Megaselia nigellifrons Borgmeier, 1967

DISNEY, R. H. L., 2003, Tasmanian Phoridae (Diptera) and some additional Australasian species, Journal of Natural History 37 (5), pp. 505-639 : 569-571

Megaselia nigellifrons Borgmeier, 1967

(figures 30, 31)

Megaselia nigellifrons Borgmeier, 1967a: 214 .

This species was described from three females from New South Wales. It is now reported from Tasmania and Western Australia, and the hitherto unknown male is described below. The species is more variable than Borgmeier supposed. It not only runs down in his keys to couplet 10 of group I (p. 200), but also to couplet 20 (p. 201). Some specimens run to couplets 41 (p. 204) and 54 (p. 205) of group II. Many , especially males, run to couplets 10–15 (p. 206) of group IV .

Material

Ten males, 19 females, Tasmania, Hobart, Battery Point, De Witt Street, garden, 1–11 January 1992 ( R. H. L. Disney —25-4-7, 25-34, 25-39); 1 male, 2 females, Mount Field National Park, Russell Falls, 26 December 1991 and 11 January 1992 ( RHLD —25-5, 25-9; 1 male, 3 females, Hobart , Sandy Bay , Acushla Court , garden, 17–23 September 1998 ( RHLD —25-25, 25-27, 25-29). Male , New South Wales, Berowra , 7–9 June 1995 ( RHLD —25-20). Male , Western Australia, 33°20∞S, 116°36∞E, 10–12 October 1996 ( Cindy Brown , 25-11) .

Male

Similar to female. Third antennal segment with numerous SPS vesicles, whose diameters are at most equal to sockets of lower SA bristles. Palp as figure 30A. Yellowish brown labrum with breadth only about 0.6× that of third antennal segment. Labella pale brownish yellow above and with only a few spinules below. Thorax as female, except anterior scutellars sometimes a little shorter than hairs at rear of scutum. With 5–24 (mean 15) hairs on mesopleuron which tend to be longer and more robust at rear margin, such that in some specimens one to three might be regarded as differentiated bristles. Three bristles on notopleuron. Abdominal tergites brown, but T 4– T 6 are variably more yellowish. Hypopygium brown, with paler anal tube (especially distal half of proctiger) and as figure 30B. Right lobe of epandrium abbreviated. Pair of small bristles on dorsal (inside) face of hypandrium strongly developed. Only fore-tarsal segments 1–4 with posterodorsal hair palisade. Mid tibia with near-dorsal hair palisade extending about 0.9× its length. Hairs below basal half of hind femur clearly longer and more robust than those of anteroventral row of distal half. Otherwise legs similar to female. Wing length 1.5–2.3 mm. Costal index 0.47–0.52. Costal ratios 3.0–3.5:2.4–2.7:1. Costal cilia 0.08–0.10 mm long. Axillary ridge with two or three bristles. One to three (usually one) hairs at base of vein 3. Otherwise wing as female. Haltere knob ranges from yellowish brown to brownish yellow.

Female

I add the following to Borgmeier’s description. Labrum orange-brown and about 1.1× width of third antennal segment, which has SPS vesicles as male. Labella pale and with only a few scattered spinules below. Notopleuron with three bristles. Anterior scutellars sometimes reduced to short fine hairs. Abdominal tergites 4–6 as figure 31. Posterolateral lobes of sternum 8 broader than long, with five or six bristles, of which the three submarginals are long, and conspicuous pubescence that overreaches hind margin. Internally, Dufour’s crop mechanism up to 0.7× as wide as long, with posterior margin a little truncated and variably a little concave in middle; with four rectal papillae and no sclerotized furca evident. Wings 1.6–2.9 mm long. Costal index 0.50–0.58. Costal ratios 2.7–3.9:2.6–3.7:1. Costal cilia 0.08–0.11 mm long. Axillary ridge with three to five (usually three) bristles. Vein 3 with one to three (usually one or three) fine hairs at base. Haltere as male.

Natural history

Mature eggs of gravid females measure 0.6× 0.2 mm. The numbers recorded per female were 2, 4, 10, 14, 16, 18 and 22.