Hybos aceriformis, PLANT, 2013

PLANT, ADRIAN R., 2013, <p class = " HeadingRunIn " align = " left "> <strong> The genus <em> Hybos </ em> Meigen (Diptera: Empidoidea: Hybotidae) in Thailand </ strong> </ p>, Zootaxa 3690 (1), pp. 1-98 : 11-12

Hybos aceriformis sp. nov.

( Figs 5–8, 242, 283)

Type material. HOLOTYPE ♂: THAILAND, Chaiyaphum Province, Pa Hin Ngam National Park, Ecotone between mixed deciduous/dry dipterocarp, 15°38.1'N, 101°23.857'E, 700m, 5–11.viii.2006, Malaise trap, Katae Sa-nog & Buakaw Adnafai [ T440 ]( QSBG) . PARATYPES: 8♂, 9♀, same data as holotype, 5–11.viii.2006, 11– 18.viii.2006, 18–24.viii.2006, 24–30.viii.2006 ; 6♂, 2♀, creek at Tung Dok Grajeaw , 15°38.391'N, 101°23.609'E, 750 m, 6–12.vii.2006, 12–18.vii.2006, 19–24.vii.2006, 24–30.vii.2006 ; 3♂, 6♀, car park at Tung Dok Grajeaw , 15°38.438'N, 101°23.576'E, 780 m, 12–18.vii.2006, 24–30.vii.2006 ; 1♂, Dry dipterocarp forest, 15°38.099'N, 101°23.921'E, 698 m, 11–18.viii.2006 : 7♂, Loei Province, Phu Ruea National Park, Nern Wibaak ditch, 17°29.907'N, 101°20.483'E, 1196 m, 5–12.viii.2006, 12–19.viii.2006, 26.viii–2.ix.2006 ; 1♂, Pan Hin Khan Maak ditch, 17°30.042'N, 101°20.474'E, 1219 m, 12–19.viii.2006 ; 2♂, Huay Taey ditch, 17°30.128'N, 101°20.339'E, 1233 m, 19–26.viii.2006 ; 1♀, Subhnonghin , 17°28.772'N, 101°21.308'E, 860 m, 19–26.vii.2006 ; 7♂, 5♀, Office , 17°28.826'N 101°21.33'E, 860 m, 19–26.vii.2006, 26.vii.-2.viii.2006 ( NMWC, QSBG) .

Etymology. Named in recognition of the shape of sternite 8 in the female which resembles the seed of the tree genus Acer .

Diagnosis. A species with thorax black and legs mostly yellow excluding the tip and often dorsum of the hind femur. The hind femur is strongly spinose in males, much less so in females and the mid tibia has two strong dorsal setae. The antennal stylus is distinctly subplumose and the abdomen is entirely black

Description. Male: length 3.5mm. Head subshining black; face yellowish brown medially. Postocular setae black, hairs on lower occiput mostly pale. Antenna black, postpedicel ovate in lateral view, ~2.5–3 X long as wide; stylus ~6X long as postpedicel, black, distinctly subplumose with lateral hairs ~2X longer than stylus is deep, bare and narrower on distal 0.15–2. Mouthparts brownish black, palpus very narrow with distinct fine seta near tip. Thorax with ground colour black, postpronotal lobes narrowly whitish anteroapically. Scutum lightly dusted, subshining on disc; prescutellar area and lateral margins in notopleural area more thickly dusted grey; acr 3–4- serial, dc uniserial; posterior dc and acr in front of prescutellar depression strong; 2 npl, 1 pa and 2 sct strong. Legs yellow with distal tarsal segments dusky, T 1 and coxae sometimes somewhat darker; F 3 with apical 0.2 blackish, and often somewhat darkened dorsally throughout. Coxae with pale hairs, legs otherwise with stronger setae black. F 1 with ventral hairs short, hardly longer than limb is deep. F 2 slightly distorted, weakly concave in front about 0.3 from base, ventral fringe very short. F 3 moderately inflated, widest 0.6–0.7 from base: viewed laterally lower margin almost linear, upper margin convex; ventral spines comprising 25–32 long bristles (mostly as long or longer than limb is deep) arranged in 2 rows near base, sometimes becoming ~3-serial at middle and uniserial apically where shorter; pv fringe of 2–5 black bristles on distal 0.3, becoming pale and finer on proximal 0.7; 3–4 distinct somewhat curved anterior proclinate bristles on distal 0.5. T 1 with distinct bristle dorsally at 0.6 from base; apical circlet weakly developed excepting 1 stronger ad bristle. T 2 with strong bristles 0.5–0.6X long as limb dorsally at ~0.2 and 0.5 from base and ventrally at 0.6; apical circlet strong with one av ~0.8X long as MT 2. T 3 slightly inflated distally (1.2–1.5X wide at tip compared with base), 1 distinct bristle dorsally at 0.6; 3 distinct apical setae. MT 1 and especially MT 2 with distinct ventrobasal bristle. MT 1 with fine hairs ventrally becoming shorter distally. MT 2 with fine bristle ventrally at 0.5 (smaller than ventrobasal but obviously distinct from other ventral hairs and as long as dorsal and anterior bristles in apical circlet). MT 3 with spinose setae admixed with finer hairs ventrally. Wing membrane faintly tinged brown, veins yellowish brown; stigma distinct, greyish brown, reaching costa at ~0.9 distance between end of R 1 and R 2+3. Squama with pale hairs. Halter white. Abdomen subshining black, tergites strongly dusted greyish, sternites more shining. Tergites with long yellowish bristles on posterior margins laterally, becoming shorter on distal segments; sternites with long pale hairs, hardly shorter on distal segments, somewhat brownish on sternite 7 posteriorly. Terminalia rather shining black ( Figs 5–7) globoid, with mostly black setae; left epandrial lamella with slight projections from upper and lower margins apically; left surstylus bluntly pointed; right surstylus ( Fig. 7) with apical part rather long, bluntly pointed. Hypandrium ( Fig. 6) narrowed apically, with tip blunt, curving inwardly; shorter process subapically also incurved. Female similar to male but contrast between yellow and dark parts of legs stronger, especially on F 3 which usually is not darkened dorsally. MT 1 with ventral hairs shorter, MT 2 lacking distinct bristle ventrally at 0.5 and apical circlet weaker. F 3 more slender, slightly petiolate proximally, widest ~0.8 from base; only 8–10 bristles ventrally, entirely uniserial, 1–2X long as limb is deep on proximal 0.8, shorter distally; pv fringe of fine hairs weaker, at most 1–2 dark bristles near tip. Abdomen subshining black with shorter setae on posterior margins of tergites. Terminalia ( Fig. 8) more shining black, setae blackish; sternite 8 slightly protuberant, central more or less circular area covered with small fine hairs and with bare lateral lobes, somewhat broader apically (extent of sclerotization variable, sometimes space between lobes more strongly sclerotized than indicated in Fig. 8 when shape of sternite difficult to discern.

Comment. The leg colour of H. aceriformis sp. nov. varies somewhat and in exceptionally dark males approaches the condition found in H. divisus sp. nov. (with which it is probably closely related). However, in such cases the morphology of the male terminalia and other characters given in the descriptions readily distinguish between the two species. Hybos aceriformis sp. nov. is known only from eastern Thailand where it has been found on the Petchabun and Dong Paya Yen mountains bordering the western margins of the Isaan Plateau ( Fig. 242). The species has been found in strongly seasonally arid forest biotopes between 700–1,233 m and adult emergence is confined to July and August at the height of the wet season ( Fig. 283).