Hemerodromia aliaexstriata, 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 : 551-552

Hemerodromia aliaexstriata sp. nov.

( Figs 1–2 , 12 )

Diagnosis. A predominantly orange yellow species with a dark median stripe on the scutum becoming wider posteriorly, a yellow scutellum and with dark marks between the front coxae and on the katepisternum. The male cercus is broad in lateral view with bluntly pointed dorsoapical and ventroapical processes and the epandrium is narrow and elongate, extending beyond the tip of the cercus.

Description. Male: body length 2.6 mm; wing length 2.0 mm. Head. Rather elongate, ~1.5X long as wide; upper occiput slightly bulging, making smooth angle where meeting vertex. Black with paler dusting. Antenna and mouthparts whitish. One pair of minute reclinate ocellar setulae; 3–4 pairs of minute vertical setulae only about as long as ocellars. Antenna with postpedicel ~1.8–2.0X long as wide, stylus somewhat shorter. Thorax. Not quadrate anteriorly; anterior margin of scutum gradually curving in lateral view. Ground colour orange yellow; scutum with median brownish black stripe, narrow anteriorly, becoming as wide as base of scutellum posteriorly; mediotergite broadly darkened medially; strong black mark between insertion points of front coxae and another smaller oblique mark on katepisternum; small dark marks also present immediately in front of base of wing, obliquely about prothoracic spiracle and on sutures of laterotergite. All setae whitish yellow, minute; notopleural setulae present but very small, scutellars apparently absent. Legs. Yellowish, distal tarsal segments somewhat darkened. C1~1.1X long as distance between base of C1 and C2. F1 hardly longer than C1, ~4.0X long as wide, strongly and evenly inflated, slightly constricted on proximal 0.2; femoral formula ~ 6–8/22–25/21–24/5–6, denticles black, rows converging apically; spines yellow except 1–2 near base black. T1 ~ 0.7X long as F1; evenly curved, ventral face shallowly concave, with 2 rows of ~20 sharply pointed spinose setae ventrally; ventroapical spur weakly developed; distinct ventroapical erect black spinose seta present. Mid and hind legs slender with only small setulae. Wing. Membrane darkened by greyish microtrichia on distal 0.9, paler about base of wing. Veins greyish black, R 4+5 darker still. Veins C and R 1 yellowish at extreme base. Marginal setulae dark. R 2+3 almost linear, joining C ~0.8–0.9X distance between ends of R 1 and R 4. Length of C between ends of R 2+3 and R 4 about as long as R 4. R 4 slightly S-shaped. R 5 ~ 2.0X long as R 4, almost linear. R 4+5 fork distal to M 1+2 fork by ~ 1.3X length of R 4. M 1 almost linear, slightly convergent with R 5, becoming parallel at extreme tip. Cell bm+dm short, ending at tip of R 1. Halter yellowish white. Abdomen. Black dorsally, paler ventrally, tergites 1 and 2 yellowish. Terminalia. Black with dark setae. Cercus ( Figs 1–2 ) short, not extending beyond tip of epandrium; rather broad in lateral view with short bluntly pointed dorsoapical process and longer ventroapical process; outer surface with fine black hairs. Epandrium long and narrow with fine black hairs ( Fig. 1 ). Hypandrium small, strongly arched, bare. Phallus with pair of apical hook-like processes. Female: similar to male but scutum with median stripe somewhat narrower anteriorly and abdomen yellowish ventrally. Tip of abdomen truncate, terminalia rather short, hardly extensible and not at all ovipositor-like.

Type material. HOLOTYPE ♂: THAILAND, Mae Hong Son Province, river near Susa waterfall, 306 m, 19.47797°N, 98.12089°E, 3.iv.2019, netted A. R. Plant ( QSBG) . PARATYPES: 2♀, same data as holotype ( QSBG) ; 1♂, 3♀, Mae Hong Son Province, Susa waterfall, tufa cliff at confluence of tufa str. and river, 305 m, 19.47457°N, 98.12421°E, 3.iv.2019, netted A. R . Plant ( QSBG) .

Etymology. The specific epithet is a concatenation of the Latin alia ex meaning ‘different from’ and striata in reference to this species not being identical with H. striata Yang & Yang. It is used as a noun in apposition.

Remarks. The markings on the scutum of this species somewhat resemble those of H. acutata Grootaert, Yang & Saigusa (in which the width and intensity of the median dark stripe varies greatly) or even H. systoechon Plant (in which the dark scutal marking is usually very broad with diffuse edges) from which it may readily be separated by the male terminalia. A generally similarly broad cercus with bluntly pointed dorsoapical and ventroapical processes suggests close affinities with two extralimital species, H. oratoria (Fallén) (Holarctic distribution), and H. striata Yang & Yang from the eastern Palaearctic ( China, Beijing). The latter species also has an elongate epandrium. Hemerodromia aliaexstriata sp. nov. is known from a calcareous river in the extreme northwest of Thailand ( Fig. 12 ).

Figures

FIGURES 1–2. Male terminalia of Hemerodromia aliaextriata sp. nov. 1, lateral view of terminalia; 2, dorsal view of cerci. Abbreviations: cer=cerci, epa=epandrium, hyp=hypandrium.

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.