divergence at couplet 11 being caused by variations in the costal index. The brown hind femur will at once distinguish it from M. canaliculata (Brues) . The costal cilia of M. atricornis Beyer exceed 0.18 mm but are <0.16 mm in M. cercisetaria . The wing of the latter is <2.4 mm long, but is> 2.5 mm in M. malaisei Beyer. The subsequently described M. turbata Borgmeier (1967b) runs to the same couplet, but has much stronger posterodorsals on the hind tibia. At couplet 15 the near-dorsal hair palisade of the mid tibia is less than two-thirds of length in the new species but at least three-quarters of its length in M. textilis Brues. Several subsequently described, mostly aquatic, species run to the same couplets, but the new species is readily distinguished by its distinctive hypopygium. The latter has a curious bilobed left hypandrial lobe,>10 hairs on each cercus, and a single strong bristle plus a few small hairs on the left side of the epandrium. The brown third antennal segment lacks SPS vesicles; yellow palps; mesopleuron with 7–25 hairs; notopleuron with three bristles; front basitarsus slender with long hairs below; hind tibia with 17–21 differentiated, but fine, posterodorsal hairs.

Male

Frons brown, wider than long, with dense but very fine microsetae. Four strong, subequal, supra-antennal bristles. Anterolaterals level with upper SAs but antials slightly lower and clearly closer to ALs. Pre-ocellars further apart than either is from a mediolateral bristle or all four bristles almost equidistant, and in a roughly straight transverse row or POs a little lower on frons. With three to five bristles on cheek and three or four stronger ones on jowl. Palps with seven or eight bristles, of which two to four are longer and stronger than rest. The pale yellowish brown labrum small, its greatest breadth being at most half that of third antennal segment. The paler labella with only a few scattered spinules below. Thorax brown and likewise abdominal tergites. Hypopygium, including anal tube, brown and as figure 13A. Legs brown, but front pair paler and apical third of hind femur typically darker. Front basitarsus as figure 13B, all five fore-tarsal segments with a posterodsorsal hair palisade and segment 5 distinctly longer than 4. Hairs below basal half of hind femur scarcely differentiated from adjacent hairs of anterior face and shorter than anteroventral hairs of apical quarter. Wing 1.3–2.1 mm long. Costal index 0.48–0.52. Costal ratios 2.20–2.61:1.37–1.50:1. Costal cilia 0.09–0.15 (usually <0.12) mm long. Vein 3 with no hair at base, or rarely with a minute hair. Axillary ridge with two or three bristles, which are slightly longer than longest costal cilia. Vein Sc not reaching R. Veins pale brown, but 7 paler still. Membrane tinged 1

brownish grey, but varying in intensity so that sometimes clearly evident to naked eye but sometimes not so.