Stilpon khorngkeun, Shamshev & Grootaert, 2004

Shamshev, Igor V. & Grootaert, Patrick, 2004, A Review Of The Genus Stilpon Loew, 1859 (Empidoidea: Hybotidae) From The Oriental Region, Raffles Bulletin of Zoology 52 (2), pp. 315-346 : 328-330

Stilpon khorngkeun , new species

( Figs. 40-44 )

Material examined. – Holotype - male, THAILAND: Loei province, Na Haeo, FIRS, Malaise trap in bamboo forest at Na Haeo FIRS, 1 male, 7-14 May.2000, coll. P. Grootaert ( SWU).

Paratypes – Same data as in holotype : 1 male, 17-24 Sep.1999; 1 male, 24-30 Apr.2000; 1 male, 13-20 May.2001; 1 male, 29 May.-4 Jun.2001; 1 male, 7-14 Jul.2001, coll. Verapong

Kiatsoonthorn & P. Grootaert; 2 males, Na Haeo FIRS , Malaise trap n 1 in bamboo wood, 25 May.2003 (leg. P. Grootaert); 3 males, Na Haeo FIRS , base of waterfall, sample n 23029, 16 May.2003 (leg. P. Grootaert). (in coll. SWU, RBINS & ZRC) .

Diagnosis. – Species with black thorax, differing from other species from the Oriental region by R4+5 strongly curved in apical part and by brown hind tarsomere 1.

Description. – Male. Head black in ground-colour, with minute anterior ocellars, short (half as long as inner verticals) posterior ocellars and long inner verticals. Antenna yellow. Postpedicel nearly 2.0 times longer than wide. Style about 5 times longer than postpedicel. Palpus brownish yellow.

Thorax brown. Scutum entirely tomentose. Postpronotal bristle long, inclinate. Dorsocentrals in multiple rows, complete posteriorly. Acrostichals 2-serial, complete posteriorly.

Legs with colour pattern: hind femur brownish yellow in apical 2/3, tarsomere 5 of all legs and hind tarsomere 1 brown; otherwise legs yellow. Hind trochanter lacking spinules. Mid femur ( Fig. 40 ) slender, with long pale ventral bristles in extreme base and 2 ventral yellowish spines nearer to middle. Hind femur (viewed laterally) evenly thickened toward middle, with short anterodorsal bristles (3 subapicals longer), lacking prominent dorsal bristles near base but with prominent dorsal bristles in apical part. Fore tibia with short, hardly prominent, brownish, posterodorsal bristle at apex, lacking prominent ventral bristles. Mid tibia considerably shorter than mid femur, with rows of ventral spinules and 1 longer subapical spinule. Hind tibia unmodified.

Wing ( Fig. 41 ) normally developed, covered with uniform microtrichia, finely infuscate. Costal vein with ordinary short setulae on anterior margin. Veins R2+3 and R4+5 thickened, darker than other veins (especially R4+5). Vein R2+3 about 3 times longer than Rs. Distance between apices of R2+3 and R4+5 nearly 1.5 times shorter than distance between apices of R1 and R2+3. R4+5 strongly curved at apex. R4+5 and M divergent in apical part. Vein CuA1 not quite reaching wing margin. Halter with brown elongate knob (one specimen had a very dark knob) and pale stem.

Abdomen largely yellowish brown, bearing mostly scattered dark setulae which are longer on pregenital segments, with all tergites (except segment 8) of subequal in length, tergites 1-2 unmodified. Narrow gland-like structures present between tergites 4-3 and 3-2.

Hypopygium ( Fig. 42 ) brown. Hypandrium with 2 strong bristles in apical part. Epandrium completely divided. Left epandrial lamella small, fused to hypandrium, with 2 moderately long bristles in apical part. Left surstylus with upper lobe ( Fig. 43 ) undivided, with markedly developed surstylar comb. Right surstylus ( Fig. 44 ) moderately large, sublinear, more or less rounded at apex, lacking spines. Left cercus unbranched, digitiform, fairly long, lacking spines, with 1 strong ventral bristle in middle part and 1 thinner marginal bristle basally. Right cercus consisting of two lobes, lacking spines; left lobe elongate, somewhat broadened toward apex; right lobe short, tapered toward apex. Phallus long, hair-like, curved.

Female. Unknown.

Measurements. – Body length 1.4-1.7 mm, wing length 0.9- 1.2 mm.

Etymology. – “Khorng” (curved) “keun” (upwards) refers to the fact that the vein r4+5 is strongly curved upward.

Phylogenetic relationships. – The relationships of this species are unresolved beyond inclusion within the S. divergens group. Presumably the sister species to S. lekkwar based on the presence of apical spines on the middle part of the male left surstylus.

Distribution and seasonal occurrence. – Thailand. Only known from one locality in Northeast Thailand in the Loei province. Records are from April till June and one more record in September.

Figures

Figs. 40-44. Stilpon khorngkeun, new species, male. 40, mid leg, anterior view, 41, wing, dorsal view, 42, hypopygium, ventral view, 43, upper lobe of left surstylus, dorsal view, 44, right surstylus, dorsal view. Scale bar: 0.1 mm.