Megaselia species C

DISNEY, R. H. L., 2003, Tasmanian Phoridae (Diptera) and some additional Australasian species, Journal of Natural History 37 (5), pp. 505-639 : 596-598

Megaselia species C

(figure 48)

This species appears to be only known in the female sex and is probably an undescribed species.

Material

Female, Tasmania, Lake St Clair, near Cynthia Bay , 20 September 1998 ( R. H. L. Disney —25-26) ( UMZC) .

Diagnosis

The combination of scutellum with anterior pair of minute hairs and posterior pair of bristles; bare mesopleuron; costal index 0.53; forked vein 3; no differentiated anterodorsal hairs on hind tibia; dense but fine microsetae on frons; costa not swollen; abdominal tergites 1–6 not unusual; haltere brown, but not dark; and third antennal segment yellowish brown; takes this species to couplet 66 on p. 89 of Borgmeier’s (1967b) keys. This couplet is based on an exclusively male feature. However, the female of M. palpella Beyer has an elongated abdominal tergite 6, whereas the T6 of species C is broader than long. One can thus proceed to couplet 69 (p. 90), where the costal index falls between the two options. The first, by virtue of the costal ratios being 3.05:2.20:1, takes it to couplet 70 lead 1, to M. apposita Brues. The female of the latter, however, has T6 clearly longer than broad. With the costal cilia being 0.12 mm long, the second option takes it to couplet 78 lead 1, to M. digressa Brues. This species has all four supra-antennal bristles of equal length, but those of species C are very unequal such that the lower pair are much weaker and at most only half as long as the upper SAs. Also species C is larger (wing length> 2 mm, compared with <2 mm in M. digressa ). Yellow femora (part from brown tip to hind femur); three bristles on notopleuron; yellow palps; fingerlike posterolateral lobes of abdominal sternum 8; strong Sc ending in R; and 1

cerci short.

Female

Frons brown, broader than high, and with 56–64 hairs. Antials lower on frons than upper SAs and clearly closer to anterolaterals, which are a little higher but still lower than upper SAs. Pre-ocellars almost as far apart as either is from a mediolateral, but distinctly a little lower on frons. Two bristles on cheek and two much longer ones on jowl. Yellowish brown third antennal segment lacks SPS vesicles. Five strong bristles, five weak bristles and as many hairs on palp. Brown labrum about as wide as third antennal segment. Pale dusky yellow labella with narrow yellow bands above, only a few spinules below and with strong teeth adjacent to glossa. Thorax brown. Abdominal tergites brown, with small hairs that are are only a little longer at rear of T6. T5–T7 as figure 48A. Sternite 7 as figure 48B. Venter brownish grey, with well-developed hairs below segments 3–6. Cerci pale whitish yellow and as figure 48C. Poterolateral lobes of sternum 8 as figure 48D. Internally, Dufour’s crop mechanism about 2.3× as long as broad and rounded posteriorly; with four rectal papillae, and pale brown furca (sternite 9) is subrectangular (about 1.8× as wide as long) with rounded posterolateral corners. Front tarsus slender, with posterodorsal hair palisades on all five segments, and segments 4 and 5 subequal in length. Near-dorsal hair palisade of mid tibia extends about 0.7× length. Hairs below basal half of hind femur a little longer than longest hairs of anteroventral row of outer half. About 15 differentiated posterodorsal hairs on hind tibia, but uppermost five or six fine. Wing length 2.6 mm. No hair at base of vein 3. Three axillary bristles a little longer than costal cilia. Veins brown and membrane brownish grey (evident to naked eye).