Chersodromia isabellae, Grootaert, Patrick & Shamshev, Igor, 2010

Grootaert, Patrick & Shamshev, Igor, 2010, A new Chersodromia Walker (Diptera: Hybotidae) from shore of the Sea of Azov (Russia), Zootaxa 2645, pp. 64-68 : 64-66

Chersodromia isabellae sp. nov.

Figs. 1–6 .

Type material. Holotype male: Russia, Sennoy, Taman region [ RUSSIA: Krasnodar Territory, Temryuk District, Sennoy village, 45°18'N 36°59'E], 30 June 2010 (in alcohol; leg. I. Van de Velde). The holotype is deposited at RBINS.

Paratypes. 4 females, same data as holotype (deposited in RBINS and St. Petersburg); 1 female extracted for DNA, cuticle preserved.

Diagnosis. A small species of the C. speculifera group sensu Chvála (1978) with two pairs of long black vertical bristles. Postpedicel rounded with a dorsoapical stylus. Legs largely yellowish, but may be darkened. Fore leg with tarsomeres 2–5 contrastingly black. Wing long, rather milky white with pale veins in male, more distinct veins in female. Left surstylus with several long bristles.

Description. Male: Body length: 1.8 mm; wing: 1.4 mm. Head. Black in ground-colour. Frons wide, in front nearly as wide as pedicel, parallel-sided above antennae but widening slightly towards ocellar triangle. Face above wider than front of frons, strongly widening below, dusted. Gena below eye much wider than postpedicel, at most one fifth of height of eye. Ocellar and vertical bristles black. One pair of anterior ocellars, as long as postpedicel, crossing; 1 pair of equally long median ocellars diverging; 1 pair of minute posterior ocellars. Two pairs of verticals: inner pair longest, erect and crossing; outer pair somewhat shorter than inner pair and diverging. Postocular pubescence black, short bristly on occiput, shorter and finer below. Antenna yellowish brown, with orange tinged pedicel and brown postpedicel; pedicel with circlet of short black bristles, except 2 ventral bristles nearly as long as pedicel is wide; postpedicel almost round with long apical extension and dorsoapical stylus, 3 times as long as postpedicel, basal part of stylus only slightly thickened. Proboscis yellowish brown. Palpus yellowish, as long as 3 basal antennal segments combined, with black pubescence and stronger apical bristle nearly as long as palpus.

Thorax brownish black in ground-colour, covered with black bristles and some hair-like setae. Postpronotal lobe with 1 strong bristle. Mesonotum with 1 long erect presutural supra-alar, 2 notopleurals, 1 postsutural supra-alar, 1 long postalar; acrostichals biseriate, half as long as dorsocentrals, extending to base of scutellum; 4 equally long dorsocentrals among shorter hair-like setae; 1 pair of very long, crossing apical scutellars with short hair-like seta at each side.

Wing very pale, somewhat milky white, with indistinct veins except for R1. Veins R4+5 and M1+2 slightly divergent basally but parallel when meeting costa. Upper basal cell (br) as long as lower basal cell (bm). Hairlike setulae on anterior part of costa black, otherwise pale. One long black costal bristle present. Squama white with indistinct white ciliation. Halter completely white, with short black dorsal setula at base of knob.

Legs almost uniformly yellow, but mid and hind coxae slightly brownish tinged and some tarsomeres black (see below). Fore coxa with long black hair-like setae. Fore femur swollen on basal two-thirds; ventrally with row of short black bristles about one quarter as long as femur is wide; 1 strong black anterior preapical. Fore tibia much shorter than fore femur; with 1 black dorsal bristle on basal third. Fore tarsus longer than tibia: tarsomere 1 long, almost white with indistinct brownish ring at tip; tarsomeres 2–5 contrastingly black; tarsomere 5 widened. Mid femur more slender than fore femur; ventrally with row of black bristles; anterior preapical as long as femur is wide; row of strong anteroventrals in apical third. Mid tibia also much shorter than mid femur; with row of strong spine-like bristles becoming longer near tip and ending in one long apical that is much longer than tibia is wide. Base of mid tarsomere 1 very pale; following tarsomeres brown, tarsomere 5 black. Hind femur longest and as wide as mid femur; with 1 long preapical anterior and 1 long but fine preapical anteroventral. Hind tibia as long as femur, set with very long black bristles: 2 anteroventrals, 3 anteriors, 4 anterodorsals, 3 longer dorsals, 1 short stout ventral apical. Hind tarsomere 1 with pale spinulose ventrals and 2 strong black dorsals, twice as long as tarsomere is wide; only tarsomere 5 brown, other tarsomeres pale.

Abdomen with tergites all equally long and covered with black hair-like setae laterally, bare medially. Tergite 1 narrow; tergite 2 with basal excavation at each side. Sternite 1 very small; all sternites set with short black bristles. Genitalia ( Figs. 2–6 ) with large black pyriform hypandrium (not illustrated). Right epandrial lamella with short lateral appendage. Left epandrial lamella with several short setae apically. Cerci of subequal length, pointed (viewed dorsally), with several moderately long, unmodified setae. Left surstylus as in Figure 6 , slender, with several long, unmodified setae.

Female: Body 1.8–2.2 mm; wing 1.4–1.7 mm. Almost identical to male. Legs more yellowish brown, but variable. Colour of tarsomeres identical to male i.e., fore tarsus with tarsomeres 2–5 black; but mid and hind tarsomeres 2– 5 may be brown. Wing membrane also pale, but veins more distinct. Mid tibia without ventral spinules, apically with 1 pair of long bristles. Abdomen with segment 8 long; cercus quite wide, short, brown.

Etymology. The name “ isabellae ” is chosen firstly to thank the collector Dr. Isabella Van de Velde, but also in honour of the very pleasant Isabella wine typical of the Caucasus lowland.

Distribution and habitat. Russia (Krasnodar Territory). The new species was collected under quite typical conditions for many species of Chersodromia on a small sandy beach surrounded by different kinds of coastal vegetation.

Figures

FIGURES 1 – 6. Chersodromia isabellae sp. nov., holotype male: 1. antenna; 2. right epandrial lamella; 3. right epandrial lamella dorsally; 4. epandrium with cerci; 5. left cercus; 6. left surstylus.