Hybos ngachang PLANT 2013, sp. nov.
Creators: name: PLANT, ADRIAN R.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Hybotidae
Hybos
Hybos ngachang

description: Hybos ngachang sp. nov.
(Figs 113–117, 263)
Type material. HOLOTYPE ♂: THAILAND, Chiang Mai Province, Doi Phahompok National Park, Kiewlom1 / montane forest, 20°3.549'N, 99°8.552'E, 2174 m, 7–14.iv.2008, Malaise trap, K.Seesom [T6073] (QSBG). PARATYPES: 3♀, same data as holotype, 7–14.iv.2008, 28.iv.–7.v.2008; 1♂, Doi Phahompok National Park, Doi Phaluang, 20°1.06'N, 99°9.581'E, 1449 m, 28.iv.–7.v.2008 (QSBG and NMWC).
Additional material. 1♀, Chiang Mai Province, Huai Nam Dang National Park, Thung Buatong View Point, 19°17.56'N, 98°36.029'E, 14–21.iv.2008 (QSBG).
Etymology. From Thai nga-chang, elephant tusks, after the paired tusk-like setae on the male mid femur.
Diagnosis. A black legged species with largely dark setae on coxae, stylus micropilose on basal 0.8 and 2–3 strong setae on the postpedicel. The male mid and hind legs are characteristically twisted and swollen with unusual chaetotaxy. The discal cell is short in both sexes, especially the male in which crossvein dm-cu closing the cell is strongly oblique.
Description. Male: body length 2.5 mm. Head subshining black dusted greyish; face yellowish black; occipital setae black, setae on lower occiput hardly paler. Antenna black; postpedicel ovate in lateral view, ~2.5X long as wide, with 2 (sometimes 3) distinct anteriorly directed dorsal setae, slightly longer than postpedicel; stylus 4–5X long as postpedicel, micropilose on proximal 0.8, hairs shorter than stylus is deep; apical 0.2–0.25 bare. Mouthparts blackish, palpus narrow, with distinct apical and ventral hairs. Thorax with ground colour black; postalar callus laterally, scutellum narrowly at base and pleura vaguely about base of wing yellowish; dusted brownish grey; acr 2-serial; acr and dc fine and hair-like, posterior dc and acr before prescutellar area conspicuously stronger although very fine; 1 fine pa; 1 strong and 1 weak npl; a few small setae about and behind postpronotal lobe; 1 pair of fine sct with smaller hairs on posterior margin of scutellum. Legs subshining black, thinly dusted greyish; ‘knees’ of all legs vaguely paler. Coxae with hairs and bristles mostly black or dark brown. F 1 with ventral fringe of dark hairs about as long as limb is deep; av fringe much shorter. F 2 with 2 very strong closely apposed bristles ventrally, arising from slight swelling 0.3 from base (Fig. 117); 1 strong dorsal bristle near base and av fringe of ~8 setae, becoming longer distally. F 3 strongly but unevenly inflated, widest 0.7–0.8 from base, ventral margin slightly concave in profile; ventral spines comprising ~20 stout denticles which are very short proximally, becoming longer and spine-like distally but always much shorter than limb is deep; series of longer bristles anteroventrally on distal 0.4; pv fringe yellowish brown, numerous, somewhat longer distally than near base where more or less indistinguishable from other numerous fine hairs and bristles; dorsum with numerous fine hairs becoming longer distally. T 1 with setae becoming longer distally, 1 strong and 1–2 smaller dorsoapicals; ventrally with minute pile becoming stronger distally and continuing beneath MT 1.T 2 twisted, inflated subapically (Fig. 117); 2–3 distinct dorsal bristles; rather densely covered with strong hairs, strongest ventrally and near tip where stouter and bristle-like.T 3 stout, narrower basally, widest near middle and tip viewed anterodorsally; rather densely covered with fine long hairs, some of which are about as long as limb is deep; fine yellowish brown pubescent pile ventrally and posteriorly, continued over first and second tarsomeres. Tarsomeres 1–3 on anterior and mid legs with distinct fine dorsoapical bristles. MT 3 weakly spinose ventrally. Wing membrane faintly brownish, slightly darker apically; veins brown. Stigma distinct, brown; on basal half, very narrowly separated from anterior margin of wing by area of paler membrane; short, reaching costa ~0.7 distance between end of R 1 and R 2+3. Cell dm very short, hardly longer than wide; produced posteroapically, with crossvein dm-cu oblique; upper vein (M 1) ~3X long as cell. Squamae with pale fringes. Halter white. Abdomen black, dusted greyish, subshining. Hairs about base mostly pale becoming blackish distally; long dark bristles on tergite 2 laterally; sternite 5 with very strong yellowish brown lateral bristles; sternites 5–8 with increasingly long bristles on posterior margin. Terminalia (Figs 113–116) with black bristles. Left epandrial lamella with slight process on inner margin bearing numerous fine setae. Left surstylus (Fig. 116) broadly triangular in lateral view, with 2–3 (depending on view) more or less pointed apical processes; much narrower in dorsal view with two separate groups of short, stout setae on inner face. Right epandrial lamella (Fig. 114) elongate, with long bristles, bearing two apical processes. Hypandrium (Fig. 115) with elongate apical process at the base of which is 1 very long bristle. Female. Front legs similar to male but T 1 with 2–3 fine bristles dorsally, distinct from surrounding hairs. F 2 simple, complete fringe of fine pv hairs, ventral and av fringes longest on proximal 0.5. T 2 simple, distinct fine bristles dorsally at 0.2, 0.5 and 0.8 from base; equally strong anteroventrals at 0.8 and apically. F 3 widest 0.6–0.8 from base; ventral series of ~20 short spines not as stout as in male, not becoming longer distally; av fringe of ~5–7 fine bristles with more numerous smaller hairs in between; pv fringe of fine hairs rather weak, hardly distinguished from surrounding hairs proximally, becoming stronger and longer distally; a few fine longish ad hairs subapically. T 3 simple, short haired, dorsal hairs somewhat longer near tip. Wing with cell dm obviously longer than wide, not produced posteroapically, crossvein dm-cu perpendicular; upper vein (M 1) ≤2X long as cell. Stigma on basal half not separated from anterior margin of wing by area of paler membrane. Abdomen generally shorter haired than male, hairs more consistently dark; sternite 5 without very strong lateral bristle. Sternite 8 rather more strongly sclerotized than tergite 8, with a few distinct dark bristles on disc. Sternite 10 small, minutely pilose.
Comment. Hybos ngachang sp. nov. may be related to H. ancistroides Yang & Yang, 1986 from Guangxi, China, based on the shape of the hypandrium. However that species has the mid femur apically yellow, hind tibia yellow basally, the surstyli are of different form and it apparently lacks the extraordinary modifications of the mid and hind legs found in H. ngachang sp. nov. The high level of sexual dimorphism exhibited by this species is unusual in Hybos. Hybos ngachang is known only from Hill Evergreen and Moist Hill Evergreen forests on mountains of the Daen Lao Range along the Burmese border in northern Thailand at Doi Phahompok and Huai Nam Dang (Fig. 263). All specimens were collected in April or May, at the end of the cool dry season and start of the wet season.
description: Published as part of PLANT, ADRIAN R., 2013, The genus Hybos Meigen (Diptera: Empidoidea: Hybotidae) in Thailand, pp. 1-98 in Zootaxa 3690 (1) on pages 47-48, DOI: 10.11646/zootaxa.3690.1.1, http://zenodo.org/record/6329811