Hemerodromia oretenebraea, 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 : 553-554

Hemerodromia oretenebraea sp. nov.

( Figs 5–7 , 14 )

Diagnosis. A blackish species with head and thorax rather quadrate. The anterior of the wing is covered with dark microtrichia, usually contrasting strongly with the posterior part. The front femur is deep black, contrasting strikingly with otherwise pale yellowish legs.

Description. Male: body length 2.8 mm; wing length 1.8 mm. Head. Rather short, only slightly longer than deep, rather quadrate (especially in dorsal view); upper occiput vertical in lateral view, upper part slightly but distinctly bulging where meeting vertex. Black, dusted greyish; antenna blackish; mouthparts pale yellow, proboscis with darker tip. One pair reclinate ocellar setulae; 4–5 pairs small indistinct vertical setulae, about as strong as ocellars; pair of minute frontals behind base of antenna. Antenna with postpedicel <1.5X long as wide (viewed laterally); stylus about as long as postpedicel; scape with small fine dorsal setae. Thorax. Distinctly quadrate anteriorly; anterior margin of scutum vertical in lateral view making distinct but smooth right angle with disc (not gradually curving). Ground colour deep black, dusted greyish. All setae black, minute apart from one small notopleural. Scutellum with one subapical pair of very small convergent setae. Legs. Pale yellowish with apical tarsomeres somewhat darker, F1 and front trochanter contrastingly black. C1 about as long as distance between C1 and C2, a more or less linear series of minute setulae along length of limb dorsally. F1 hardly longer than C1, distinctly inflated, ~ 4–5X long as wide, not constricted on proximal 0.3. F1with two closely spaced rows of ~ 15–21 minute black denticles, either side of which is linear series of ~ 5–6 less numerous, rather hair-like yellowish or brownish spines, noticeable stronger and more bristle-like about 0.2 from base.T1 ~ 0.7X long as F1, sublinear, ventral face only slightly concave; with one row of ~12 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 distinctly darkened with blackish microtrichia, especially anteriorly of M in distal part of wing beyond radial fork; cell bm+dm, base and posterior part of wing paler. Veins greyish black, R 2+3, R 4+5, R 4 and R 5 distinctly darker and somewhat thickened. Marginal setulae greyish black. 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 ~ 1.0–1.1X long as R 4. R 4 slightly S-shaped, angle with R 5 at extreme base ~ 65–70°. R 5 ~ 1.7–2.0X long as R 4, almost linear, almost parallel with M 1 but divergent apically. Cell bm+dm rather long, ending distinctly beyond end of R 1. Halter greyish white. Abdomen. Blackish, all setulae inconspicuous, very short, dark, a few longer setulae on sternites 7 and 8. Terminalia. Black with dark setae. Moderately small and compact. Cercus ( Figs 5–6 ) elongate, extending beyond tip of epandrium, narrow in lateral view, inner margin distinctly evenly concave in dorsal view. Epandrium ( Fig. 5 ) rather ovate with some fine setae and patch of microscopic pile distally. Surstylus apparently more or less fused with tip of epandrium, bearing two distinct spines ( Fig. 7 ). Hypandrium ( Fig. 5 ) short, compact, distinctly arched. Apex of phallus bifid in posterior view. Female: similar to male but abdomen with shorter setulae and terminalia elongate, ovipositor-like.

Type material. HOLOTYPE ♂: THAILAND, Loei Province, Hin Pha Ngam, Pang Din waterfall, tufa stream, 628 m, 17.06639°N, 101.74813°E, 5.iii.2019, netted A. R. Plant ( QSBG) . PARATYPES: 4♀ same data as holo- type ( QSBG) ; 1♀, Phang Nga Province, Sa Nang Namora waterfall, tufa stream, 59 m, 8.51063°N, 98.54140°E, 16.i.2019, netted A. R . Plant ( QSBG) ; 7♂, Lampang Province, Wang Kaew waterfall, 568 m, 19.3164°N, 99.6628°E, 14.i.2020, netted A. R . Plant ( QSBG) ; 1♂, Phrae Province, Huai Rong tufa waterfall, 450 m, 18.4424°N, 100.4495°E, 18.i.2020, netted A. R . Plant ( QSBG) .

Additional material. 2♂, 1♀, Chiangrai Province, Doi Luang National Park, Pu Kaeng waterfall, 540 m, 19.4422°N, 99.6949°E, 15.i.2020, netted A. R . Plant ( QSBG) ; 2♂, 4♀, Lampang Province, Mae Kae waterfall, 537 m, 18.7457°N, 99.8164°E, 16.i.2020, netted A. R . Plant ( QSBG) .

Etymology. The specific epithet is derived from the Latin ore, meaning ‘edge’ and tenebrae meaning ‘darkness’ in reference to the darker membrane on the anterior part of the wing.

Remarks. The quadrate, head and thorax and relatively simple and small male terminalia with fused surstylus bearing two spines suggest that this species is related to H. conspecta Plant, also from Thailand. However, it may readily be distinguished by the bulging occiput, vein C being all dark (basally yellow in H. conspecta), wing distinctly darkened anteriorly and having F1 black (yellow in H. conspecta) contrasting strongly with the rest of the legs as well as shape of the cercus and surstylus of the male terminalia. In some examples the wing is more gener- ally darkened although still darker anteriorly. Although darkened front femora are found in several other species of Hemerodromia , the front coxa is seldom clear yellow as in the new species where the contrast between the front femur and coxa is striking, and is a rare example of leg colour being diagnostically useful in the genus. Hemerodromia oretenebraea sp. nov. has a disjunct distribution occurring at several sites in the north and one in the south of the country ( Fig. 14 ).

Figures

FIGURES 5–7. Male terminalia of Hemerodromia oretenebraea sp. nov. 5, lateral view of terminalia; 6, dorsal view of cerci; 7, left surstylus in oblique sinistro-ventral view. 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.