Stilpon seeluang, 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 : 326-327

Stilpon seeluang , new species

( Figs. 30-35 )

Material examined. – Holotype - male. THAILAND: Loei province, Na Haeo , FIRS, near waterfall, sample n 20013, 23 May.2000, coll. P. Grootaert ( SWU).

Paratypes – 2 males, 7 females, same data as in holotype. Na Haeo , FIRS, Malaise trap along a dry deciduous forest, coll. Verapong Kiatsoonthorn & P. Grootaert : 1 male, 3-10 Sep.1999; 1 female, 10-17 Sep.1999; 1 male, 1 female, 8- 15.Oct.1999; 1 female, 4-27.Aug.2000; 1 male, 3-10 Mar.2001; 1 male, 18-25 Mar.2001; 1 female, 25 Mar.2001 - 1 Apr.2001 ; 1 female, 29 Apr.-6 May.2001; 1 female, 20-29 May.2001; 2 females, 29 May.-4 Jun.2001; 1 male, 17-24 Jun.2001; 1 female, 29-5.Aug.2001; 1 male, Na Haeo , Chang Tok Waterfall, river bed, sample n 23035, 17 Jun.2003 , coll. P. Grootaert (coll. SWU, RBINS & ZRC).

Diagnosis. – Species with yellow thorax. Hind femur in apical 2/3 and tarsomere 5 of all legs (usually more distinctly on fore leg) brownish yellow; otherwise legs yellow. Male: mid femur with 4 yellowish ventral bristles in basal part, hind trochanter with 2 black spinules.

Description. – Male. Head black in ground-colour, with minute ocellars and short inner verticals. Antenna yellow. Postpedicel nearly 2.0 times longer than wide. Style about 5 times longer than postpedicel. Palpus pale yellow, small.

Thorax almost wholly yellow. Scutum entirely tomentose; with 2 brownish, more or less rounded, distinctly bordered, posterolateral spots including postalar calli; scutellar margins and postnotum brownish; pleural sutures (especially in darker specimens) brownish in varying extent. Postpronotal bristle short, hardly prominent. Dorsocentrals in multiple rows, complete posteriorly. Acrostichals 2-serial, complete posteriorly.

Legs with colour pattern: hind femur in apical 2/3 and tarsomere 5 of all legs (usually more distinctly on fore leg) brownish yellow; otherwise legs yellow. Hind trochanter ( Fig. 31 ) with 2 black spinules. Mid femur ( Fig. 30 ) slender, with 1 long anterior subapical bristle, bearing 4 yellow to brownish yellow, rather long, ventral bristles in basal half. Hind femur (viewed laterally) evenly thickened toward middle, with 1 row of short (3-4 subapical bristles longer) anteroventral bristles and some short dorsal bristles in basal part. Fore tibia lacking prominent bristles. Mid tibia straight, rather slender, lacking prominent ventral spinules. Hind tibia slightly arcuate, with ventral setulae more distinctly prominent, posterior apical comb unmodified.

Wing ( Fig. 32 ) normally developed, covered with uniform microtrichia; almost uniformly infuscate, somewhat deeper along longitudinal veins. Costal vein with ordinary short setulae on anterior margin. Vein R2+3 about 3 times longer than Rs. Distance between apices of R2+3 and R4+5 1.2-1.3 times longer than distance between apices of R1 and R2+3. R4+5 and M slightly divergent and evenly arcuate in apical part. Halter with contrast black, elongate knob and pale yellow stem.

Abdomen largely yellow, becoming darker toward hypopygium, with segments (except segment 8) weakly sclerotized and subequal in length, covered mostly with scattered ordinary pale setulae, lacking gland-like structures. Segments 1-2 unmodified. Segment 8 short, bearing moderately long bristles.

Hypopygium ( Fig. 33 ) dark brown, rather small. Hypandrium with 2 long bristles in apical part. Epandrium completely divided. Left epandrial lamella small, fused to hypandrium, with 2 minute bristles in apical part. Left surstylus with upper lobe ( Fig. 34 ) divided; lower part small, lacking surstylar comb, upper part elongate oval, with 1 short bristle. Right surstylus ( Fig. 35 ) with deep excision, lacking spines. Left cercus unbranched, digitiform, lacking apical spines and long bristles in basal part. Right cercus consisting of two short lobes, lacking spines. Phallus short.

Female. In most respects identical to male. Palpus brownish yellow. Hind trochanter lacking black spines. Terminalia shortened. Segment 8 normally sclerotized. Proximal margin of sternite 8 straight, without 2 anteriorly directed rods. Apex of sternite 8 hinged and partially separated from base. Sternite 10 uniformly sclerotized, not fused with ventroapical margin of tergite 8. Cercus elongate oval, brownish yellow, clothed in setulae of different length.

Measurements. – Body length 1.4-1.7 mm, wing length 0.9- 1.0 mm.

Etymology. – “See” (colour in Thai) “luang” (yellow in Thai), refers to the yellow colour of the thorax.

Phylogenetic relationships. – The relationships of this species are unresolved beyond inclusion within the S. seeluang species group.

Distribution and seasonal occurrence. – Thailand. Only known from Northeast Thailand, Loei province. Quite common and recorded from March till October.

Figures

Figs.30-35.Stilpon seeluang, new species, male.30, mid leg, anterior view, 31, hind leg, anterior view, 32, wing, dorsal view, 33, hypopygium, ventral view, 34, upper lobe of left surstylus, dorsal view, 35, right surstylus, dorsal view. Scale bar: 0.1 mm.