Megaselia velutinicavus Disney, 2014

Disney, R. H. L. & Russell-Smith, A., 2014, Additions to the British list of Megaselia Rondani (Diptera: Phoridae), including two new species, from the crowns of ancient pollarded trees, Journal of Natural History 49 (25), pp. 1599-1626 : 1615-1618

Megaselia velutinicavus Disney , sp. n.

( Figures 22A–D )

Male

Frons brown, clearly broader than long, with 60–62 hairs and dense but very fine microtrichia. SAs almost equal. The antials lower on frons than the anterolaterals but higher than the upper SAs, and about 2.5 times as far from the upper SAs as either is from an anterolateral bristle. Pre-ocellars a little farther apart than either is from a mediolateral bristle, which is a little higher on frons. Cheek with five bristles and jowl with two. The subglobose postpedicels brown and without SPS vesicles. Palps dusky yellow, at most a third as broad as postpedicel but about 1.3 times as long as breadth of latter, with four bristles and five hairs. Labrum pale yellowish grey and about half as wide as a postpedicel. Labella with combined width 1.5–1.6 times as broad as a postpedicel, paler than palps and the dorsolateral bands are only weakly pigmented, and with only six to eight short spinules at tip. Thorax brown. Three notopleural bristles and no cleft in front of these. Mesopleuron with six hairs. Scutellum with an anterior pair of hairs (about as strong as those in the middle of the scutum) and a posterior pair of bristles. Abdominal tergites brown with hairs longest at hind margins, especially on T6. Venter grey, and with hairs on segments 3–6. Hypopygium brown, with a grey anal tube, and as in Figures 22A and 22B . Legs brown. Fore tarsus with posterodorsal hair palisade on segments 1–4, and 5 about as long as but broader than 4. Dorsal hair palisade of mid tibia extends almost half its length. Hairs below basal half of hind femur shorter than those of anteroventral row of outer half. Hind tibia with 24–26 differentiated posterodorsal hairs and spinules of apical combs simple. Hind basitarsus with an elongated, internal hairy cavity ( Figures 22C–D ). Wings 1.7 mm long. Costal index 0.40. Costal ratios 3.7:1.0:1. Costal cilia (of section 3) 0.17–0.18 mm long. No hair at base of vein 3. With unequal axillary bristles, the outer being shorter than costal cilia. Sc not reaching R1. Thick veins light brown, thin veins 4–6 a little darker and 7 pale. Membrane tinged grey (evident to naked eye when viewed against a white background). Haltere brown.

Holotype: male, England, Essex, Hainault Forest , (grid ref. TQ4894 ), crown of hornbeam ( Carpinus betulus ), 22.v–11.vi.2012, A. R-S, ( UCMZ, 20–176).

Etymology

The name refers to the hair-lined cavity of the hind basitarsus.

Recognition

In the keys to British species ( Disney 1989) the males run to couplets 130 and 131. This M. pusilla (Meigen) species complex has since been added to (Disney 2011). M. velutinicavus is immediately distinguished from the rest of this complex by the internal hairy cavity of the hind basitarsus ( Figure 22D ), apart from the hypopygium ( Figures 22A–B ).

Figures

Figure 22. Megaselia veluitinicavus male. (A) Left face of hypopygium; (B) tips of right paraphysis and posteroventral region of epandrium; (C) anterior face of hind basitarsus; (D) the internal hairy cavity of the hind basitarsus (anterior focal plane). Scale bars: 0.1 mm.