Oedalea vietnamensis Shamshev, 2020

Shamshev, I. V., 2020, First record of the genus Oedalea Meigen (Diptera: Hybotidae) from Vietnam, with description of a new species and a key to species of the Oriental Region, Russian Entomological Journal 29 (2), pp. 218-221 : 219-220

Oedalea vietnamensis Shamshev , sp.n.

Figs 1–4 .

TYPE MATERIAL. Holotype, ♂, labelled: VNM [= VIETNAM]: Lai Châu Prov., Hoàng Liên N.P., 22.34997°N, 103.76818°E, 1947 m, 19.iv.2012, D. Gavryushin ( ZMMU) . Paratype, 1 ♂, same data as holotype ( ZIN, dissected) .

DIAGNOSIS. Antennae with postpedicel yellowish brown, postpedicel about 10X longer than wide, stylus slen- der, with seta-like apical segment, palpus black; thorax with yellowish stronger setae, six scutellars; legs extensively yellowish; wing uniformly faintly infuscate, M 2 complete, pterostigma distinct, large; halter with darkened knob.

DESCRIPTION. Male ( Fig. 1 ). Head black. Eyes holoptic, upper ommatidia enlarged. Frons represented by very small subtriangular space above antennae, subshiny, faintly pruinose. Face short, broad, shiny (including clypeus). Ocellar triangle subshiny, with 2 short dark setae. Occiput densely greyish pruinose; with rather sparse, black, moderately long setae on upper part (including postoculars) and some yellowish fine setae on lower part behind mouth-opening. Antenna with scape, postpedicel and stylus brownish, postpedicel yellowish brown to reddish brown; scape and pedicel with dark setulae (more numerous and distinct on pedicel); postpedicel very long, about 10x longer than wide near base; stylus very short, slender, with seta-like apical segment. Palpus short, black, with scattered black setulae. Proboscis brownish, labrum nearly half of eye height.

Thorax almost entirely black, only prothoracic sclerites (except antepronotum) and postalar tubercle reddish brown; extensively shiny, prothoracic sclerites, notopleuron narrowly along lower margin posteriorly, almost entirely laterotergite (except narrow space on lower part) and mediotergite (except two small lateral spots) tomentose; pale to yellowish (stronger setae) setose. Proepisternum bare on lower portion, with 2–3 short fine setae on upper portion opposite anterior spiracle. Antepronotum with several setulae on each side dorsally. Postpronotal lobe with several setulae. Mesonotum with 1 long strong notopleural (with 2 additional short fine and some minute setae), 1 moderately long and 1 minute postalars, 6 scutellars (two inner pairs very long); mesoscutum almost entirely covered with uniform setulae, multiserial acrostichals separated narrowly from dorsocentrals only before suture, 1 pair of very long dorsocentral prescutellars. Anterior and posterior spiracles brown.

Legs extensively yellowish (including coxae), only hind tibia (except extreme base and apex), apicis of basitarsi and entire tarsomeres 2–5 brownish; subshiny, mostly with inconspicuous setation (except noted). Hind leg raptorial, with incrassate femur and geniculate, somewhat thickened and arcuate tibia. Coxae and trochanters with yellowish to pale setae. Femora with pale setae (except noted); fore and mid femora equally slender; hind femur with long fine setae posterodorsally and posteriorly on about basal 2/3, numerous black spinelike setae beyond middle toward apex ventrally. Fore tibia almost uniformly somewhat thickened (except extreme base).

Wing membrane faintly brownish. Basal costal seta present, long, yellowish. Pterostigma distinct, brownish, subrectangular, covering about third distance between apicis of R 1 and R 2+3, lower margin almost reaching to R 2+3. Veins brownish, mostly well sclerotised; R 2+3 slightly sinuate apposite pterostigma; all branches of M reaching wing margin; CuA+CuP (anal vein) evanescent toward wing margin, almost complete, reaching wing margin as fold. Cell dm very large and long, almost truncate, with very slightly produced apex. Anal lobe well-developed; axillary incision obtuse, closer to 90°. Squama pale yellow, pale fringed. Halter with darkened knob and yellow stem.

Abdomen with blackish brown tergites and brownish sternites, entirely shiny; covered with rather sparse yellowish to pale setae longer on tergites laterally.

Terminalia ( Figs 2–4 ) small, elongate oval, brownish, subshiny. Cerci ( Fig. 3 ) digitiform, of subequal length and width, slightly narrowed apically, covered with scattered, short, simple setae. Right epandrial lamella ( Fig. 2 ) subrectangular (lateral view), with several very long setae along ventral margin; right surstylus broad, rather subglobular, mostly with simple short setae. Left epandrial lamella ( Fig. 4 ) subrectangular, with several very long setae along ventral margin; left surstylus broad, somewhat concave apically, covered with mostly short simple setae, some longer setae along ventral margin.

MEASUREMENTS. Body 3.7 mm, wing 3.5 mm.

Female. Unknown.

DIFFERENTIAL DIAGNOSIS. Main differences between the new species and other Oriental species of Oedalea are indicated in the key given below. Among the Palaearctic species O. vietnamensis sp.n. resembles O. freyi Chvála, 1983 , known only from the north of Fennoscandia. Howev- er, O. freyi can be readily distinguished from the new species by shorter, evenly conical postpedicel [ Chvála, 1983: 167, Fig. 381], usually 8 scutellar setae (only one inner pair stronger) and uniformly yellowish halteres.

ETYMOLOGY. The epithet refers to the country of the origin of the new species.

DISTRIBUTION. Oriental: Vietnam.

Figures

Fig. 1. Oedalea vietnamensis sp.n., male, habitus, holotype. Рис. 1. Oedalea vietnamensis sp.n., самец, габитус, голотип.

Figs 2–4. Oedalea vietnamensis sp.n., male: 2 — right epandrial lamella; 3 — cerci and epandrium; 4 — left epandrial lamella; 2, 4 — lateral view; 3 — dorsal view. Abbreviations: cerc — cercus; epand — epandrium; sur — surstylus. Рис. 2–4. Oedalea vietnamensis sp.n., самец: 2 — праваЯ лопасть ЭпандриЯ; 3 — церки и Эпандрий; 4 — леваЯ лопасть ЭпандриЯ; 2, 4 — сбоку; 3 — сбоку. СокраЩениЯ: cerc — церк; epand — Эпандрий; sur — сурстиль.