Megaselia quadribrevis, DISNEY, 2003

DISNEY, R. H. L., 2003, Tasmanian Phoridae (Diptera) and some additional Australasian species, Journal of Natural History 37 (5), pp. 505-639 : 575-578

Megaselia quadribrevis sp. nov.

(figures 35, 36A)

Material

H  : male, Tasmania, Hobart, Sandy Bay, Acushla Court , garden, 21–22 September 1998 ( R. H. L. Disney —25-27) ( TMH).

P    : 5 males, 2 females as holotype except 16–26 September 1998 ( RHLD —25-22, 25-25, 25-29, 25-32) ( TMH, UMZC). Female, Fern Tree, Grays Road, 147°15∞E, 42°57∞S (grid ref. 203474), 540 m altitude, 7–17 August 2000 ( RHLD —25-41) ( UMZC) .

Etymology The name refers to the shortened fourth tarsal segments on the middle legs.

Diagnosis

The combination of scutellum with posterior pair of bristles and anterior pair of small hairs; bare mesopleuron; costal index>0.44; vein 3 forked; hind tibia without differentiated anterodorsal hairs; frons with dense microsetae; brown male abdominal tergites with normal hairing; and mid tarsal segment 5 being much longer than 4; takes the males of this species to couplet 46 on p. 88 of Borgmeier’s (1967b) keys. For the females the combination of a lack of any swelling of costa; normal brown abdominal tergites; yellow haltere knob; antials about midway between eye margin and upper supra-antennal bristles; costal section 1>2+3; yellow femora, but with brown tip to hind femur; and anterolateral bristles about level with upper SAs; takes them to couplets 55 or 59 on p. 89. Males differ from M. postorta Borgmeier by having more numerous hairs but no strong bristles on epandrium. Females are immediately distinguished from M. mediocris Borgmeier by the welldeveloped vein Sc, whose tip is confluent with R, and from M. boninensis Beyer by 1

the dark tip to hind femur; and from both species by the yellowish brown third antennal segments, as opposed to dark brown. No SPS vesicles in third antennal segment; palps yellow; SAs unequal; three bristles on notopleuron; front basitarsus slender; hairs below basal half of hind femur longer than those of anteroventral row of outer half.

Male

Frons brown and clearly broader than long. Anterolateral bristles about level with upper SAs, but antials slightly lower. Pre-ocellars closer together than either is from a mediolateral, and all four bristles in an almost straight transverse row. Three to five bristles on cheek and two longer ones on jowl. Five to eight bristles on palp. Orange-brown labrum only about 0.7× as wide as third antennal segment. The paler labella with scattered hairs and only a few spinules below. Thorax brown, but sometimes more orange-brown. Hairs of abdominal tergites a little stronger at sides of T 2, posterolaterally on T 3– T 5 and at rear of T 6. Venter whitish grey, with hairs below segments 3–6. Hypopygium brown, with paler brown anal tube, and as figure 36A. All five fore tarsal segments with a posterodorsal hair palisade and segment 5 a little longer than 4. Mid tibia with near-dorsal hair palisade extending almost three-quarters of length. Mid tarsal segments 3–5 as figure 35A. Hind tibia with 10–12 posterodorsals. Wing 1.6–2.3 mm long. Costal index 0.45–0.50. Costal ratios 2.7–3.2:1.5–1.8:1. Veins brown, 4–6 being darkest, and membrane clearly tinged greyish brown. With two to four (usually three) axillary bristles, which are about as strong as costal cilia. No hair at base of vein 3.

Female

Head similar to male except widths of third antennal segment and labrum subequal. Thorax similar to male. Abdominal tergites 5–7 as figure 35D. Sternite 7 well developed, being tapered to a dark point anteriorly, gradually narrowing to a rounded hind margin with well-developed hairs. Paired lobes at rear of sternum 8 as figure 35C. Pale whitish yellow epiproct and cerci as figure 35B. Internally, Dufour’s crop mechanism somewhat elongated and rounded at rear. Four rectal papillae. Legs similar to male except mid tarsal segment 5 is scarcely longer than 4 and hind tibia with 15–19 posterodorsals. Wing length 2.4–2.5 mm. Costal index 0.47–0.50. Costal ratios 3.4–3.6:1.9–2.0:1. Otherwise wing as male.