Stilpon neesoonensis, 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 : 133-136

Stilpon neesoonensis sp. nov.

Figs 220-224

Diagnosis

Species with yellow thorax, scutum with brownish patch above wing base, katepisternum (= sternopleuron) and meron (= hypopleuron) brownish in lower part; metanotum broadly brownish in middle; hind femur brownish in apical part; wing distinctly maculate, R 2+3 and R 4+5 thickened, R 4+5 strongly curved in apical part.

Description

Male LENGTH. Body 1.2 mm, wing 1.1 mm.

HEAD. ( Fig. 220 ) Black. Occiput subshining, finely greyish pollinose. Two moderately long vertical bristles present. Frons linear with sides nearly parallel, rather broad, entirely tomentose, subshiney. Ocellar tubercle with minute setulae. Antenna with scape and pedicel brownish yellow, postpedicel yellow. Palpus brownish in apical part, otherwise yellow, with moderately long, brownish subapical bristle.

THORAX.Yellow in ground-colour.Scutum entirely tomentose, with large brownish patch above wing base; katepisternum and meron brownish in lower part; metanotum broadly brownish in middle. Postpronotal bristle long, inclinate. Dorsocentral bristles in multiple rows, complete posteriorly. Acrostichal bristles 2-serial, complete posteriorly.

LEGS. Almost wholly yellow, only hind femur somewhat brownish in apical part. Hind trochanter lacking spinules. Fore femur markedly thickened, with rows of moderately long anteroventral and posteroventral bristles. Fore tibia spindle-like, with ordinary setation. Mid femur ( Fig. 221 ) slender, with 4 moderately long ventral bristles and 1 long subapical bristle anteriorly. Mid tibia lacking ventral spinules and prominent bristles. Hind femur (viewed laterally) evenly thickened towards middle, with 1 row of short anteroventral bristles 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; distinctly maculate, cells r 1, basal part of r 2+3, whole r 4+5, br and wing apex hyaline, otherwise wing brownish (deeper on middle part). Costal vein with short setulae along anterior margin. R 2+3 and R 4+5 thickened. R 2+3 short, nearly as long as Rs. Distance between apices of R 2+3 and R 4+5 about 3.0 times longer than distance between apices of R 1 and R 2+3. R 4+5 strongly curved toward costa in apical part. R 4+5 and M 1+2 strongly divergent before wing apex. Halter with brownish yellow knob and yellow stem.

ABDOMEN. Tergites 1 and 2 unmodified. Gland-like structure present between tergites 2 and 3, 3 and 4 and 4 and 5.

TERMINALIA. Brown ( Figs 222-224 ). Cerci fused into one rather short and subrectangular lobe, with spines. Epandrium completely divided. Left epandrial lamella fused to hypandrium, with 2 long setae apically. Left surstylus ( Fig. 224 ) with upper lobe divided; lower part with markedly developed surstylar comb and additional internal apophysis bearing 3 long setae, upper part short, digitiform, with 1 subapical seta. Right epandrial lamella ( Fig. 223 ) subtriangular, covered with numerous unmodified setae of different lengths. Right surstylus not prominent. Hypandrium with 2 moderately long, strong setae sitting on tubercle in apical part. Phallus short.

Female

Unknown.

Material examined

Holotype ♂

SINGAPORE: Nee Soon, 3 December 2005, swamp forest, Mal 1 (reg. 25436, leg. P.G.; in ZRC).

Etymology The specific name refers to the type locality, Nee Soon.

Distribution Singapore.

Habitat and seasonal occurrence

This single known specimen was collected in a swamp forest, recorded from December.

Remarks

The new species belongs to the S. divergens group of species. Within this unit S. neesoonensis sp. nov. is closely related to S. malayensis . However, the latter can be readily distinguished from the new species

in the wholly brown scutum (vs. largely yellow). It should be noted that within the S. divergens group only these two species have a partly yellow thorax.

Figures

Figs 220-224. Stilpon neesoonensis sp. nov., ♂. 220. head lateral, lateral view. 221. mid leg, anterior view. 222. right epandrial lamella, lateral view. 223. epandrium with cerci, dorsal view. 224. left surstylus and cercus, dorso-lateral view.