Megaselia brevivallorum, DISNEY, 2003

DISNEY, R. H. L., 2003, Tasmanian Phoridae (Diptera) and some additional Australasian species, Journal of Natural History 37 (5), pp. 505-639 : 535-536

Megaselia brevivallorum sp. nov.

(figure 12C)

Material

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

Etymology The name refers to the relatively short dorsal hair palisade of the mid tibia.

Diagnosis

The combination of scutellum with a pair of small hairs and a pair of bristles; mesopleuron with six to eight short hairs and no bristles; costal index <0.4; and costal section 1> sections 2+3, will take this species to couplet 2 on p. 206 of Borgmeier’s (1967a) keys, as may some specimens of M. bilobulus (see above); but these two species are readily distinguished in the key below. M. brevivallorum , like M. turbidipennis Borgmeier , differs from M. arctifurca Borgmeier by the much shorter anal tube, the cerci being <1.5× as long as broad. It differs from M. turbidipennis in having near-dorsal hair palisade of the mid tibia reaching only just beyond mid-point, as opposed to being at least two-thirds of length. Furthermore, its haltere knob is brown, not dirty yellow, but its palps are paler (yellowish brown) than those of M. turbidipennis . The costal index of latter is>0.4. Third antennal segment with numerous SPS vesicles, whose diameters are subequal to those of sockets of lower supra-antennal bristles; notopleuron with three bristles; hairs at rear of abdominal tergite 6 subequal to those on left side of epandrium; only left lobe of hypandrium well developed; all femora brown; basitarsus of front leg slender and lacking modified hairs below; hairs below basal half of hind femur differentiated and longer than those of anteroventral row of outer half; hind tibia with about 15 differentiated, but not strong, posterodorsal hairs and no differentiated anterodorsals.

Male

Frons broader than long, brown and with dense, but fine, microsetae. Lower SA bristles robust, but a little shorter and weaker than upper SAs. Antials about level with upper SAs but clearly closer to anterolaterals, which are slightly higher on frons. Pre-ocellars a little further apart than either is from a mediolateral, all four bristles being in an almost straight transverse row. Three bristles on cheek and three longer ones on jowl. Third antennal segment pale brown. Palps more yellowish brown, with three strong bristles and four weaker ones. Labrum pale yellowish brown and only about two-thirds as wide as maximum diameter of third antennal segment. Thorax and abdominal tergites brown and latter with minute hairs that are only a little differentiated at rear of T 6 (figure 12C). Venter brownish grey with only a few small hairs below segments 3–6 and 1–2 on flanks of 6. Hypopygium light brown, with anal tube and left lobe of hypandrium paler, and as figure 12C. Tibiae brown, but front pair paler, and tarsi and apical third of front coxae even paler. Front tarsus with a posterdorsal hair palisade on segments 1–4 only, and segment 5 a little longer than 4. Wing 1.13 mm long. Costal index 0.35–0.36. Costal ratios 5.19:1.80:1. Costal cilia 0.06–0.07 mm long. Two bristles on axillary ridge, the outermost being longer than costal cilia. Vein Sc clearly not reaching R. Veins

1 brown, 4–6 being darker than rest. Membrane distinctly tinged greyish brown.