Hemerodromia pairoti, Plant, 2020

Plant, Adrian R., 2020, New species of Hemerodromia Meigen (Diptera: Empididae: Hemerodromiinae) associated with limestone karstic waters in Thailand, Zootaxa 4758 (3), pp. 549-560 : 555

Hemerodromia pairoti sp. nov.

( Figs 8–9 , 15 )

Diagnosis. A yellowish species obscurely darkened on scutum medially and on scutellum and mediotergite. Best recognised by characters of the male terminalia, with cercus dilated apically and surstylus apically L-shaped.

Description. Male: body length 2.4 mm; wing length 2.0 mm. Head. Slightly elongate. 1.4X long as deep, upper occiput making smooth curve where meeting vertex, hardly bulging. Black with paler dusting. Antenna and mouthparts whitish. One pair of minute reclinate ocellar setulae; ~ 3 pairs of smaller verticals. Antenna with postpedicel ~ 2.5–3.0X long as wide, stylus of similar length. Thorax. Yellow; scutum with vaguely darkened broad median stripe, at centre of which is much narrower and somewhat darker median stripe; scutellum and mediotergite brownish; small dark marks ventrally between insertion points of front coxae, obliquely about anterior spiracle, immediately in front of base of wing and in sutures of laterotergite. All setae yellowish, minute; notopleural very small; scutellum with pair of minute hairs on disc. Legs. Whitish yellow, distal tarsal segments hardly darker. C1 ~1.2X longer than distance between base of C1 and C2. C1, C2 and C3 all with minute setulae. F1 ~1.1X long as C1, ~ 5X long as wide, slightly constricted on ventral face 0.2 from base; with two parallel rows of ~16 minute black denticles ventrally, either side of which is linear series of ~5–6 inconspicuous fine yellow bristles, noticeably stronger around 0.2 from base. T1 ~0.75X long as F1, slightly curved, ventral face shallowly concave bearing two rows of ~ 20 minute, sharply pointed, blackish spinose setulae; ventroapical spur weakly developed; distinct ventroapical erect black spinose seta present. Wing. Membrane darkened by greyish microtrichia on distal 0.9, paler at base. Veins greyish, paler at extreme base. R 2+3 linear, joining C ~ 0.7–0.8X distance between ends of R 1 and R 4. Length of C between ends of R 2+3 and R 4 ~1.2–1.4X long as R 4. R 4 linear, hardly S-shaped, angle with R 5 at extreme base ~ 75°. R 5 ~2.2X long as R 4. R 4+5 fork distal to M 1+2 fork by ~1.5X length of R 4. R 5 and M 1 almost linear, slightly but distinctly convergent distally. Cell bm+dm ending just beyond end of R 1. Halter yellowish white. Abdomen. Black, paler basally, especially on sternites 1–3. All setulae small and dark, becoming slightly longer on posterior margins of distal segments. Terminalia black. Cercus ( Figs 8–9 ) elongate, extending slightly beyond tip of epandrium, conspicuously expanded dorsoapically ( Fig. 8 ); with numerous distinct setae. Epandrium ( Fig. 8 ) bluntly pointed apically, with some moderately strong bristles apically. Surstylus present, extending distinctly beyond tip of epandrium, broadly L-shaped distally. Hypandrium pointed apically, with fine tomentum and few distinct bristles. Phallus not examined. Female: similar to male but scutum with broad median stripe more clearly defined. T1 with ventroapical setae rather longer. Abdomen with sternites 2–5 more distinctly yellowish; terminalia not elongate, not ovipositor-like.

Type material. HOLOTYPE ♂: THAILAND, Mae Hong Son Province, Ban Muang Phaeum, Phaeum River , 649 m, 19.5854°N, 98.30049°E, 4.iv.2019, netted A. R. Plant ( QSBG) . PARATYPES: 1♀, same data as holotype .

Etymology. The specific epithet honours Pairot Pramual in recognition of consistent support for my explorations of Thailand’s Empididae fauna.

Remarks. The yellowish thorax with variably dark median stripe on the scutum recalls H. systoechon or H. acutata. However the thoracic markings of these species (and very probably of this species) are very variable and identification must rely on examination of the male terminalia. The male cercus is greatly dilated apically resembling that of H. songsee Plant, which has a very distinctive black and yellow pattern on the thorax, quite unlike the new species. A generally similar L-shaped apex of the surstylus occurs in other southeast Asian species (e.g., H. attenuata, H. furcata, H. yunnanensis, H. digitata, H. oretenebraea sp. nov. and H. samoha sp. nov.). Hemerodromia pairoti sp. nov. is known only from a calcareous river in the extreme northwest of Thailand ( Fig. 15 ).

Figures

FIGURES 8–9. Male terminalia of Hemerodromia pairoti sp. nov. 8, lateral view of terminalia; 9, dorsal view of cerci. Abbreviations: cer=cerci, epa=epandrium, hyp=hypandrium, sur=surstylus.

FIGURES 12–16. Distribution of five new species of Hemerodromia in Thailand at a resolution of 0.25° and symbols sized at 0.25° of latitude and longitude. Occurrence of limestone karst landforms is indicated by grey shading. 12, Hemerodromia aliaextriata sp. nov.; 13, Hemerodromia deprimatura sp. nov.; 14, Hemerodromia oretenebraea sp. nov.; 15, Hemerodromia pairoti sp. nov.; 16, Hemerodromia samoha sp. nov.