Hybos vietnamensis, Huo, Shan, Grootaert, Patrick & Yang, Ding, 2010

Huo, Shan, Grootaert, Patrick & Yang, Ding, 2010, Two new yellow-legged species of the genus Hybos from Vietnam (Diptera: Empidoidea: Hybotinae), Zootaxa 2512, pp. 47-55 : 49-54

4. Hybos vietnamensis sp. nov.

( Figs. 4–6 , 11–14 )

Diagnosis. Arista short pubescent. Legs (including coxae and trochanters) yellow to brownish yellow except tarsomeres 3–5 blackish. Wing nearly hyaline. Hind tibia with 1 long ad seta near middle in male. Description. Male. Body length 4.2–4.3 mm, wing length 3.9–4.4 mm.

Head black, pale gray pollinose. Eyes contiguous on frons, dark yellow, and with distinctly enlarged upper facets. Setae and setulae on head black; ocellar tubercle weak, with one pair of short oc and 2 very short posterior setulae. Antenna black; scape bare; pedicel with circle of subapical setulae; first flagellomere without dorsal setulae; arista black, pubescent except apical 1/4 thin and bare. Proboscis blackish; palpus blackish with 1 setula at extreme tip.

Thorax black, pale grey pollinose. Setae and setulae on thorax black; h absent, 2 npl (posterior npl slightly longer than anterior one), acr in about 4 more or less regular rows, 1 long strong posterior dc and 5–6 setulae anteriad, 1 distinct presc, 1 long psa; scutellum with 6 short marginal setulae and 2 long subapical setae. Legs (including coxae and trochanters) yellow to brownish yellow except tarsomeres 3–5 blackish. Setulae on legs blackish, setae black, except coxae and trochanters with setulae and setae mostly pale. Fore femur 1.1 X and hind femur 2.0 X as wide as mid femur. Fore tibia with row of pv setulae nearly as long as femur thickness; mid femur with row of pv setulae shorter than femur thickness. Hind femur ( Fig. 5 ) with 4 preapical anterior setae, and with nearly four rows of ventral setae (6–8 av mostly as long as femur thickness). Fore tibia with 1 long ad seta near middle, apically with 1 long ad, 1 short av and 1 short pv seta. Mid tibia with 1 very long ad, 1 short ad and 1 very long av seta at middle, apically with 6 setae (1 pd and 1 av very long). Hind tibia ( Fig. 5 ) with 1 long ad seta near middle, apically with 1 av and 1 pd seta. Fore tarsomere 1 with 1 long ventral seta at base; mid tarsomere 1 with 1 long ventral seta at base and 1 short pv seta near base; hind tarsomere 1 with short ventral spine-like setae. Wing ( Fig. 4 ) nearly hyaline; stigma dark brown; veins dark brown, R4+5 and M1 slightly divergent apically. Squama dark yellow, bordered with pale setulae. Halter yellow.

Abdomen black, grey pollinose. Setulae and setae on abdomen brownish yellow or blackish. Male genitalia ( Figs. 11–14 ): left epandrial lobe rather wide with weakly concave inner margin; left surstylus finger-like, strongly curved inward and with a very short process at base; right epandrial lobe slightly narrower than left epandrial lobe, with distinct inner process near base; right surstylus basally rather wide and with very short apical process; hypandrium much longer than wide, apically very narrow, and lacking long setae.

Female. Body length 3.4 mm, wing length 3.4 mm. Similar to male, but differs in following points: Hind femur narrower, 1.8 X as wide as mid femur. Hind femur ( Fig. 6 ) without preapical anterior seta, and with row of 8 sparse av setae (only 2 basal av distinctly longer than femur thickness) and 1–2 very short pv setae at base. Fore tibia with 1 long ad seta at middle, apically with 1 very long ad and 1 short pv seta. Mid tibia with 1 very long ad seta near base and 1 very long av seta at middle, apically with 5 setae (1 av very long). Hind tibia ( Fig. 6 ) with (or without) 1 long ad seta at middle, apically with 1 av and 1 pd seta.

Type material. Holotype male, VIETNAM: Lam Dong, Bidoup Nuiba nr. Dalat, 1650–1700 m, Malaise trap 1–12, Rain forest & Pinus , 12–15.X.2005, leg. C. van Achterberg & R. de Vries. Paratypes: 1 male, 1 female, same data as holotype.

Distribution. Oriental Region: Viet Nam (Lam Dong).

Etymology. The specific name refers to the type locality in which the type locality is situated.

Remarks. This new species is somewhat similar to Hybos medialis sp. nov. in the shape of the hypandrium, but it may be easily separated from the latter by the arista pubescent on basal 3/4, coxae and trochanters yellow and hind femur not dark medially, and wing not dark brown at apex of the basal cells and anal cell.

Figures

FIGURES 4 – 6. Hybos vietnamensis sp. nov. 4. Male wing. 5. Male hind leg, anterior view. 6. Female hind leg, anterior view. Scale bar = 0.6 mm.

FIGURES 11 – 14. Hybos vietnamensis sp. nov., male. 11. Genitalia. 12. Right surstylus. 13. Left surstylus. 14. Hypandrium. Scale bar = 0.5 mm.