Chersodromia tiomanensis, 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 : 42-44

Chersodromia tiomanensis sp. nov.

Figs 70-72

Diagnosis

Small species with single pair of vertical bristles; palpus pale yellow; scutum brownish yellow on prescutellar depression and anterior corners; legs almost uniformly yellow; halter pale.

Description

Male LENGTH. Wing 1.2-1.3 mm.

HEAD. Brown. 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 brownish (postpedicel somewhat paler); pedicel with circlet subequally short setae; postpedicel with lower margin convex and with short dorsoapical extension, about 2.0 times (1.7-1.8) longer than wide; stylus nearly 3.0 times longer than postpedicel and about 1.5 times longer than scape, pedicel and postpedicel combined. Gena narrow. Palpus pale yellow.

THORAX. With scutum largely brownish leaving brownish yellow spaces on prescutellar depression and on anterior corners; scutellum brownish; pleura yellow to brownish yellow. Prothoracic episterna

lacking setae above fore coxa. Postpronotal bristle long. Mesonotum with 2 notopleurals, 1 postsuturalsupra-alar, 1 postalar and 4 scutellars (inner pair very long, cruciate; outer pair very short); acrostichals short, biserial; dorsocentrals long, 3 pairs, surrounded by additional setulae.

LEGS. Almost uniformly yellow, only tarsomere 5 brownish. Coxae and trochanters with unmodified setation. Fore femur somewhat thickened. Fore tibia spindle-like, with several erect setulae. Fore and mid tarsi with erect setulae. 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) 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, 4 anterodorsal, 2-3 anteroventral bristles of different lengths on apical half. Hind tarsus unmodified.

WING. Normally developed, hyaline, covered with uniform microtrichia; veins yellowish to brownish yellow. Costal vein with short setulae along anterior margin. Costal bristle long, brownish. Costal index: 26/17/23. Vein Rs originating before middle of cell r 1 (closer to humeral crossvein), long, longer than crossvein bm-cu. R 2+3 almost straight. R 4+5 and M 1+2 slightly convergent near wing margin. A 1 absent. Crossveins bm-cu and r-m contiguous. Crossvein bm-cu oblique. Halter pale.

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

TERMINALIA. ( Figs 70-72 ) Cerci broadly separated; left cercus moderately long, branched into two tapered lobes, with several unmodified setae; right cercus moderately long, shorter than left cercus, digitiform, with several unmodified setae. Epandrium completely divided. Left epandrial lamella fused to hypandrium, with several short setae on apical part. Left surstylus with upper lobe short, digitiform, with several long unmodified setae. Right epandrial lamella subtriangular, covered with numerous unmodified setae of different lengths. Right surstylus not prominent. Hypandrium with 3 moderately long, closely set setae. Phallus somewhat elongate. Two rod-shaped apodemes present.

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

Material examined

Holotype ♂

MALAYSIA: Pulau Tioman, Monkey Bay, 14 July 2005, sandy beach, sweeping (reg. 25216, leg. P.G.; in ZRC).

Paratypes

MALAYSIA: 1 ♂, 9 ♀♀, Pulau Tioman, Monkey Bay, 14 July 2005, beach, sweeping (reg. 25216, leg. P.G.).

Etymology

The species is named after its type locality, Pulau Tioman.

Distribution

Malaysia.

Habitat and seasonal occurrence

This species is found on beaches in July.

Remarks

The new species is similar to C. singaporensis and C. malaysiana sp. nov. However, both these species have brownish palpi.

Figures

Figs 70-72. Chersodromia tiomanensis sp. nov., ♂ terminalia. 70. right epandrial lamella, lateral view. 71. epandrium and cerci, dorsal view. 72. left surstylus, lateral view.