Stilpon lek, 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 : 330-331

Stilpon lek , new species

( Figs. 45-49 )

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

Paratypes – 1 male, same locality as in holotype, sample n 98064, 23. V.1998, coll. P. Grootaert; 2 females, same data as in holotype ; 2 males, 1 female, Na Haeo , near stream at FIRS, sample n 2026, 27 May.2000, coll. P. Grootaert ; 1 male, Na Haeo , near stream on mud banks at FIRS, sample n 21035, 6 May.2001, coll. P. Grootaert ; 1 male, 2 females, Na Haeo , FIRS Malaise trap, 18-25 Dec.2001, coll. P. Grootaert ; 1 male, 1 female, same locality as in holotype, sample n 21033, 6 May.2001, coll. P. Grootaert. ( SWU, RBINS, ZRC).

Diagnosis. – Species with black thorax, fore tibia yellow. Male: mid femur with 1 short black anteroventral spine just beyond middle, abdomen with gland-like structures between tergites 4-3 and 3-2. Halter contrastingly black.

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, small, subtriangular.

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 colour pattern: hind femur in apical 2/3 yellowish brown to brownish, fore tarsomere 5 dark brown, mid and hind tarsomere 5 pale brown; in darker specimens mid and hind coxae, mid and hind tibiae and mid femur at apex with brownish tinge. Hind trochanter lacking spines. Mid femur ( Fig. 45 ) with 4 yellowish ventral bristles in basal half and 1 short black anteroventral spine just beyond middle. Hind femur (viewed laterally) evenly thickened toward middle; with row of 5 long anteroventral bristles in apical part 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 ( Fig. 46 ) normally developed, covered with uniform microtrichia; almost uniformly infuscate, somewhat paler along posterior margin. Costal vein with ordinary short setulae on anterior margin. Vein R2+3 about 3 times longer than Rs. Distance between apices of veins R2+3 and R4+5 about 1.3 times longer than distance between apices of veins R1 and R2+3. R4+5 and M divergent and evenly arcuate in apical part. Halter with contrast black, elongate knob and pale yellow stem.

Abdomen largely pale brown, with segments (except segment 8) weakly sclerotized, segment 8 wholly brown. Segments 1-2 unmodified. Narrow gland-like structures present between tergites 4-3 and 3-2 ( Fig. 80 ). Tergites 3 and 4 shortened. Almost all tergites with scattered minute brownish setulae, tergites 7 and 8 with moderately long bristles. Sternites with similar setation but sternites 3 and 4 bearing 1 pair of inclinate bristles.

Hypopygium ( Fig. 47 ) dark brown. Hypandrium with 2 strong bristles in apical part. Epandrium completely divided. Left epandrial lamella small, fused to hypandrium, bearing 2 short bristles in apical part. Left surstylus with upper lobe ( Fig. 48 ) undivided, broadened toward apex, with markedly developed surstylar comb. Right surstylus ( Fig. 49 ) rather small, rounded apically, sublinear, lacking spines. Left cercus unbranched, elongate, digitiform, lacking spines, with 1 long ventral bristle in middle part and several shorter marginal bristles basally. Right cercus consisting of two lobes, lacking spines; left lobe elongate, digitiform, somewhat broadened toward apex; right lobe small, rounded, with 2 long apical bristles. Phallus long, hair-like, curved.

Female. In most respects identical to male. Fore tarsomere 5 pale brown, mid and hind tarsomere 5 pale yellow. Mid femur with yellowish ventral bristles only. Mid tibia lacking spinules. Halter with pale brownish knob. 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 1.5-1.9 mm, wing length 0.9- 1.2 mm.

Etymology. – “Lek” means small in Thai and it refers to the small size of the species

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. Records mainly in May, but one record also in December.

Figures

Figs. 45-49. Stilpon lek, new species, male. 45, mid leg, anterior view, 46, wing, dorsal view, 47, hypopygium, ventral view, 48, left surstylus, dorsal view, 49, right surstylus, dorsal view; v br – ventral bristle. 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.