Hybos ancistroides Yang & Yang
Creators: name: PLANT, ADRIAN R.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Hybotidae
Hybos
Hybos ancistroides

description: Hybos ancistroides Yang & Yang
(Figs 9–18, 243, 284)
Hybos ancistroides Yang & Yang, 1986: 80.
Material examined. 2♂, 5♀, THAILAND, Kamphaeng Phet Province, Mae Wong National Park, Chong Yen, 16°5.212'N, 99°6.576'E, 1306 m, 12–19.xi.2007, 10–17.xii.2007, Malaise trap, C. Piluek & A. Inpuang; 1♂, 1♀, Nakhon Si Thammarat Province, Namtok Yong National Park, TV aerial, 8°14.262'N, 99°48.289'E, 966 m, 14– 21.vii.2008; 2♂, 4♀, Chiang Mai Province, Doi Phahompok NP, Doi Phaluang, 20°1.06'N, 99°9.581'E, 1449 m, 7– 14.xi.2007; 2♂, 1♀, Chiang Mai Province, Doi Chiangdao National Park, Pakea Station, Evergreen forest, 19°18'50.7"N 98°49'57.8"E, 1560 m, 4–10.ix.2009, 10–16.ix.2009 (QSBG and NMWC).
A further 1♂ 70♀ tentatively identified as this species from: Doi Phu Kha National Park (Nan Province), Doi Inthanon, Doi Suthep and Doi Phahompok national parks (Chiang Mai Province), Kaeng Krachan National Park (Phetchaburi Province), Khao Kho National Park (Phetchabun Province) and a site in Mae Hong Son Province (QSBG, MHNG and NMWC).
Diagnosis. A predominantly black legged species with apex of hind femur sharply demarked dark yellowish orange above and below. Front and mid femora entirely black or narrowly and diffusely yellowish apically. Front and hind tibiae mostly black but mid tibia varying from entirely black to mostly yellow and with only short hairs ventrally apart from 1 very long bristle near middle. The antennal stylus is bare, the posterior coxa has black setae behind only at tip and there is no strong ventral bristle at the base of the mid metatarsus. In females, tergite 8 encircles the abdomen and sternite 8 is produced apically into two long narrow processes.
Description. Male: body length 4.0– 4.5 mm. Head subshining black; face dark reddish yellow, slightly darker laterally along eye margin and dorsally near antennal sockets; clypeus black. Antenna black, with postpedicel ovate in lateral view, 2.5 X long as wide; stylus bare, ~4–5 X long as postpedicel, black, vague discontinuity on distal~ 0.2 appearing whitish in some lights. Mouthparts blackish, palpus very narrow, fine hairs below not obviously longer than those at tip. Thorax with ground colour black, outer face of postpronotal lobe and postalar callus narrowly to broadly yellowish; scutum rather shining, with bluish reflections, very thinly dusted, more strongly so laterally and on prescutellar depression; pleura more strongly dusted than scutum. Posterior dc (in front of prescutellar depression) strong, dc and acr otherwise small, hair-like; pa and upper npl strong, lower npl weaker; 2 strong sct and several much smaller marginal hairs on scutellum. Legs with F 3 completely ringed yellow to orange on apical 0.05–0.1, sharply demarked from otherwise black limb; F 1 and F 2 black; F 2 sometimes and F 1 rarely narrowly and more diffusely yellow apically; tibiae predominantly black but in pale individuals T 3 narrowly yellowish at base and tip; T 2 sometimes yellow (vaguely darker at base and tip); front tarsi black, mid and posterior tarsi varying from clear yellow to black. Coxae with brownish or pale hairs becoming black behind C 3 apically. F 1 somewhat inflated, widest 0.3 from base, ventral hairs about middle as long as limb is deep; F 2 less inflated, slightly narrowed on distal 0.3, ventral hairs about middle as long as limb is deep, some shorter slightly stronger bristles anteriorly, especially about base. F 3 strongly and quite evenly inflated, widest 0.5–0.6 from base, rather evenly covered with distinct pale hairs; 4–7 fine bristles anteriorly; ventral spines consisting of 2 narrowly spaced rows of inconspicuous short spines with ~8 longer bristles (not as long as limb is deep) anteriorly; pv fringe of longer hairs becoming as long as limb is deep and blackish distally. T 1 with short dark hairs dorsally from which can be distinguished 1–2 rather stronger bristles medially; ventral hairs becoming longer distally where 0.4X long as limb; apical circlet of ~6–8 setae strongest dorsally. T 2 with strong bristles 5–6X long as limb is deep at 0.1–0.2 and 0.5 from base and ventrally at 0.7, often 1 shorter dorsal at 0.75; apical circlet of ~6 distinct bristles including one av almost as long as MT 2. T 3 lacking strong bristles, patch of yellowish pile posteroapically. MT 1 with 5–6 long hairs anteriorly and poteriorly, as long as segment basally, becoming