Hemerodromia acutata Grootaert, Yang & Saigusa

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 : 6-8

Hemerodromia acutata Grootaert, Yang & Saigusa

( Figs 9, 10 , 73 )

Hemerodromia acutata Grootaert, Yang & Saigusa, 2000: 73 .

Diagnosis. Thorax yellow with broad dark median stripe on scutum; scutellum yellowish behind and metatergite black. Prothoracic ‘collar’ with dorsal surface yellow, black only very narrowly at middle. Cell bm+dm short, ending at about level of R1. Male terminalia with cerci and epandrium narrow; surstylus narrow with tip down curved, somewhat club-shaped, extending just beyond tip of epandrium.

Re-description. Male: Body length 2.8–2.9 mm; wing length 2.2–2.3 mm. Head. Black, dusted greyish; antenna and mouthparts pale whitish yellow, all setae pale; one pair reclinate ocl; postocular setae uniseriate, merging above with 1–2 pairs small vtl and several fine setulae on vertex; frontal setulae apparently absent. Antenna with postpedicel 1.5–2.0X long as wide, stylus of similar length; scape with distinct fine dorsal seta. Thorax. Dusted greyish. Scutum with ground colour yellow; a broad black or brownish median stripe, very broad posteriorly, narrowing to 0.3X as wide anteriorly; sometimes with indications of two darker lateral stripes posteriorly within median stripe, broader and widely spaced posteriorly becoming somewhat narrower and converging anteriorly. Prothoracic ‘collar’ yellow with narrow black median dorsal mark. Scutellum yellowish, at least broadly on posterior margin; often with darker area anteriorly, contiguous with and forming slight posterior extension of dark medium stripe on scutum. Mediotergite black or brownish. Pleura yellow; sutures about laterotergite and base of halter blackish. All setae yellowish; minute apart from pair of distinct sct and one smaller npl. Legs. Whitish yellow with apical tarsal segments hardly darkened. C1 rather short ~ 1.1–1.2X longer than distance between C1 and C2, all setulae minute excepting a few slightly longer apicals. F1 ~ 1.2–1.3X long as C1, ~ 5X long as wide, evenly inflated, hardly constricted on proximal 0.2–0.3; femoral formula ~ 6/14/16 +0–1/6–7, denticles black, rows converging apically; spines yellow, pv and av rows similarly long, becoming somewhat longer proximally. T1 ~ 0.7X long as F1, evenly curved, ventral face shallowly concave; with one row of ~ 15 sharply pointed spinose setae ventrally; a very small ventroapical spur with strong erect ventroapical black spinose seta arising from near base. Mid and hind legs slender with only small predominantly pale setulae but mid metatarsus with somewhat longer setulae ventrally, T3 with short row of small setae posterodorsally and ‘comb’ of short setae posteroapically. Wing. Membrane slightly darkened by rather even covering of greyish brown microtrichia but hyaline basally. Veins greyish yellow to blackish but whitish near base; R2+3 and R4+5 often darker basally; C pale yellow with posterior margin very narrowly black. Marginal setulae pale. R2+3 linear before tip, rather long joining C ~ 0.7–0.8X distance between end of R1 and R4; length of C between ends of R2+3 and R4 short, ~1.0–1.2X long as R4. R4 slightly S-shaped, angle with R5 at extreme base ~ 80°, becoming ~70–80° thereafter, joining C at ~ 80–90°; R5 ~ 2X long as R4, almost linear; R4+5 fork distal to M1+2 fork by ~ 1.5X length of R4. M1 almost linear beyond base, evenly convergent distally with R5; cell bm+dm short, ending at about level of R1. Halter yellowish white. Abdomen. Yellow with tergites 1, 6 and 8 posteriorly black. Lacking strong setae except blackish bristles on posterior margin of tergite 8 and yellowish bristles on sternites 8. Terminalia. Deep black with dark setae. Cerci ( Figs 9, 10 ) elongate, extending beyond tip of epandrium; slightly dorsoventrally flattened apically with some short small strong setae on inner face. Epandrium narrowed distally ( Fig. 9 ). Hypandrium rather quadrate apically with cluster of strong setae ventroapically. Surstylus present, narrow, elongate; tip inflated, somewhat club-shaped, slightly down curved, extending just beyond tip of epandrium. Female: similar to male but spines and denticles beneath F1 rather more numerous, femoral formula ~ 6– 7 /18–19/19+1/6–7. Abdomen yellow with tergites 2–5 and 6 on posterior margin black. Terminalia black.

