Chersodromia glandula, Grootaert & Shamshev, 2012

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 : 32-34

Chersodromia glandula sp. nov.

Figs 52-54

Diagnosis

Characterized by 2 pairs of vertical bristles; antenna yellow; palpus brownish; thorax brownish; halter pale; legs almost uniformly yellow, only tarsomeres 4 and 5 somewhat brownish; abdominal tergite 2 broadened, thickened posteriorly.

Description

Male LENGTH. Body 1.6-2.1 mm, wing 1.5-1.9 mm.

HEAD. Brownish in ground-colour, with black bristles, greyish pollinose. Frons rather broad, somewhat widened toward ocellar tubercle, in middle nearly 2.5 times as broad as anterior ocellus. Face below antennae somewhat broader than frons, widened in lower part. Eyes rather narrow. Ocellar tubercle and vertex with 2 pairs of equally long bristles. Occiput with 1 row of short postoculars and rather numerous bristles of different lengths. Gena deep, with 3-4 marginal setae. Antenna yellow; postpedicel conical, about 2.5 times longer than wide, with very small dorsoapical extension; stylus nearly 2.0 times as long as postpedicel. Palpus rather small, brownish, elongate oval, with several black setae including 1 long subapical; sensory pit absent.

THORAX. Brownish in ground-colour with sutures darker in varying extent, entirely densely greyish pollinose, with black setation; spiracles brown. Postpronotal bristle long, inclinate. Mesonotum more or less evenly covered with short hair-like setae but main bristles very prominent, including 1 presutural supra-alar, 3-4 notopleurals, 1-2 postalars and 4 scutellars (inner pair cruciate); acrostichals hardly distinguishable from scutal setation, complete, arranged in 2-3 rows on anterior part, becoming more numerous and multiserial toward scutellum, 4 prescutellars longer; dorsocentrals indistinguishable from scutal setation on anterior part, represented by 4 pairs of almost equally long bristles posteriorly, complete; 2 long setae present between mid and hind coxae.

LEGS. Almost uniformly yellow, only tarsomeres 4 and 5 somewhat brownish, mostly with black setation. Fore coxa with intermixed pale and black 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 moderately long anteroventral and 1 similar posteroventral seta subapically, with 1 short anterodorsal bristle on basal third. Fore tarsus somewhat longer than fore tibia, with tarsomeres 2-5 somewhat dilated, with unmodified setation. Mid coxa with several setae of different lengths including 1 long subapical bristle directed posteriorly. Mid femur slender, with 1 row of posteroventral, moderately long (becoming shorter toward apex of femur) bristles throughout, 1 row of shorter anteroventral bristles, 2 long, thin setae near extreme base, 1 anterior subapical bristle and some prominent setae around apex. Mid tibia with 1 row of anteroventral spinules, 1 short anterodorsal bristle on basal third and circlet of 3 subapical setae. Mid tarsus somewhat dilated, distinctly longer than mid tibia. Hind coxa with brush of several long apical setae directed posteriorly. Hind femur with 1 row of very short (2 subapicals somewhat longer) anteroventral bristles, 1 row of thin posteroventral bristles (somewhat longer in apical half of femur) and 1 anterior subapical bristle. Hind tibia with 3 long anterodorsal, 3 similar dorsal and 2 anteroventral bristles, bearing 2 shorter subapical setae. Hind tarsus slender, somewhat longer than hind tibia.

WING. Normally developed, somewhat milky white, covered with uniform microtrichia, with pale to yellowish veins. Costal vein somewhat thickened meeting with R 1, bearing ordinary setulae along anterior margin. One black, moderately long costal bristle present. R 1 meeting costa beyond middle of wing. R 4+5 and M 1+2 parallel and straight in apical part. A 1 present, very fine, fold-like. Halter pale.

ABDOMINAL SCLERITES. Mostly pale brown, tergites 1 and 2 somewhat darker, especially on middle part. Tergite 1 narrow, tergite 2 broadened, thickened posteriorly; tergites 1-7 covered with brownish tomentum, bearing dark, short setae concentrated along lateral margins. Sternites covered with brownish setulae. Intersegmental gland-like structures or squamiform setae absent.

TERMINALIA. Small, pale brown, subglobular ( Figs 52-54 ). Both cerci unbranched, bearing several long setae, lacking spines. Hypoproct sclerotised, somewhat enlarged. Epandrium completely divided. Left epandrial lamella small, fused to hypandrium, with numerous short setae on apical part. Left surstylus ( Fig. 54 ) consisting of two entirely separated sclerites; upper sclerite rather conical, elongate, with 1 long seta at apex and several other setae of different lengths; lower sclerite hardly prominent, digitiform. Right epandrial lamella very large, convex, clothed in numerous setae, with moderately large ventral lobe bearing several ordinary setae. Right surstylus subrectangular ( Fig. 52 ), rather short, with several unmodified setae. Hypandrium with several minute setulae on apical part. Phallus short, two apodemes present (not on drawing).

Female Unknown.

Material examined.

Holotype ♂

SINGAPORE: Chek Jawa, 15 December 2005, mangrove, sweeping (reg. 25452, leg. P.G.; in ZRC).

Paratypes

SINGAPORE: 1 ♂, Pulau Ubin/jetty, 15 December 2005, beach, sweeping (reg. 25451, leg. P.G.).

MALAYSIA: 4 ♂♂, Johor province, Sedili kecil, 12 October 2000, beach, sweeping (reg. 20046, leg. P.G. & N. Evenhuis).

Sequences in Genbank

♂, Chek Jawa, 15 December 2005, mangrove, sweeping (reg. 25452, leg. P. Grootaert) quoted in Lim et al. (2009) as Chersodromia sp. Si1330 has been sequenced.

Etymology

The specific name refers to the modified abdominal tergite 2.

Distribution

Malaysia, Singapore.

Habitat and seasonal occurrence

Found on beach and in mangrove, from October to December.

Remarks

This species can be readily recognised among other species of Chersodromia due to the modified abdominal tergite 2 which is broadened and thickened posteriorly. Abdominal modifications are quite common among Drapetini ( Shamshev et al. 2006; Grootaert & Shamshev 2009b) but this is the first record for Chersodromia .

Figures

Figs 52-54. Chersodromia glandula sp. nov., ♂ terminalia. 52. right surstylus, dorsal view. 53. epandrium and cerci, dorsal view. 54. left surstylus, lateral view. Scale bar = 0.1 mm.