Stilpon nigripennis, 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 : 136-138

Stilpon nigripennis sp. nov.

Figs 225-228

Diagnosis

Species with black thorax; palpus brown; wing lacking vein R 2+3.

Description

Male LENGTH. Wing 1.3 mm.

HEAD. black. Occiput subshining, finely greyish pollinose. Two moderately long, black vertical bristles. Frons linear with sides nearly parallel, rather broad, entirely tomentose, subshiney. Ocellar tubercle with minute setulae. Antenna with scape and pedicel brown, postpedicel somewhat paler. Palpus brown, with moderately long, black subapical seta.

THORAX. Black in ground-colour. Scutum entirely tomentose. Postpronotal bristle long, inclinate. Dorsocentral bristles in multiple rows, complete posteriorly. Acrostichal bristles 2-serial, complete posteriorly.

LEGS. With fore and mid tibiae and tarsi (less distinct on mid leg), hind femur (except extreme base) and hind tarsomere 5 brownish, otherwise legs yellow. Hind trochanter lacking spinules. Fore femur markedly thickened, with rows of moderately long antero- and posteroventral bristles. Fore tibia spindlelike, with ordinary setation. Mid femur slender, with 1 ventral bristle (as long as femur is deep) on about middle, 2 similar bristles closer to base and 1 long, subapical bristle anteriorly. Mid tibia with slightly prominent ventral spinules, lacking prominent bristles. Hind femur (viewed laterally) evenly thickened towards middle, with 1 row of anteroventral bristles (2-3 subapicals longer) and some dorsal erect bristles near base. Hind tibia with unmodified posterior apical comb, clothed in ordinary setulae. Fore and mid tarsi slender, hind tarsomere 1 thickened.

WING. Normally developed, covered with uniform microtrichia, uniformly brown infuscate. Costal vein with moderately long setulae along anterior margin. R 2+3 absent. R 4+5 and M 1+2 slightly bowed, divergent before wing apex. Halter with brownish yellow stem and black knob.

ABDOMEN. Mostly with light brown tergites and sternites, with inconspicuous setation; segment 8 dark brown. Gland-like structures present between tergites 3-7 ( Fig. 228 ).

TERMINALIA. Brown ( Figs 225-227 ). Cerci broadly fused, with several long setae; left cercus digitiform, slender, bearing conidia-like apical sensilla. Epandrium completely divided. Left epandrial lamella fused to hypandrium, with 2 moderately long setae apically. Left surstylus ( Fig. 226 ) with upper lobe divided; lower part with markedly developed surstylar comb and additional internal broad apophysis bearing 2 very long setae, upper part long, digitiform, with 1 subapical seta. Right epandrial lamella ( Fig. 226 ) subtriangular. Right surstylus subtriangular ( Fig. 225 ), divided at apex, with several long unmodified setae. Hypandrium with two processes at apex, lacking setae. Phallus short.

Female

Unknown.

Material examined

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

Etymology

The specific name refers to the brown infuscate wings. Distribution

Singapore.

Habitat and seasonal occurrence

Ths single known specimen was collected in mangrove, recorded in December.

Remarks

The new species can be readily distinguished from other species of Stilpon described from Singapore and from the Oriental Region because S. nigripennis sp. nov. is the only species lacking R 2+3. In the Palaearctic Region an abbreviated vein R 2+3 is present in S. paludosa (Perris, 1852) and S. delamarei ( Séguy, 1950) both known from the Pyrenees and an unnamed species taken from Tajikistan ( Shamshev & Grootaert 2005d). The relationships of S. nigripennis sp. nov. are unresolved beyond inclusion within the S. divergens group.

Figures

Figs 225-228. Stilpon nigripennis sp. nov., ♂. 225. right epandrial lamella. 226. epandrium with cerci. 227. left surstylus. 228. gland-like structures (dark stiple) on abdomen, dorsal view.