shorter distally, continued and becoming shorter still on second tarsal segment. MT 2 without long ventral bristle at base, all setae rather short. MT 3 with short ventral spines and short yellowish pile posteriorly. Wing membrane clear or slightly tinged brown, veins yellowish brown; stigma distinct, long, reaching costa at ~ 0.7–0.8 distance between end of R 1 and R 2+3. Squama with pale fringes. Halter white, base of stem brownish. Abdomen subshining black, duller than thorax, tergites with faintly bronze reflections, lightly and uniformly pale dusted; bristly hairs pale, longest and more numerous laterally and marginally on tergites 1–4. Terminalia (Figs 9–16) mostly blackish, inner dorsal margin of epandrial lamellae irregularly concave; left epandrial lamella (Fig. 11) with short pointed dorsoapical process and similar process beneath. Surstyli rather variable; right surstylus (Figs 12, 16) broad basally, narrowing distally; left surstylus (Figs 11, 15) broad basally, variably narrow and somewhat hook-shaped distally. Hypandrium (Figs 13, 14) with undulating broad apex bearing very strong black bristles and long digitiform apical process bearing 2 or more fine long setae. Female: Similar to male but T 1 with shorter hairs ventrally and 1–2 distinct short bristles dorsally more clearly distinguished from surrounding hairs. Front tarsus without long hairs anteriorly and posteriorly on MT 1 and second segment. Abdomen with pale hairs at lateral margins of tergites shorter. Tergite 8 (Figs 17, 18) strongly sclerotized, encircling abdomen; tergite 10 weakly sclerotized, only faintly indicated. Sternite 8 black, subtriangular, produced apically into two narrow processes which are apically downcurved; sternite 10 with concave inner margin bearing numerous short stout setulae. Cercus narrow, fine long hairs on dorsal and lateral margins.
Comment. Hybos ancistroides was described from 1♂ and 4♀ captured in Guangxi, China (Yang & Yang 1986) and appears to be quite widespread in China occurring in the Wuling, Quinling and East China mountains. It is broadly distributed throughout Thailand (Fig. 243) but has yet to be found on the Isaan Plateau. The type material was reported to have predominantly black femora and tibia but examination of the more numerous material from Thailand reported here has revealed considerable variation in leg colour, especially of the mid tibia which varies from black to yellow. Chinese material also apparently differs from Thailand examples in lacking long bristles on the apex of the hypandrium. Hybos ancistroides is most likely to be confused with H. particularis Yang, Yang & Hu, 2002, H. men sp. nov. or possibly with H. longshengensis Yang & Yang, 1986. These four species have the posterior femora yellow apically but in H. particularis and H. men sp. nov. the mid and front femora are also distinctly tipped yellowish whereas in H. ancistroides and H. longshengensis they are blackish or, at most, narrowly and diffusely tipped yellow. Males of H. men sp. nov. have at least a few long fine anteroventral hairs almost as long as the very strong bristle near the middle of the mid tibia and the apical processes on sternite 8 of the female are much shorter than in the other species. The mid tibia of H. ancistroides is usually blackish but its colour varies and can sometimes be yellow (approaching the condition found in H. longshengensis) but in such cases it is always rather diffusely darker, almost blackish at base and at apex. It is preferable to confirm determinations of all four species by examination of the male terminalia. Certain females of H. particularis and H. ancistroides may not be possible to identify.
The type locality of H. ancistroides in China was at 720 m (Yang & Yang 1986) but in Thailand it has been found at elevations between 550–2,200 m with most (93% of 89 known specimens) occurring in predominantly evergreen forest types at mid elevations from 900–1,700 m. Thus H. ancistroides appears to be ecologically isolated from its undoubtedly closely related congener H. particularis which is largely confined to dryer forest types below 750 m. Although data for H. particularis are sparse, adult numbers probably peak between December and March and again in June and July whereas H. ancistrodes peak abundance occurs between September and December (Fig. 284). Females were more abundant in the samples (ratio of ♂: ♀ = 0.1)
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 12-13, DOI: 10.11646/zootaxa.3690.1.1, http://zenodo.org/record/6329811