Stilpon Loew 1859
- Dataset
- The fast-running flies (Diptera, Hybotidae, Tachydromiinae) of Singapore and adjacent regions
- Rank
- GENUS
Classification
- kingdom
- Animalia
- phylum
- Arthropoda
- class
- Insecta
- order
- Diptera
- family
- Hybotidae
- genus
- Stilpon
description
Stilpon is recognized from other drapetine genera that occur in the Oriental Region by the following combination of features: eyes contiguous on face, frons with sides nearly parallel; antenna with dorsoapical arista-like stylus; wing with cell br much shorter than cell bm, A 1 very weak or absent; abdominal tergites lacking squamiform setae; male terminalia with single rod-shaped ejaculatory apodeme.
diagnosis
Diagnosis Very small flies, usually 1.0 - 1.5 mm (rarely 2.0 - 2.5 mm). Eyes contiguous on face. Ommatidia slightly enlarged below antennae. Frons linear to sublinear, narrow to fairly wide. Face strongly convex. Gena barely extended below eye. Ocellar tubercle with 2 pairs of bristles. One pair of prominent inclinate vertical bristles. Antennae with pedicel large and globose, bearing long ventral preapical seta; postpedicel small, ovate, with very prominent dorsoapical extension; stylus dorsoapical, long. Palpus elongate-ovate, with distinct apical seta. Thorax blackish brown to yellow in ground-colour. Scutum shiney or tomentose; anepisternum largely shiney. Thoracic bristles mostly only slightly prominent. Metaepimeron large. Halter with knob yellow to black, rarely absent. Wing normally developed or sometimes shortened; nearly hyaline or with distinct pattern; Rs originating halfway along R 1; vein R 2 + 3 complete or incomplete; cell br short, distinctly less than length of cell bm; crossvein bm-cu nearly transverse; A 1 and crossvein CuA 2 absent. Legs short, often with distinct colour pattern; fore femur thickened; mid femur slender to barely thickened, usually armed with bristles and spinules or spines arranged in specific patterns; fore tibia more or less spindle-like; mid tibia often armed with ventral spinules; hind tibia slender, lacking prominent bristles, rarely with modified posterior apical comb. Abdomen with segments 1 - 7 lightly sclerotised, rarely segments 1 - 2 modified; squamiform setae absent. Gland-like intersegmental structures present or absent. Male terminalia asymmetrical, rotated 90 ° to right. Epandrium completely divided. Left epandrial lamella small and fused to hypandrium. Left surstylus divided into 3 (or 4) lobes; upper lobe with or without surstylar comb. Right epandrial lamella usually large, positioned ventrally. Right surstylus large to moderately large, undivided, sometimes with apical spines. Cerci, including subepandrial sclerite, fused together basally, rarely fused completely into one large lobe, sometimes greatly reduced and bearing apical spines. Phallus elongate, well sclerotised, hair-like or, rarely, straight or very short and rather weakly sclerotised; single rod-shaped ejaculatory apodeme present. Female similar to male except ordinary setation on mid legs and unmodified abdominal segments 1 - 2; abdomen always without gland-like structures; terminalia short to elongate; tergite 8 not fused laterally with sternite 8; sternite 8 entire, or with apex hinged and partly or completely separated from base. Cercus elongate-ovate or broadly ovate.
discussion
Remarks The species of the genus Stilpon are distributed in the Afrotropical (2 species), Nearctic (13 species), Oriental (26 species) and Palaearctic (12 species) regions, with 54 currently known species (including 5 new species recognised herein from Singapore). Smith (1965) described the first Oriental species Stilpon divergens. Shamshev & Grootaert (2004 b) published 15 new species of Stilpon found in northeastern Thailand above 500 m altitude. Two short papers followed: first with two new species from Cambodia (Shamshev & Grootaert 2006) and second with two new species from southern China (Shamshev et al. 2005). Cumming & Cooper (1992) recognised three informal species groups of Stilpon (S. varipes group, S. graminum group, and S. divergens group), and Shamshev & Grootaert (2004 b) added the S. seeluang group. Species of Stilpon are quite rare at low altitudes in the tropics as is demonstrated here too. On the other hand they are quite common at higher altitudes as is shown by the material collected during the TIGER project in Thailand. In the latter survey project, Stilpon is as common and diverse as Platypalpus and Elaphropeza and many new species await description. Species of this genus inhabit different biotopes but usually occurring in the low-lying vegetation zones (Collin 1961; Chvála 1975; Cumming & Cooper 1992; Przhiboro & Shamshev 2007). The key given below is limited to Stilpon from low altitudes including only S. laawae of the 15 species known from northern Thailand (Shamshev & Grootaert 2004 b).
Name
- Homonyms
- Stilpon Loew 1859
- Stilpon Loew 1859
- Stilpon