Megaselia pilusdepilata Disney, 2020

Disney, R. Henry L. & Durska, Ewa, 2020, New Species And New Records Of Megaselia Rondani (Insecta: Diptera: Phoridae) From Wigry National Park (Poland), Annales Zoologici 70 (1), pp. 97-108 : 98-100

Megaselia pilusdepilata Disney , sp. nov.

( Figs 21–32)

Description. (Male). In the key to the males of the species of Megaselia recorded from the British Isles ( Disney 1989), it runs to couplets 107 and 143, for mesopleuron with hairs, or couplets 194 and 254, for mesopleuron bare. In Schmitz & Beyer’s (1965) key to Abteilung IV Zweite Reihe it runs to couplets 107 and 143. In all cases the hypopygia are different. Likewise in Borgmeier’s (1964) key to Nearctic species for Group IV it runs either to couplet 16, lead 1, but the hypopygium is different. All subsequent additions to these couplets they fail to run down.

Male. Frons as Fig. 21, with dense but very fine microtrichia. The lower supra-antennal bristle (including a socket) on the right side is absent. Cheek with 3 bristles and jowl with 2 that are longer and more robust. Postpedicels, with a few SPS vesicles ( Fig. 22), palps and proboscis as Fig. 23, the labella with only a few short spinules below ( Fig. 24). Thorax brown, with 3 notopleural bristles and no cleft in front of these, and mesopleuron with 2 hairs on the right side ( Fig. 25) but bare on the left side ( Fig. 26). Scutellum with an anterior pair of hairs and a posterior pair of bristles ( Fig. 27). Abdominal tergites brown with moderate hairs that only a little longer at the rear of T6 ( Fig. 28). Venter gray with hairs on segments 3–6. Hypopygium as Figs 29–30), the right hypandrial lobe being vestigial. Hind femora light brown and the rest of legs dusky yellow. Fore tarsus with posterodorsal hair palisade on segments 1–4 and 5 just longer than 4. Dorsal hair palisade of mid tibia extends about 0.70 times its length. Hairs below basal half of hind femur shorter than those of anteroventral row of outer half ( Fig. 31). Hind tibia with a dozen moderately differentiated posterodorsal hairs, without anterodorsals, and spinules of apical combs simple. Wings ( Fig. 32) 1.19 mm long. Costal index 0.48. Costal ratios 2.62: 1.21: 1. Costal cilia (of section 3) 0.13× mm long. Vein 3 hair 0.04× mm long. 2 unequal axillary bristles, the outermost being 0.08 mm long. Sc not reaching R1. Haltere knob pale.

Type material. Holotype male, Poland, Wigry National Park , in emergence trap in plot 5 with Impatients parviflora DC, IX. 2017, E. Durska leg. ( MIZ PAS, – 28-59).

Etymology. Named after the mesopleuron being hairy ( pilus) or bare ( depilata). Comment. The left lower SA bristle being absent and the left mesopleuron being bare suggests that the mesopleuron normally has a few hairs and that early in development a faulty switching gene deleted these hairs and the SA bristle in this specimen on the left side only.