Chersodromia nigripennis, Shamshev & Grootaert, 2005

Grootaert, Patrick & Shamshev, Igor V., 2012, The fast-running flies (Diptera, Hybotidae, Tachydromiinae) of Singapore and adjacent regions, European Journal of Taxonomy 5, pp. 1-162 : 38-40

Figs 63-65

Diagnosis

Small species with 2 pairs of vertical bristles; postpedicel with distinct dorsoapical extension; palpus white, elongate; legs largely pale brown; halter with brownish yellow knob.

Description

Male LENGTH. Body 1.6 mm, wing 1.5 mm.

HEAD. Largely black in ground-colour, gena brown. Frons greyish pollinose, rather narrow, widened toward ocellar tubercle, in middle nearly 1.5 times as broad as anterior ocellus. Face almost linear, widened in lower part, narrow, in middle nearly 2.5 times narrower than frons. Ocellar tubercle and vertex with 2 pairs of long, black bristles (partly missing). Occiput greyish pollinose, broadly subshining round neck, with some scattered pale setulae longer in lower part. Gena moderately broad. Antenna brown; postpedicel with distinct dorsoapical extension, about 2.0 times longer than wide, stylus nearly 2.0 times as long as postpedicel. Palpus moderately large, white, elongate, with several inconspicuous setae including 1 longer subapical one; sensory pit present.

THORAX. Brownish in ground-colour, entirely finely greyish pollinose, with black setation. Postpronotal bristle long. Mesonotal bristles very prominent, presutural supra-alar lacking, 3 notopleurals (2 longer), 1 postalar and 4 scutellars (inner pair cruciate); acrostichals arranged in 1-2 irregular rows, short, scattered, 2 bristles on prescutellar depression longer; dorsocentrals uniserial, becoming somewhat longer toward scutellum, complete, some additional setulae present on supra-alar space; two long setae present between mid and hind coxae.

LEGS. Largely pale brown; mid and hind coxae at apex, fore and mid femora at apex, fore and mid tibiae at extreme base and all tarsi paler. Fore coxa with intermixed pale and dark setae of different lengths, latter longer nearer to outer margin of coxa. Fore femur somewhat thickened, with 1 row of short anteroventral and 1 row of similar posteroventral bristles, bearing 1 longer anterior subapical bristle and some setae around tip. Fore tibia spindle-like, bearing 1 long anteroventral and 1 similar posteroventral bristle on subapical part, with some erect dorsal setulae. Fore tarsus nearly as long as fore tibia, with tarsomeres 2-5 somewhat dilated, clothed mostly in unmodified setulae, tarsomere 1 with some ventral spinule-like setulae. Mid and hind coxae with unmodified setation. Mid femur slender, with hardly prominent rows of anteroventral and posteroventral bristles throughout, bearing 2 long, yellow, thin setae near extreme base, 1 anterior subapical bristle and some prominent setae round apex. Mid tibia with 1 row of anteroventral spinules, 2 anterodorsal bristles and circlet of 3 subapical setae. Mid tarsus distinctly longer than mid tibia, with tarsomeres 2-5 somewhat dilated, clothed mostly in unmodified setulae, tarsomere 1 with some ventral spinule-like setulae. Hind femur with 1 row of very short (2 subapicals somewhat longer) anteroventral bristles, 1 row of thin posteroventral bristles (somewhat longer on apical half of femur), some prominent posterodorsal bristles, 3 erect dorsal bristles near extreme base and 1 anterior subapical bristle. Hind tibia somewhat sinuate, narrowed basally, with 3 anteroventral, 2 anterodorsal, 3 dorsal (concentrated in apical part of tibia) and 2 subapical bristles. Hind tarsus slender, somewhat longer than hind tibia, with unmodified setulae.

WING. Normally developed, deeply infuscate, covered with uniform microtrichia. Costal vein with moderately long setulae along anterior margin. One long costal bristle present. R 1 meeting costa at middle of wing. R 4+5 and M 1+2 parallel and straight on apical part. A 1 present, very fine, fold-like. Halter with brownish yellow knob and pale stem.

ABDOMEN. Unmodified, mostly pale brown and with scattered dark setulae, pregenital segments darker and with longer bristles. Intersegmental gland-like structures or squamiform setae absent.

TERMINALIA. Moderately large, brown ( Figs 63-65 ). Both cerci unbranched, bearing several long setae, lacking spines, elongate, of subequal length. Epandrium completely divided. Left epandrial lamella small, fused to hypandrium, with numerous short setae on subapical part. Left surstylus consisting of two entirely separated sclerites; upper sclerite rather subrectangular with narrowed apical part, bearing several setae of different lengths; lower sclerite long, digitiform in apical half, with additional process bearing several short setae. Right epandrial lamella large, convex, clothed in numerous setae, with moderately large ventral lobe bearing several unmodified setae. Right surstylus rather digitiform, short, with several unmodified long setae. Hypandrium with 4 setae of different lengths on subapical part. Phallus short; two apodemes present (not on drawing).

Female Unknown.

Material examined

Holotype ♂

MALAYSIA: Johor province, Sedili kecil, 12 October 2000, beach, sweeping (reg. 20046, leg. P.G. & N. Evenhuis; in ZRC).

Etymology

The specific name 'pasir' means 'sand' in Malay and Indonesian.

Distribution

Malaysia.

Seasonal occurrence and habitat. This species is found on beaches in October.

Remarks

This species is similar to C. nigripennis differing primarily from the latter by the elongate white palpi and paired left surstylus.

Figures

Figs 63-65. Chersodromia pasir sp. nov., ♂ terminalia. 63. right surstylus, dorsal view. 64. epandrium and cerci, dorsal view. 65. left surstylus, lateral view. Scale bar = 0.1 mm.