Hemerodromia yunnanensis Yang & Yang

Plant, Adrian R., 2015, Diversity of Hemerodromia Meigen, 1822 (Diptera: Empididae) in Thailand, the tip of a tropical iceberg?, Zootaxa 4039 (1), pp. 1-56 : 44-46

Hemerodromia yunnanensis Yang & Yang

( Figs 68–70 , 96 )

Hemerodromia yunnanensis Yang & Yang, 1988: 283 .

Diagnosis. A species with thorax black, legs and antennae variably blackish to yellowish. Front femur often blackish. The male terminalia are distinctive in having cercus narrow, epandrium bluntly pointed ovoid and surstylus large, extending beyond tip of epandrium, conspicuously inflated and broadly L-shaped apically.

Re-description. Male: Body length 2.3 mm; wing length 2.0 mm. Head. Black, dusted brownish grey, strongest on upper occiput and vertex. Antenna sometimes entirely pale but usually with scape and pedicel pale brown, postpedicel paler; stylus blackish. Mouthparts yellowish white with tip of proboscis brownish. One pair reclinate ocl; two pairs small vtl distinguishable from smaller fine hairs on vertex and upper occiput; postocular and lower occipital setulae minute. Antenna with postpedicel ~ 2X long as wide, stylus rather shorter; scape with distinct fine dorsal seta. Thorax. Black, dusted greyish. All setae yellowish; minute apart from one npl; sct absent but scutellum with a pair of very small erect setulae on disc. Legs. Variable ground colour; generally brownish yellow with C2, C3 and C1 basally whitish (C1 occasionally blackish distally) and F1 blackish anteriorly and posteriorly (sometimes only vaguely so). C1 ~ 1.2X longer than distance between C1 and C2, all setulae minute except a few slightly longer dorsoapicals. C2 and C3 with a few fine setulae anteriorly and C3 with distinct yellowish dorsoapical. F1 ~ 1.0–1.1X long as C1, ~ 4– 5 X long as wide, not at all constricted 0.3 from base; femoral formula ~ 8– 11 /18–19/17–19+0–1/7–8, denticles black, rows converging apically; spines yellow, short, fine much shorter than limb is deep longest basally, basal spine of pv row longer. T1 ~ 0.7X long as F1, evenly curved, ventral face shallowly concave; with 2 rows of ~19 sharply pointed spinose setae ventrally; ventroapical spur hardly developed; a strong ventroapical apical erect black spinose seta present. Mid and hind legs slender with only small setulae. Wing. Membrane conspicuously darkened with black microtrichia but hyaline basally. Veins blackish but whitish near base. Marginal setulae greyish. R2+3 linear, joining C ~ 0.7X distance between end of R1 and R4; length of C between ends of R2+3 and R4 ~1.1–1.2X long as R4. R4 almost linear, only slightly S-shaped, angle with R5 at extreme base ~ 70–80°, slightly swollen apically before junction with C; R5 ~2.2X long as R4; R4+5 fork distal to M1+2 fork by ~ 1.2X length of R4; R5 and M1 almost linear, convergent distally; cell bm+dm short, ending at level of R1. Halter variably blackish, somewhat paler dorsally and on stem; sometimes entirely dirty white. Abdomen.

Black dusted greyish but sternite 1 with at least proximal 0.5 whitish, sternite 2 whitish with dark median line and posterolateral marks; all setulae small except posteriorly and laterally on sternite 7. Terminalia. Black with dark setae. Cercus elongate ( Figs 68, 69 ), extending well beyond apex of epandrium; narrow in lateral view; distinctly setose dorsally. Epandrium bluntly pointed ovoid, with strong setae distally. Hypandrium, with strong setae posteroventrally. Surstylus present, extending beyond tip of epandrium, conspicuously inflated apically where broadly L-shaped with close set minute black setulae in inner face. An elongate apically hook-shaped process (possibly lower lobe of surstylus) emerging just beyond tip of epandrium ( Fig. 70 ). Female: Similar to male but F1 with femoral formula 7– 9 /16–17/14–18+1/10; basal spine of pv row much stronger, at least as long as limb is deep. Abdomen with less conspicuous setae distally but tergite 7 blackish and sternite 7 brown.

Material examined. 179♂, 99♀, Beung Kan, Chaiyaphum, Chantaburi, Loei, Nan, Phayao and Surat Thani provinces ( QSBG & NMWC); 1♂ removed for DNA sequence analysis ( INPA); 14 specimens removed for population genetics studies ( MSU).

Remarks. There is considerable variation in the colour of the antenna, legs and halter in H. yunnanensis . In particular both front femur and halter vary from yellowish to deep black. In Thailand this species is most similar to H. fusca Yang & Yang, 1986 and H. phahompokensis sp. nov. from which it may be distinguished most readily by the shape of the cercus and surstylus. Hemerodromia yunnanensis is clearly closely related to H. serpa Smith, 1965 from Nepal which has similarly L-shaped surstylus but with black setulae on the outer face. In H. serpa the lower elongate process has two apical hook-like structures (only one in H. yunnanensis ). Hemerodromia yunnanensis was described from Yunnan, China ( Yang & Yang 1988). Its distribution in Thailand shows an eastern bias ( Fig. 96 ) where it is known from numerous localities in Loei and Chaiyaphun provinces in the Petchabun Mountains, Phayao and Nan provinces in the north, Sisaket Province in the Dong Rak range and from mountains along the west bank of the Mae Nam Kong river (Mekong) in Bueng Kan Province. It has also been found in the southeast and south in Chantaburi and Surat Thani provinces respectively. The species has been found at 51–1,152 m, mostly around streams and rivers in a variety of forest types but also in agricultural areas (rice fields). Adults are active during the cool dry season with 254 (91%) of 278 individuals being captured during October and November but small numbers have also been taken in January, May, July and September.

Figures

FIGURES 68 – 70. Male terminalia of Hemerodromia yunnanensis Yang & Ya ng. 68, lateral view of terminalia; 69, dorsal view of cerci; 70, apex of lower narrow process (lower lobe of surstylus?). Abbreviations: cer = cerci, epa = epandrium, hyp = hypandrium, sur = surstylus (upper lobe?).

FIGURES 91 – 98. Distribution of Hemerodromia spp. in Thailand at a resolution of 0.25 ° of latitude and longitude with symbols scaled to 0.5 °. 91, H. ocellata sp. nov.; 92, H. oriens sp. nov.; 93, H. phahompokensis sp. nov.; 94, H. songsee sp. nov.; 95, H. systoechon sp. nov.; 96, H. yunnanensis Yang & Yang; 97, H. zetalutea sp. nov.; 98, Species richness of Hemerodromia spp. in Thailand at a resolution of 1 ° with symbols plotted at same resolution.