Stilpon nhamdam, 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 : 334-335

Stilpon nhamdam , new species

( Figs. 60-63 )

Material examined. – Holotype - male, THAILAND: Loei province, Na Haeo, river banks in gallery forest at Na Haeo FIRS, sample n 20026, 27 May.2000, coll. P. Grootaert ( SWU).

Paratypes – 1 female, same data as in holotype ; 1 male, Na Haeo , base waterfall at FIRS, sample n 21033, 6 May.2001, coll. P. Grootaert ; 1 male, 1 female, Na Haeo , in gallery forest along stream at FIRS, sample n 21035, 6 May.2001, coll. P. Grootaert ; 7 males, 8 females, Dan Sai , along pond in village (between school and market), sample n 21038, 8 May.2001, coll. P. Grootaert ; 1 male, Na Haeo , gallery forest along stream at FIRS, sample n 21044, 8 May.2001, coll. P. Grootaert ; 4 males, 7 females, Khring Nam Tok , river bed, sample n 21046, 9 May.2001, coll. P. Grootaert ; 2 males, Khring Nam Tok , sample n 23041, 20 May.2003, coll. P. Grootaert ; 2 males, 2 females, Chang Nam Tok , river bed, sample n 21047, 9 May.2001, coll. P. Grootaert ). (in coll. SWU, RBINS, ZRC).

Diagnosis. – Species with black thorax and mostly yellow hind femur. Male: mid femur with basal swelling and long black anteroventral spine.

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

Thorax dark 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 in apical 2/3, mid femur in apical 1/3, fore tibia entirely (paler at base), fore tarsomere 1 (becoming paler toward apex), mid and hind tarsomere 5 brownish, fore tarsomere 5 contrast brown; tarsomeres 2-4 pale yellow; otherwise legs yellow. Mid coxa with 2 brown bristles on outer side. Hind trochanter lacking spinules. Mid femur ( Fig. 60 ) with swelling in basal part, bearing long black anteroventral spine near middle, 2 shorter brownish posteroventral spines and 1 long brownish yellow bristle in extreme base. Hind femur (viewed laterally) evenly thickened toward middle, with row of 7 anterodorsal subapical bristles which scarcely longer than femur is deep and row of well prominent dorsal bristles in basal half. Fore tibia lacking prominent ventral bristles. Mid tibia shortened, with hardly prominent ventral spinules in apical part and 1 longer spinule at apex. Hind tibia unmodified.

Wing normally developed, covered with uniform microtrichia, more or less uniformly infuscate. Vein R2+3 about 3.0 times longer than Rs. Distance between apices of R2+3 and R4+5 subequal to distance between apices of R1 and R2+3. R4+5 and M strongly divergent in apical part. Halter with contrast black elongate 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. 61 ) brown. Hypandrium with 2 long bristles in apical part. Epandrium completely divided. Left epandrial lamella small, fused to hypandrium, with 2 long bristles in apical part. Left surstylus with upper lobe ( Fig. 62 ) undivided, with markedly developed surstylar comb. Right surstylus ( Fig. 63 ) moderately large, elongate, sublinear, more or less rounded at apex, lacking spines. Left cercus unbranched, digitiform, fairly long, lacking spines, with 1 strong ventral bristle and 2 thinner long marginal bristles basally. Right cercus consisting of two lobes, lacking spines; left lobe digitiform, fairly long, somewhat broadened in apical part; right lobe short, broad, rounded at apex. Phallus long, hair-like, curved.

Female. In most respects identical to male. Mid femur with row of yellowish bristles. Abdomen paler. Terminalia elongate. Segment 8 strongly sclerotized. 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 1.4-1.7 mm, wing length 0.9- 1.2 mm.

Etymology. – “Nham” (spine), “dam” (black) refers to ventral black spine on the mid femur.

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

Distribution and seasonal occurrence. – Thailand. Only know from Loei province in Northeast Thailand, but there known from various sites. Quite common in May. Not found in the Malaise trap, although it was common along the nearby stream.

Figures

Figs. 60-63. Stilpon nhamdam, new species, male. 60, mid leg, anterior view, 61, hypopygium, ventral view, 62, upper lobe of left surstylus, dorsal view, 63, right surstylus, dorsal view. Scale bar: 0.1 mm.