(Figs 1 A–C)
Type material. HOLOTYPE, ♂ labeled: Russia: Taimyr Reserve, Ary-Mas field station, left bank of river Novaya, 14 m a.s.l., inundated terrace, 72.5 ˚N, 101.94 ˚E, 10–12.VII. 2010, coll. A. Barkalov (SZM). PARATYPES: Russia: 9 ♂, same data as holotype, coll. A. Barkalov; 1 ♂, Krasnoyarskij Kraj, Taimyr Peninsular left bank of river Zakharova Rassokha 72.7 ˚N, 101.05 ˚E, 11–20.VII. 2011, coll. A. Barkalov (SZM and VSU).
Diagnosis. Face narrow; postpedicel small; lower postocular setae white; fore coxa with white hairs; femora green-brown; mid tibia with 2 anterodorsal and 2 posterodorsal setae; hind femur and tibia without long setae and hairs; phallus with two lateral processes on tip.
Description. Male: Body length: 2.0– 2.2 mm, wing length: 1.9–2.3 mm. Head: Frons green with purple tinge, without pollinosity. Eyes not contiguus. Face green, with brown pollinosity, narrow, lower part several times narrower than postpedicel. Antenna (Fig. 1 B) black, postpedicel small, transversely oval with rounded tip, nearly 2 x wider than long; arista apical, with short hairs. Ratio of postpedicel length to width and arista length: 0.7 /1.0/ 3.1. Proboscis brown. Palpus brown with black hairs without silver pollinosity. Lower postocular setae white. Thorax: Metallic green, scutum with bronze tinge and fine grey pollinosity. Pleura with pollinosity denser than scutum, proepisternum with light setae. Six pairs of strong dorsocentral setae. Acrostichal setae long, arranged in two rows. Scutellum with 2 long and 2 short lateral setae. Legs: Fore coxa with white hairs, mid and hind coxae with dark hairs; fore trochanters yellowish-brown. Femora mostly greenish-brown, except narrowly yellow tips. Fore femur with long white anteroventral hairs, length approximately equal to femur width. Fore tibia and tarsus with short hairs. Ratio of fore tibia and tarsus (from 1 st to 5 th): 2.5 / 1.1 / 0.5 / 0.2 / 0.2 / 0.3. Mid and hind femora with short anteroventral hairs. Mid tibia with 2 anterodorsal and 2 posterodorsal seta. Ratio of mid tibia and tarsus (from 1 st to 5 th) 3.1 / 1.6 / 0.8 / 0.5 / 0.3 / 0.4. Hind tibia with 2 short dorsal setae and short erect anteroventral hairs. Ratio of hind tibia and tarsus: 3.3 / 1.2 / 0.8 / 0.4 / 0.3 / 0.4. Wing: Membrane hyaline with dark veins; R 4 + 5 and M 1 parallel at apex. Ratio of costal section between R 4 + 5 and M 1 to that between R 2 + 3 and R 4 + 5: 1.5 / 0.6; m-cu distinctly shorter apical part of M 3 + 4 (0.4 / 2.4). Halter and cilia on lower calypter yellow. Abdomen: Metallic green, grey pollinose laterally, covered with black hairs. Epandrium oval; surstylus in apical half bent in the shape as in Figure 1 A. Phallus with apex in the form of a trident, with pair of dorsolateral processes (Fig. 1 C). Cercus with light brown hairs. Female: Unknown.
Etymology. The species is named for the shape of phallus.
Taxonomy. In the key to Palearctic species of Chrysotus (Negrobov et al. 2000), the new species runs to Chrysotus albibarbus Loew, 1857 and can be distinguished from the latter by following characters:
1. Hind tibia and base of hind tarsus dark; vein dm-cu at most 4 x shorter than apical part of vein M 3 + 4. Palpus covered with white hairs. Surstylus not broadened on tip (Figs. 1 H, J). Phallus without processes. (Fig. 1 I)........ Chrysotus albibarbus Loew
-. Hind tibia and base of hind tarsus yellow; vein dm-cu about 6 x shorter than apical part of vein M 3 + 4. Palpus with black hairs. Apical half of surstylus broadened (Fig. 1 A). Phallus is tridental in form, with a pair of dorsolateral processes (Fig. 1 C)............................................................................... Chrysotus tricaudatus sp. nov.