Platypalpus isaanensis, Grootaert & Shamshev, 2006

Grootaert, Patrick & Shamshev, Igor, 2006, The genus Platypalpus Macquart (Diptera: Hybotidae) from Northeast Thailand with comments on the species groups in the Oriental region, Journal of Natural History 39 (47), pp. 4031-4065 : 4050-4051

Platypalpus isaanensis sp. nov. (female)

Etymology

The name ‘‘isaanensis’’ refers to Northeast Thailand which is called ‘‘pak isaan’’ or simply ‘‘isaan’’.

Diagnosis

Mostly yellow, including legs, species; one pair of verticals; antenna yellowish brown, arista white, postpedicel 4.0 times longer than wide, arista 2.5 times longer than postpedicel; mesonotum with two brownish spots, sternopleuron and hypopleuron wholly brown to yellowish brown.

Material examined

Holotype: female, Thailand, Loei province, Na Haeo, Chang Tok waterfall, 17 May 2003, sweep netting on vegetation bordering the river Mae Heuang (sample no. 23035), leg. P. Grootaert. Paratype: one female, Thailand, Loei province, Na Haeo, Khring Tok waterfall, 19 May 2003, sweep netting on vegetation bordering the river Mae Heuang (sample no. 23043), leg. P. Grootaert.

Male

Unknown.

Female

Body length 2.8–2.9 mm; wing length 2.3–2.4 mm.

Head. Black in ground-colour. Occiput wholly subshining, with two short verticals. Ocellar tubercle with two short and two minute bristles. Frons pollinose. Antenna yellowish brown, arista white, thick pubescent. Postpedicel narrow, elongate conical, nearly 4.0 times longer than wide. Arista nearly 2.5 times longer than postpedicel. Palpus wholly yellow, small, mostly with scattered, short, yellow bristly hairs, bearing one longer, brownish yellow subapical seta.

Thorax. Largely yellow; prothoracic notum brown; prosternum brownish yellow; suture between proepisternum and mesopleuron brown; mesonotum with two brown, distinct, subtriangular spots above wings; sternopleuron and hypopleuron wholly brown to yellowish brown; mesopleuron brownish yellow in upper part; metapleuron brown; postnotum with metanotum brown. Mesonotum and sternopleuron shining, otherwise thorax finely pollinose, subshining. Anterior and posterior spiracles brown. Humerus with one very short, fine bristle. Mesonotum with two brownish notopleural (anterior one shorter and thinner), one postalar (similar to posterior notopleural), and four scutellar (outer ones very short, thin; inner ones longest among mesonotal bristles, cruciate) bristles; some scattered setulae present behind humerus, on notopleural depression, supra-alar space and postalar callus. Acrostichals lacking. Dorsocentrals arranged in one regular row, few in number, short, mostly of equal length (except for two pairs of longer prescutellars).

Legs. Wholly yellow. Coxae and trochanters with ordinary yellow to brownish yellow setae. Fore femur slender, with a row of brownish yellow, thin, posteroventral bristles (one longest one in middle part of femur longer than femur is deep) and a row of yellowish, short, thin, anteroventral bristles. Fore tibia mostly slender, somewhat swollen near tibial gland; clothed with ordinary setulae. Fore tarsus slender, unmodified. Mid femur incrassate, nearly 2.0 times broader than fore femur; with rows of ventral black spinules and a row of moderately long (as long as femur is deep), brown, posteroventral bristles. Mid tibia with black, ventral spinules throughout and hardly prominent, flattened, apical spur. Hind leg long, slender; hind femur somewhat swollen in apical part anteriorly, bearing a row of short, brownish to brownish yellow, erect, antero- and a row of short, pale, posteroventral bristles.

Wing. Slightly infuscate, bearing one long, brownish, basicostal bristle. Vein M1+2 somewhat bowed in apical part but parallel to R4+5 near wing-apex. Crossveins m-cu and r-m contiguous. Cell br broader than cell bm. Vein CuA2 somewhat sinuate, recurrent. Vein A1 long. Squama brownish yellow, with long, brownish fringes. Halter pale yellow.

Abdomen. Tergites brownish yellow; sternites mostly yellow, preapical ones brownish to brownish yellow. Cerci pale yellow.

Distribution

Thailand.

Remarks

P. isaanensis sp. nov. is most similar to P. nuadkhao described here. However, P. isaanensis sp. nov. has shorter postpedicel and a different pattern of brownish space on the mesopleuron. Real size of the body of the new species is probably smaller since in both specimens last abdominal segments are entirely extruded.