Material examined. 2♂, 1♀, THAILAND: Chiang Mai Province, Doi Inthanon NP, Siriphum w/f, 1,333 m, 18.5422°N, 98.5172°E, 23.xi.2012, 14.i.–3.iii.2014, netted and MT, A.R. Plant & W. Srisuka; 1♀, small stream in hill evergreen below checkpoint 2, 1,650 m, 18.516°N, 98.483°E, 6.x 11.2013, netted, A.R. Plant; 1♀, Check point 2 trap 1, 1,639 m, 18°31'39.5"N, 98°29'59.7"E, 14.i.–3.iii.2014, MT, W. Srisuka; 1♂, Summit trap1 (back of office), 2,534 m, 18°35'12.8"N, 98°29'14.2"E, 30.vii.–27.viii.2014, MT, W. Srisuka; 11♂, 8♀, Kamphaeng Phet Province, Mae Wong NP, Chong Yen, 1,306 m, 16°5.212'N, 99°6.576'E, 10–17.ix.2007, 17–24.ix.2007, 24.ix.– 1.x.2007, 17–24.xii.2007, MT, C. Piluek & A. Inpuang ( QSBG & NMWC).

One ♂ from Chong Yen, 24.ix.–1.x.2007 selected for DNA sequence analysis ( INPA).

Remarks. This species was described from two males collected in Yunnan, China ( Grootaert et al. 2000) which were described as having “mesonotum with 2 blackish middle longitudinal stripes”. In specimens from Thailand, these two stripes are usually present but are superimposed upon and largely masked by a much broader blackish median stripe. However the male terminalia of Thai specimens match closely with the Chinese specimens ( Grootaert et al. 2000, figs 4, 5) and there can be little doubt that Thailand material is correctly assigned to H. acutata . As with many other species of Hemerodromia , thoracic colour pattern is variable and in some Thailand specimens of H. acutata , the blackish median stripe is distinctly abbreviated anteriorly, fading out before the front margin of the scutum. The colour of the scutellum is also very variable and while it usually has a distinctly yellow posterior margin, can be almost entirely blackish. The thoracic colour pattern of H. acutata often approaches that of H. systoechon sp. nov., especially when the scutellum is dark. Males of the two species may readily be distinguished by their terminalia. For distinguishing characters of females, see notes under H. systoechon sp. nov. Hemerodromia acutata is also known from Himachal Pradesh in northwest India ( Wagner et al. 2004) so its range is clearly large and its occurrence in Thailand is unsurprising. In Thailand the species has been found in the northern provinces of Kamphaeng Phet and Chiang Mai ( Fig. 73 ) with 24 (88%) of a total of 27 specimens being taken from September to December coincident with the end of the Southwest Monsoon and with the cool dry season. It inhabits evergreen forest biotopes but is especially prevalent in hill evergreen forest.

FIGURES 1–5. Morphology of Hemerodromia spp. 1–2. H. flaviventris Ya ng & Yang. 1, ♂ habitus; 2, ♂ front leg (coxa not shown); 3–5. H. anomala sp. nov. 3, ♂ habitus; 4, apex of wing; 5, Head and anterior part of thorax. Veins M1, M2 and R4 indicated.

Figures

FIGURES 9 – 10. Male terminalia of Hemerodromia acutata Grootaert, Yang & Saigusa. 9, lateral view of terminalia; 10, dorsal view of cerci. Abbreviations: cer = cerci, epa = epandrium, hyp = hypandrium, pha = phallus.

FIGURES 73 – 81. Distribution of Hemerodromia spp. in Thailand at a resolution of 0.25 ° and symbols sized to 0.5 ° of latitude and longitude. 73, H. acutata Grootaert, Yang & Saigusa; 74, H. alphalutea sp. nov.; 75, H. anisoserrata sp. nov.; 76, H. anomala sp. nov.; 77, H. attenuata sp. nov.; 78, H. betalutea sp. nov.; 79, H. conspecta sp. nov.; 80, H. deltalutea sp. nov.; 81, H. deminuta sp. nov.