Stilpon lekkwar, 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 : 331-332

Stilpon lekkwar , new species

( Figs. 50-53 )

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

Paratypes – 1 male, 17-24 Jun.2001; 2 males, 17-24.IX.99; 1 female, 29 Apr.2001 - 6 May.2000 ; 1 female, 8-15 Apr.2001; 1 male, 30 Apr.-7 May.2000; 1 male, 1 female, 7-14 May.2000, same locality as in holotype, coll. P. Grootaert. 2 males, Khring Nam Tok , sample n 23041, 20 May.2003 , coll. P. Grootaert; 1 male, Na Haeo FIRS, Malaise trap n 2 in bamboo wood, 24 Apr.2003 (leg. P. Grootaert) . ( SWU, RBINS, ZRC).

Diagnosis. – Species with black thorax, very similar to S. lek but somewhat smaller, hind femur entirely yellow, male abdomen with gland-like structures between tergites 5-4, 4- 3 and 3-2. Halter pale brown.

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

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

Legs with fore tarsomere 5 blackish brown, mid and hind tarsomere 5 pale brown; otherwise legs yellow. Hind trochanter lacking spinules. Mid femur ( Fig. 50 ) with row of 4 brownish yellow bristles in basal 1/3, bearing 1 antero- and 1 posteroventral short spines just beyond middle. Hind femur (viewed laterally) evenly thickened toward middle; with 6- 7 long anteroventral and some prominent dorsal bristles. Fore tibia lacking prominent bristles. Mid tibia with rows of ventral spinules in apical half and 1 longer subapical spinule. Hind tibia unmodified.

Wing normally developed, covered with uniform microtrichia; almost uniformly infuscate, somewhat paler along posterior margin. Costal vein with ordinary short setulae on anterior margin. Distance between apices of veins R2+3 and R4+5 about 1.5 times longer than distance between apices of veins R1 and R2+3. R4+5 and M divergent and evenly arcuate in apical part. Halter pale, knob with slight brownish tinge.

Abdomen with tergites 1-2 unmodified. Narrow gland-like structures present between tergites 5-4, 4-3, and 3-2 ( Fig. 81 ). Tergites 3 and 4 shortened. Segment 8 with short bristles.

Hypopygium ( Fig. 51 ) dark brown. Hypandrium with 2 long bristles in apical part. Epandrium completely divided. Left epandrial lamella small, fused to hypandrium, bearing 2 long bristles in apical part. Left surstylus with upper lobe ( Fig. 52 ) undivided, with markedly developed surstylar comb. Right surstylus ( Fig. 53 ) rather small, rounded apically, lacking spines. Left cercus unbranched, elongate, digitiform, lacking spines, with 1 long, spine-like, ventral bristle in middle part and 3 thinner marginal bristles basally. Right cercus consisting of two lobes, lacking spines; left lobe slender, digitiform; right lobe small, rounded. Phallus long, hair-like, curved.

Female. In most respects identical to male. Mid femur with yellowish bristles in basal part, lacking black spines. Mid tibia lacking ventral spinules. Abdomen lacking gland-like structures. Terminalia elongate. Segment 8 stronger sclerotized than preabdomen. Proximal margin of sternite 8 without 2 anteriorly directed rods. Apex of sternite 8 not 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 1.2-1.4 mm, wing length 0.8- 0.9 mm.

Etymology. – “Lek” (small) “kwar” (more) refers to the fact that this species is even smaller than its sibling S. lek .

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

Distribution and seasonal occurrence. – Thailand. Known from one locality in Northeast Thailand only. Records from April, May and June, but one record also from September.

Figures

Figs. 50-53. Stilpon lekkwar, new species, male. 50, mid leg, anterior view, 51, hypopygium, ventral view, 52, upper lobe of left surstylus, dorsal view, 53, right surstylus, dorsal view. Scale bar: 0.1 mm.

Figs. 80-84. Details of male abdomen, dorsal view. 80, Stilpon lek, new species, 81, Stilpon lekkwar, new species, 82, Stilpon trilobatus, new species, 83, Stilpon malayensis, new species, 84, Stilpon paradoxus, new species; T – tergite. Scale bar: 0.1 mm.