Hemerodromia samoha, 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 : 556-557

Hemerodromia samoha sp. nov.

( Figs 10–11 , 16 )

Diagnosis. A species with brownish or yellowish thorax with wing membrane and veins mostly dark. The cercus is elongate and crenulated dorsally with numerous long bristles and the upper lobe of the surstylus is distinctly Lshaped.

Description. Male: body length 2.2 mm; wing length 1.7 mm. Head. Rather elongate. 1.6–1.8X long as deep; upper occiput rather linear in lateral view making smooth curve where meeting vertex, not bulging. Black dusted greyish, antenna and mouthparts pale whitish yellow. One pair of minute reclinate ocellar setulae; 3–4 pairs of vertical setulae. Antenna with postpedicel ~2.5–3.0X long as wide, stylus of slightly shorter. Thorax. Yellowish with scutum posteriorly, scutellum and mediotergite brownish; dark markings 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, but notopleural distinct, scutellars apparently absent. Legs. Whitish yellow, distal tarsomeres of all legs hardly darker. C1 ~1.3–1.4X longer than distance between base of C1 and C2; C1, C2 and C3 with all setulae minute. F1 ~1.0–1.1X long as C1; 4–5X long as wide, slightly constricted on inner face at 0.25 from base. F1 ventrally with two rows of ~5–6 yellow spines, inconspicuous except 1–2 near base stronger; between which are two rows of ~23 (anteroventral series) and ~18 (posteroventral series) minute black denticles. T1 ~0.7X 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 blackish microtrichia on distal 0.9; proximal 0.1 contrastingly yellowish white. Veins blackish on distal 0.9 except about base of R 1 and R 4; pale on proximal 0.1. R 2+3 linear, joining C ~ 0.7X distance between ends of R 1 and R 4. Length of C between ends of R 2+3 and R 4 ~1.7X long as R 4. R 4 hardly S-shaped, angle with R 5 at extreme base ~ 75–80°. R 5 long, ~3.0X 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, distinctly convergent distally. Cell bm+dm ending just beyond end of R 1. Halter yellowish white. Abdomen. Yellow but tergites 2–7 blackish. Setae mostly small and inconspicuous. Terminalia blackish. Cercus ( Figs 10–11 ) elongate, extending beyond tip of epandrium, apically expanded and crenulate with numerous conspicuous bristles on crenulations apically. Epandrium ( Fig.10 ) bluntly pointed apically, some distinct bristles distally. Two elongate processes emerging beyond tip of epandrium; upper process (upper lobe of surstylus?) large, L-shaped; lower process (lower lobe of surstylus?) with small black leaf-like appendage apically. Hypandrium strongly arched, lacking distinct setae. Phallus not examined. Female: similar to male but abdomen with sternite 7 black, terminalia elongate, somewhat ovipositor-like.

Type material. HOLOTYPE ♂: THAILAND, Satun Province, Wang Sai Thong waterfall, 92 m, 7.09092°N, 99.909274°E, 13.v.2019, netted A. R. Plant ( QSBG) . PARATYPES: 1♀, same data as holotype ( QSBG) ; 2♂, 1♀, Nakhon Si Thammarat Province, Nan Sawan waterfall, 331 m, 7.89195°N, 99.78899°E, 11.v.2019, netted A. R . Plant ( QSBG).

Etymology. The specific epithet honours Abdullah Samoh, fellow student of Empidoidea.

Remarks. The colour of the thorax of this species varies greatly from predominantly yellow with dark markings, to predominantly brownish and the species is probably best recognised by its distinctive male terminalia. The upper elongate process (here interpreted as the upper lobe of surstylus following Plant 2015) is distinctly L-shaped recalling particularly H. furcata Grootaert, Yang & Yang and H. yunnanensis (both widespread in Thailand) and H. digitata Grootaert, Yang & Saigusa (a species known from China, Yunnan) although many Asian species have apically inflated structures that despite being variously shaped, are probably analogous, and may be characteristic of a species-group within Hemerodromia ( Plant 2015) . Leaf-like appendages on the tip of the lower lobe of the surstylus are found in several regional species including H. anisoserrata Plant, H. betalutea Plant, H. fusca Yang &Yang, H. ocellata Plant and H. yunnanensis. The general pattern of colouration of the thorax and wing and crenulated dorsal process on the cercus of H. samoha sp. nov. recall H. namtokhinpoon Plant, a stenotopic tufa species only known from Loei province. The combination of cercus shape and form of the surstylus should enable identification of this species. Hemerodromia samoha sp. nov. is known from two tufa waterfall localities in the south of Thailand ( Fig. 16 ).

Figures

FIGURES 10–11. Male terminalia of Hemerodromia samoha sp. nov. 10, lateral view of terminalia; 11, dorsal view of cerci. Abbreviations: cer=cerci, epa=epandrium, hyp=hypandrium, lsur =lower lobe of surstylus, usur=upper lobe of 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.