Chersodromia gamoviensis, Maeda, Takuya, 2011

Maeda, Takuya, 2011, New species of Chersodromia from the Russian Far East (Diptera: Empidoidea: Hybotidae: Tachydromiinae), Zootaxa 2979, pp. 1-24 : 3-8

Chersodromia gamoviensis sp. nov.

( Figs. 6, 13, 20–26)

Diagnosis. A small, brownish species measuring ca. 1.5 mm. Stylus long. Face wider than frons. Wings normally developed. Male terminalia: right surstylus reduced to small projection; right epandrial lamella conspicuously large; right cercus very small; left surstylus with simple, slender outermost lobe. Setae on head and thorax black. Vertical setae (2 pairs) present; posthumeral setae absent.

Description. Holotype, male ( Fig. 6). Body length 1.55 mm; head width 0.33 mm; wing length 1.51 mm. Head ( Fig. 20) dark brown in ground-colour and greyish pollinose; palpus brown in ground-colour and greyish pollinose; proboscis brown, slightly shining; antenna brown; all setae and setulae on head black. Frons moderate in width; in frontal view face below antennal sockets wider than frons. Ocellar setae (2 pairs) moderate in length, as long as scape, pedicel and postpedicel combined. Vertical setae (2 pairs) longer than ocellar setae. In frontal view gena moderate in width, 1 / 5 as wide as maximum eye height. Occiput with setulae. Antenna ( Fig. 21): postpedicel round and slightly higher than pedicel in lateral view, with setulae along anterior margin; extension of postpedicel present dorsoapically; stylus long. Palpus with long setulae.

Thorax ( Fig. 22) dark brown in ground-colour and greyish pollinose; all setae and setulae on thorax black. Vestiture on thorax: 1 setula on each proepisternum; 1 pair of postpronotal setae; no posthumeral setae; 3 pairs of notopleural setae; 1 pair of supra-alar setae; 1 pair of long, inflected postalar setae; 3 pairs of dorsocentral setae near median line (1 long pair near scutellum); some dorsocentral setulae in multiple rows; 1 pair of incomplete rows of acrostichal setulae; 1 pair of long, inflected apically scutellar setae; 1 pair of subapical scutellar setulae.

Wing ( Fig. 13) normally developed, clear, with pale brown veins. Basicosta with 2 black setae and some setulae; costa with many dark brown setulae along anterior margin, ending at connection with vein M 1 + 2; subcosta absent; R 1 meeting costa at midway of wing; radial sector moderate in length; CuA 1 indistinctly connected to wing margin; anal vein reduced to pale, fold-like line. Calypter pale brown, minute. Halter pale brown, large.

Legs brown, stout. All setae on legs black; setulae on legs brown to pale brown. Fore femur sparsely covered with setulae (setulae of anteroventral row long), with 1 anterior preapical seta, 1 anteroventral preapical seta, 1 posterior preapical seta and 1 posteroventral preapical seta. Fore tibia somewhat swollen in dorsal view, covered with setulae (especially dense on anterior surface), with 1 anteroventral preapical seta and 1 posteroventral preapical seta. Fore tibial gland indistinct. Mid femur sparsely covered with setulae, with 1 strong anterior preapical seta and 1 anteroventral preapical seta. Mid tibia covered with setulae, with anteroventral row of some small, black spinulae (preapical one long), 1 anterior preapical seta and 1 posteroventral preapical seta. Hind femur covered with setulae, with anteroventral row of ca. 10 setae, 1 anterior preapical seta and 1 posteroventral preapical seta. Hind tibia covered with setulae (especially dense in apical part of posteroventral surface), with 2 anteroventral setae, 1 anterior seta, 1 anterior preapical seta, 1 anterodorsal seta, 1 anterodorsal preapical seta and 1 dorsal seta. Fore, mid and hind tarsomeres covered with setulae.

Preabdomen sparsely covered with pale brown setulae; tergites and sternites brown in ground-colour and sparsely greyish pollinose.

Terminalia ( Figs. 23–26). Right surstylus reduced to small projection ( Figs. 23, 25), boundary line between it and right epandrial lamella obscure. Right epandrial lamella conspicuously large (see Fig. 6), with short setae ( Figs. 23, 25). Left surstylus composed of several lobes; outermost lobe simple, slender ( Fig. 24). Left cercus moderate in size, somewhat slender, with some setulae; right cercus very small, bearing some small setulae ( Fig. 26).

Female. Unknown.

Type material. HOLOTYPE 3, labelled: Russian Far East, S. Primorye, Gamov Pen., Astaf’ev Bay (bare sands), 26.viii. 2010, leg. T. Maeda ( IBSS). Paratype: 1 3, Gamov Pen., Vityaz’ Bay, 23.viii. 2010 ( NIAES).

Etymology. This species is named after the type locality, Gamov Peninsula.

Distribution. Russian Far East: southern part of Primorsk Territory.

Remarks. This species was found only on the shores facing the open sea. Chersodromia gamoviensis is a rarely collected species (only two males were collected in this survey) and very similar to C. leleji except in male terminalia. The terminalia of C. gamoviensis differs from C. leleji mainly in the size of the right epandrial lamella and the shape of the left surstylus. The right epandrial lamella is very large, and the outermost lobe of the left surstylus is slender in C. gamoviensis .