Sergeyoxys monoceratus Davidian sp. nov.

(Figs 1–11)

Type material: Holotype: RUSSIA: ♀, Amur Province, 25 km N of Svobodnyy, Chernovka Village on Bolshaya Pera River, 31.VII–2.VIII.2003 (S. Belokobylskij) (ZISP). Paratype: RUSSIA: 1 ♀, Primorskiy Territory, Khanka District, vicinity of Novokachalinsk, western shore of Khanka Lake, 4–7.VIII.2006 (S. Belokobylskij) (ZISP).

Description. Female. Head transverse, smooth and shiny, sparse setae, wider than mesosoma at level of tegulae. Eyes large, oval, with short sparse setae in lower half. Antenna 11-segmented, weakly widened towards apex (Fig. 1). F1 and F2 3.5 × and 2.6 × longer than their median width respectively. Transverse diameter of eye (dorsal view) 1.5 × length of temple. РОL twice Оd. Tentorial index 0.3. Width of clypeus 1.6 × its height. Outer margin of mandible pubescent. Fore wing narrow, 3.0 × longer than maximum width (Fig. 5). Pterostigma 2.3 × longer than its maximum width, 1.5 × longer than metacarp, almost as long as radial vein. Parallel vein very long, almost touching distal margin of wing. Basal part of fore wing plate (until basal vein) covered by sparse and very short setae; remaining part denser and long (at least in 2.0 ×) setae. Apical margin of fore wing with longer setae. Hind wing with costal (Co+Sc) and radial (R) veins (Fig. 7).

Metasomal petiole with weak spiracular and additional lateral tubercles, 3.0 × longer than width at level of spiracles, distinctly narrowed towards apex from additional tubercles (Fig. 2). Distance from base of petiole to spiracular tubercles 2.0 × longer than distance from additional tubercles to apex of petiole. Width of petiole on level of spiracular tubercles slightly less than distance between spiracular and additional tubercles. Dorsal surface of petiole almost smooth, ventral surface irregularly areolate. Sides of petiole between spiracular and additional tubercles with two to three medium length erect setae. Ovipositor sheath very wide, subtriangular, evenly narrowed from base to apex, weakly serrate in subapical part of ventral margin (Figs. 8–10). Unpaired prong weakly upcurved, its basal part widely triangular with concave basal margin and with large median setiferous pore dorsally (Fig. 6). Dorsal surface of prong with longitudinal furrow, its apical part slightly widened, on ventral side with singly preapical short and thick spur.

Colour. Head and fifth to eleventh antennal segments brown, face, malar space, mandible (except darkened apex), mouth apparatus, and four basal segments of antenna yellow. Mesosoma brown, prothorax slightly paler. Legs yellowish, last tarsal segments dark. Fore wing darkened along basal vein, on first and second abscissae of radial vein (R1 and R2), and below nervulus and second abscissa of longitudinal anal vein; pterostigma dark in median part. Petiole pale brown, yellowish apically. Most of metasoma including ovipositor sheaths brown, second tergite entirely and middle part of third tergite yellowish, prong pale brown.

Length of body, antenna and fore wing in holotype 2.1, 1.1 and 1.3 mm, in paratype—2.7, 1.4 and 1.5 mm.

Distribution. For the time being, the species is known from the Amur Province and Primorskiy Territory, located in the Far East of Russia (Fig. 11).