Megaselia dewittensis, DISNEY, 2003

DISNEY, R. H. L., 2003, Tasmanian Phoridae (Diptera) and some additional Australasian species, Journal of Natural History 37 (5), pp. 505-639 : 541-543

Megaselia dewittensis sp. nov.

(figure 16)

Material

H  : male, Tasmania, Hobart, Battery Point, De Witt Street , garden, 10–12 June 1995 ( R. H. L. Disney —25-21) ( TMH).

Etymology The name refers to the type locality, De Witt Street.

Diagnosis

The combination of scutellum with a pair of minute hairs and a pair of bristles; mesopleuron with>20 fine hairs plus a long bristle; costal index about 0.5; costal cilia <0.1 mm long; with differentiated anterodorsals on the hind tibia; yellow haltere knob; and costal section 1<sections 2+3; will take this species to couplet 25 on p. 203 of Borgmeier’s (1967a) keys. One cannot then proceed as this couplet is based on exclusively female characters, despite M. vittata Borgmeier being only known in the male sex. However, it and the remaining three species, which are only known in the female sex, are all distinguished from M. dewittensis by their yellower third antennal segments, thorax and legs as well as their subequal supra-antennal bristles. In M. dewittensis the lower SAs are <0.6× as long as the upper pair. The subsequently described M. araneivora Gotô also runs to these couplets. It is also a yellower species and the left face of the epandrium has fewer (<15) hairs than the new species. Labella enlarged and densely spinose below.

Male

Frons brown, only a little wider than long and with dense but very fine microsetae. Anterolateral bristles clearly higher on frons than antials, which are about level with upper SAs and equidistant between the latter and ALs. Lower SAs not only shorter but clearly finer than upper pair. Pre-ocellars closer together than either is from a mediolateral and all four bristles in an almost straight transverse row. Three bristles on cheek and two stronger ones on jowl. Third antennal segment light brown. Its greatest diameter at most 0.4× that of labium. Palp yellow with six robust bristles, the most distal five being subequal and only about 1.25× as long as greatest width of palp, which is only about two-thirds that of third antennal segment. Labrum light brown and its breadth less than that of palp. Labella with a brown band each side above. Three bristles on notopleuron. Abdominal tergites brown with small hairs, apart from two strong posterolaterals each side of T 2 and the differentiated hairs at rear of T 6 (figure 16B). Venter brown with hairs below on segments 3–6. Hypopygium brown, with paler anal tube, and as figure 16B. Only left lobe of hypandrium is well developed. Legs brown, the hind pair being darkest and the front pair more yellowish. Front basitarsus slender, only segments 1–4 with a posterodorsal hair palisade; and segment 5 distinctly longer than 4. Near-dorsal hair palisade of mid tibia extends about 0.8× its length. Hairs below basal half of hind femur clearly longer than those of anteroventral row of outer half. Hind tibia with five to seven differentiated anterodorsal hairs and about nine posterodorsals (figure 16A). Wing length 1.9–2.0 mm. Costal ratios 2.65:1.83:1. Costal cilia 0.08–0.09 mm long. Vein Sc obscure and ending well before R. With two axillary 1

bristles, the outermost being longer than costal cilia. Vein 3 with a fine hair at base. A slight swelling in middle of costal section 1. Veins light brown, the costa being paler. Membrane lightly tinged brown.