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

description: Hybos steatopygus sp. nov.
(Figs 168–173, 273, 299)
Type material. HOLOTYPE ♂: THAILAND, Chiang Mai Province, Doi Phahompok National Park, Kiewlom1 / montane forest, 20°3.549'N, 99°8.552'E, 2174 m, 21–28.v.2008, Malaise trap, P.Wongchai [T6100] (QSBG). PARATYPES: 16♂, 6♀, same data as holotype; 20♂, 3♀, 28.v.-7.vi.2008 (QSBG and NMWC).
Additional material. 3♀, same data as holotype, 28.v.-7.vi.2008; 3♂, 3♀, Doi Phaluang, 20°1.06'N, 99°9.581'E, 1449 m, 21–28.v.2008, 7–14.vi.2008; 2♂, 5♀, Mae Fang Hotspring, 19°57.961'N, 99°9.355'E, 569 m, 7–14.vi.2008 (QSBG and NMWC).
Etymology. A concatenation of Latin and Greek meaning ‘fat buttocks’, in reference to the globose male terminalia.
Diagnosis. A species with black thorax, hind femur black with a yellow apex, mid and front femora yellow but darkened dorsally. The mid tibia is clear yellow with only short hairs apart from very long and strong bristles dorsally near the middle. A dorsal seta is present on the postpedicel of the antenna. The male abdomen is constricted basally with segments 2 and 3 slightly elongated.
Description. Male: body length 3.0– 3.5 mm. Head subshining black, thinly dusted; face yellowish black, especially on lower part. All setae dark, with some paler hairs on lower occiput behind mouth. Antenna greyish black; postpedicel ovate in lateral view, ~2X long as wide, 1 fine dorsal seta present; stylus bare, 4–5X long as postpedicel, apical 0.25 narrower, paler in certain lights. Mouthparts dark yellowish brown, palpus very narrow, with 1 distinct dark apical seta and a few smaller setae below. Thorax with ground colour black with pleura often somewhat paler brownish black, postalar callus yellowish anterolaterally, scutellum narrowly yellowish basally; scutum, scutellum and pleura subshining, rather thickly and coarsely dusted greyish with faint indications of more shining stripes along line of dc near anterior margin of scutum; acr ~2–4-serial, dc uniserial, small, fine except 1 strong posterior dc, not continued over prescutellar depression; 1 strong (upper) and 1 weaker (lower) npl; pa weak; scutellum with pair of strong black bristles and several fine marginal hairs. Legs with coxae black; F 1 and F 2 yellowish to yellowish brown; F 1 usually rather darker than F 2, sometimes blackish but both darker dorsally (especially F 2); T 1 yellowish brown, T 2 and T 3 yellow; anterior tarsus brownish, mid and posterior tarsi with basal 2 segments yellow, distal segments brownish. Coxae with mostly pale hairs, conspicuously long behind C 3; a few dark bristles anteroapically, especially on C 1. F 1 and F 2 without distinct pv fringe, entirely short-haired, apical circlet with only small fine setae. F 3 rather slender, only slightly inflated, widest 0.6–0.8 from base where ~1.5–1.8 as deep as at base; ventral spines black, comprising av series of ~9–11 bristles (as long as limb is deep on basal 0.8, much shorter and spine-like on distal 0.2) behind which on basal 0.3 are 3–4 somewhat shorter bristles; pv fringe with 2–3 black bristles on distal 0.2, otherwise with fine pale hairs becoming shorter proximally; 1 rather proclinate, distinctly curved, long bristle anteriorly at ~0.8 and usually another at ~0.5 from base. T 1 with distinct dark bristles dorsally at 0.6 from base and near tip, pv fringe of fine hairs hardly longer than limb is deep. T 2 with 1 very strong, black bristle ~0.9X long as limb dorsally at 0.25–0.3 from base and 1 similar bristle ventrally slightly beyond; apical circlet of 5–6 black bristles rather short except 1 anterior ~0.7X long as MT 2. T 3 slightly swollen apically, rather thinly covered with longish pubescent hairs; distinct black dorsal seta at 0.4 from base; no apical circlet apart from 1 distinct anterior and 1 pd setae. Front tarsi with short hairs apart from slightly longer paired dorsoapical seta on each segment and 1 short, rather stout ventrobasal on MT 1. MT 2 with short erect ventral bristle near base with 2–3 similar but shorter setae beyond, otherwise with short hairs. MT 2 short spinose ventrally. Wing membrane tinged brown, paler posteriorly; veins brown; stigma faint, brownish, reaching 0.8X distance between end of R 1 and R 2+3. Squamae with white fringes. Halter white. Abdomen subshining brownish black, thinly dusted; pregenital segments with all setae pale; segments 2 and 3 slightly constricted, elongate (somewhat longer than wide). Terminalia (Figs 168–171) globose, much wider than abdomen, black with setae dark. Right surstylus (Fig. 171) with long, narrow outer process and broader, internally directed inner process. Left surstylus (Fig. 170) broad, with short, curving, spine-like, dorsal process and longer, blunt, curving, ventral process. Hypandrium (Fig. 169) narrow, with narrow strongly curved process arising from left margin, with long curving bristles arising from base. Female. Differing from male as follows. Slightly smaller, body length 2.8–3.1 mm. F 3 with ventral spines uniserial, longer (1–2 about middle 2X long as limb is deep). Abdomen not constricted basally, segments 2 and 3 wider than long; shorter-haired but sternite 7 with long pale bristles on posterior margin. Terminalia (Figs 172, 173) with tergite 8 broad, almost encircling abdomen, with long setae on posterior margin. Sternite 8 (Fig. 172) bare, very narrow, irregularly upcurved distally. Sternite 10, small, Y-shaped, rather densely pilose.
Comment. Hybos steatopygus sp. nov. is only known from Doi Phahompok, in the Daen Lao Range along the border with Burma in the far north of Thailand (Fig. 273) and 48 (79 %) of 61 known individuals were captured above 2,000 m in moist hill evergreen forest. Despite extensive trapping efforts on Doi Phahompok, H. steatopygus sp. nov. has only been caught in a brief period between late May and early June (Fig. 299), coincident with the early part of the wet season. Hybos steatopygus sp. nov. can easily be separated from other Thailand species in which the hind femur is black with a yellow apex (H. men sp. nov.; H. particularis; H. ancistroides) by having a yellow mid femur which is darkened dorsally along its length. Based on morphology of the hypandrium, the species is probably quite closely related to H. bifurcatus Yang & Grootaert, 2006 and H. mengqingae Yang & Grootaert, 2006 from the Nanling Mountains in southeastern China and perhaps also H. sinclairi sp. nov. from Thailand. However, H. bifurcatus and H. mengqingae have entirely black legs and surstyli of very different morphology and H. sinclairi sp. nov. can be distinguished by the characters given in the key.
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 65-66, DOI: 10.11646/zootaxa.3690.1.1, http://zenodo.org/record/6329811