Megaselia russellsmithi 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 : 1607-1609

Megaselia russellsmithi Disney sp. n.

( Figures 7–8 )

Male

Frons brown, clearly broader than long, with 48–64 hairs and dense but very fine microtrichia. Upper supra-antennal bristles (SAs) almost as long and robust as the lower pair. The antials about level on frons with upper SAs but a little lower than anterolaterals, and about twice as far from upper SAs as either is from an anterolateral bristle. Pre-ocellars a little further apart than either is from a mediolateral bristle, which is slightly higher on frons. Cheek with three to six bristles and jowl with three that are longer and more robust. The subglobose postpedicels are brown, without subcutaneous pit sensilla (SPS) vesicles. Palps yellow, at most a third as broad as postpedicel but 1.5 times as long as breadth of latter, with five to six bristles (the longest shorter than lower SAs but longer than those on jowl) and six to eight hairs. Labrum pale grey and about 0.9 times as wide as a postpedicel. Labella paler, the dorsolateral bands being scarcely differentiated, and with very few short spinules below. Thorax brown. Three notopleural bristles and no cleft in front of these. Mesopleuron with five to 11 (mean: 7) hairs. Scutellum with an anterior pair of hairs (subequal to those in middle of scutum) and a posterior pair of bristles. Abdominal tergites brown with small hairs, but those at rear of T6 longer. Venter grey, and with hairs on segments 3–6, but those on 3 and 4 are few and may be reduced or absent. Hypopygium mainly brown but the left lobe of hypanduum and anal tube are pale grey, and as in Figures 7A–B . Apart from brown patch on mid coxa, legs yellowish brown or paler, the hind femur being darkest with the tip darker still. Fore tarsus with posterodorsal hair palisade on segments 1–4 or 5 and 5 clearly longer than 4. Its basitarsus with one to two rows of hairs modified as short spinules. Dorsal hair palisade of mid tibia extends about 0.6 times its length. Hairs below basal half of hind femur shorter than those of anteroventral row of outer half. Hind tibia with 17–21 differentiated posterodorsal hairs and spinules of apical combs simple. Wings 1.3–1.6 mm long. Costal index 0.46–0.49. Costal ratios 2.5–3.2:1.1– 1.3:1. Costal cilia (of section 3) 0.07–0.08 mm long. Hair at base of vein 3 minute or absent. With two axillary bristles (one with three on one wing only), both being longer than costal cilia. Subcosta (Sc) not reaching R1. Thick veins and veins 4–6 pale greyish brown, vein 7 very pale grey. Membrane tinged grey (evident to naked eye when viewed against a white background). Haltere brown.

Female

Head similar to male but labrum about 1.3 times wider than diameter of postpedicel and palp about 1.3 times as long as latter’ s diameter. Otherwise head similar to male. Thorax as male. Abdominal tergites brown. T5–T7 as in Figure 8A . Venter grey, and with hairs below segments 4–6 or 5–6 only. Sternite 7 and posterolateral lobes at rear of sternum 8 as in Figure 8B . Cerci grey and as in Figure 8C . Furca not evident. Dufour’ s crop mechanism about twice as long as greatest width, rounded behind and about 0.10– 0.11 mm long. Legs similar to male but 21–23 differentiated posterodorsal on mid tibia. Wing as male except 1.7–1.8 mm long. Costal index 0.48–0.50. Costal ratios 2.6– 3.2:1.1–1.2:1. Costal cilia 0.10–0.12 mm long. Otherwise it and haltere as male.

Material

Holotype: male, England, Berkshire , Windsor Great Park, (grid ref. SU9872 ), Bear Rails, crown of old oak ( Quercus sp.) pollard, pitfall trap, 22.vi–13.vii.2012, A. R-S, ( UCMZ, 20–172) . Paratypes: two males, two females as holotype (20–172 & 173).

Etymology

Named for the collector Dr. Tony Russell-Smith.

Recognition

In the keys to the males of British species ( Disney 1989), the males run to couplets 79– 81, which are revised below.

Figures

Figure 7. Megaselia russellsmithi male, hypopygium. (A) Left face; (B) right face (minus penis complex). Scale bar: 0.1 mm.

Figure 8. Megaselia russellsmithi female, details of abdomen. (A) Tergites 5–7; (B) sternite 7 and lobes at rear of sternum 8; (C) right cercus. Scale bars: 0.1 mm.