Megaselia pederseni sp. n.

(Figs 105–117)

Material examined. Holotype male, DENMARK, SZ, Bimose Overdrev, 30.vi–02.vii.2013, Jan Pedersen (CUMZ-8-57) . Paratype male, same data as holotype. Description. Male. Frons as Fig. 105. Cheek with 5 bristles and jowl with two that are longer and more robust. Postpedicels, without SPS vesicles, palps and proboscis as Fig. 106. Left face of thorax as Fig. 107, with 3 notopleural bristles and no cleft in front of these; and mesopleuron with only 3–4 hairs. Scutellum with an anterior pair of hairs and a posterior pair of bristles. Abdominal tergites light brown with hairs largely restricted to hind margins and those at rear of T6 not longer than those at rear of T5. Venter gray, and with hairs on segments 3–6. Hypopygium as Figs 108–112. Legs light brown to dusky yellow.

Fore tarsus as Fig. 113, with posterodorsal hair palisade on segments 1–4 and ratios of segment lengths 2.6–2.7: 1.4: 1.1–1.2: 0.9–1.0: 1. Dorsal hair palisade of mid tibia (Fig. 114) extends 0.4–0.5 times its length. Hairs below basal half of hind femur (Fig. 115) shorter than those of anteroventral row of outer half. Hind tibia with two dozen weakly differentiated posterodorsal hairs, without anterodorsals, and spinules of apical combs simple. Wings (Figs 116–117) very pale and only 0.6–1.4 mm long. Costal index 0.0.35–0.40. Costal ratios 2.7–5.6: 1.4–1.0: 1. Costal cilia (of section 3) 0.11–0.13 mm long. No hair at base of vein 3. With 2 unequal axillary bristles, the outer being 0.10–0.13 mm long. Sc not quite reaching R1. Haltere knob gray to brown.

Recognition.. In the key of Lundbeck (1922) to Group V it runs to couplet 3, but its hypopygium differs from both species. In the key to the males of the British Isles (Disney, 1989) it runs to couplet 124, where the variation in the colour of the haltere knob means both options need to be considered. Lead 1 proceeds to couplet 127, where the very pale wing of lead 1 conflicts with the description of the left hypandrial lobe. The subsequently described M. geiri Disney runs to this couplet but its hypopygium differs, with very short hypandrial lobes in particular. Taking the second lead from couplet 124 one proceeds to couplet 143 where the pale wing fits lead 1 but the hypopygium is clearly different. M. indifferens (Lundbeck) also runs to this couplet but its hypopygium is also very different (Fig. 4 in Disney, 2011b) and its wings are tinged gray with veins 4–7 brown. In the keys of Schmitz & Delage (1974) to Abteilung V it runs to couplets 5 or 6, depending on the haltere knob colour, but the hypopygia of the species clearly differ from that of M. pederseni . The very pale wings excludes numerous species.

Etymology. Named after the collector Jan Pedersen.