Chersodromia malaysiana

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: 34-36

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scientific name

Chersodromia malaysiana

sp. nov.

Chersodromia malaysiana  sp. nov.

Figs 55-57View Figs 55-57


Small species with one pair of vertical bristles; palpus and proboscis brown; thorax brown; halter with brownish knob; legs brownish yellow.


Male LENGTH. Wing 1.2-1.3 mm.

HEAD. Black. Occiput subshining, finely pollinose. Two long, cruciate vertical bristles present. Frons subshining, slightly broadened toward ocellar tubercle. Anterior and posterior ocellars equally long, former proclinate and cruciate, latter lateroclinate. Antenna brown; pedicel with circlet of subequally short setae; postpedicel globular, with long dorsoapical projection; stylus nearly 2.0 times longer than scape, pedicel and postpedicel combined. Gena narrow. Palpus and proboscis brown.

THORAX. Brown. Prothoracic episterna lacking setae above fore coxa. Postpronotal bristle long. Mesonotum with 2 notopleural, 1 postsutural supra-alar, 1 postalar and 4 scutellar bristles (inner pair very long, cruciate; outer pair very short); acrostichals short, biserial; dorsocentrals long, 3 pairs, surrounded by additional setulae.

LEGS. Brownish yellow, mid and hind femora somewhat darker. Coxae and trochanters with unmodified setation. Fore femur somewhat thickened. Fore tibia spindle-like, with several erect setulae. Fore basitarsus with long posteroventral bristle on about middle. Mid femur with row of posteroventral spinule-like setae becoming longer toward base and with 1 anterior subapical bristle. Mid tibia with row of black ventral spinules (1 subapical longer) on apical half and some fine dorsal and anterodorsal setae. Hind femur with 1-2 longer anteroventral subapical and 1 anterior subapical bristles. Hind tibia with short but pointed apical projection; bearing 4 dorsal, 2 anterodorsal and 2 anteroventral bristles of different lengths on apical half. Hind tarsus unmodified.

WING. Normally developed, finely brownish infuscate, covered with uniform microtrichia. Costal vein with short setulae along anterior margin. Costal bristle long, brownish. Costal index: 29/15/25. Vein Rs originating before middle of cell r 1 (closer to humeral crossvein), long, longer than crossvein bm-cu. R 1 thickened near costa. R 2+3 evenly bowed toward costa, almost straight. R 4+5 and M 1+2 parallel on apical part. Vein A 1 absent. Crossveins bm-cu and r-m contiguous. Crossvein bm-cu oblique. Halter with pale stem and brownish knob.

ABDOMEN. With tergites weakly sclerotised, unmodified, brownish; with scattered unmodified setulae, tergite 7 with longer posteromarginal setae. Gland-like structures absent.

TERMINALIA. ( Figs 55-57View Figs 55-57). Cerci broadly separated, short, left cercus somewhat longer than right one, with unmodified setae. Epandrium completely divided. Left epandrial lamella fused to hypandrium, with several short setae on apical part. Left surstylus ( Fig. 57View Figs 55-57) with upper lobe subglobular in upper part, with minute marginal setulae. Right epandrial lamella subtriangular, with short slender process near apex ( Fig. 55View Figs 55-57); covered with numerous unmodified setae of different lengths, bearing 2 rather short spine-like setae on upper margin. Right surstylus not prominent. Hypandrium with several long setae on upper part. Phallus short. Two rod-shaped apodemes present.

Female Mid tibia lacking ventral spinules. Cercus elongate oval, brownish. Otherwise as in male.

Material examined

Holotype ♂

SINGAPORE: Chek Jawa, 22 December 2005, mangrove, Mal 1 (reg. 25455, leg. P.G.; in ZRC).


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

MALAYSIA: 1 ♂, Pulau Tioman, Monkey Bay, 14 July 2005, beach, sweeping (reg. 25216, leg. P.G.).


The specific name refers to the Malaysian Peninsula.

Distribution and seasonal occurrence

Malaysia, Singapore.

Habitat and seasonal occurrence

Found on beaches and mangroves from July and December.


This species belongs to the C. cursitans  group sensu Chvála (1977). In having a single pair of vertical bristles the new species could be compared with C. singaporensis  and C. tiomanensis  sp. nov. However, C. tiomanensis  sp. nov. can be readily distinguished from C. malaysiana  sp. nov. by its pale yellow palpus. Chersodromia singaporensis  has entirely pale halters.