Platypalpus phomyaaw, 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 : 4039-4041

Platypalpus phomyaaw sp. nov. (male)

( Figures 7–10 )

Etymology

The name ‘‘phomyaaw’’ refers to the long bristles on the abdominal sternites 5 and 6 (in Thai ‘‘yaaw’’ means ‘‘long’’ and ‘‘phom’’ means ‘‘hairs or bristles’’).

Diagnosis

Mostly yellow (including legs) species; one pair of verticals; occiput narrowly densely greyish pollinose behind eyes, otherwise subshining; mesonotum wholly yellow, thoracic pleura partly brown; abdominal sternite 5 with two, sternite 6 with four very long bristles posteriorly.

Material examined

Holotype: male, 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.

Male

Body length 2.9 mm; wing length 2.9 mm.

Head. Black in ground-colour. Occiput narrowly densely greyish pollinose behind eyes, otherwise subshining; bearing scattered pale bristly hairs, with two short verticals. Ocellar tubercle with two short bristles. Frons finely pollinose, mostly very narrow, narrower than anterior ocellus, somewhat widened above. Face concolorous with frons. Basal antennal segments brown; postpedicel and arista missing. Palpus small, wholly yellow, mostly with scattered, short, yellow bristly hairs, bearing one longer, yellowish, subapical bristle.

Thorax. Largely yellow; prothoracic notum brownish dorsally, prosternum yellowish brown, sutures of prothoracic sclerites brown in varying extent; sternopleuron almost wholly (except for upper posterior corner) dark brown, hypopleuron largely brown (yellow in upper third), metapleuron brown; postnotum with metanotum brown; metapleuron brown. Mesonotum and sternopleuron shining, otherwise thorax finely pollinose, subshining. Anterior and posterior spiracles brown. Humerus with one minute bristle. Mesonotum with brownish yellow, short, inconspicuous setation including two notopleural (anterior one shorter and thinner), one postalar and two scutellar (missing) bristles; some scattered setulae present behind humerus, on notopleural depression, supraalar space and postalar callus. Acrostichals lacking. Dorsocentrals arranged in one row, few in number, mostly of subequal length (except for one longer prescutellar pair).

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 (nearly half as long as femur is deep), 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 black, ventral spinules and a row of moderately long (at most as long as femur is deep), brown, posteroventral bristles. Mid tibia with black ventral spinules throughout and short 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; basicostal bristle missing. Vein M1+2 somewhat bowed in apical part but parallel to vein 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 and with long, pale fringes. Halter pale yellow.

Abdomen. Yellowish brown, subshining, mostly with scattered distinct setulae becoming longer and more numerous toward terminalia; sternite 5 with two, sternite 6 with four very long yellowish brown bristles posteriorly.

Terminalia ( Figure 7 ). Moderately large, elongate, rotated 45 °, epandrium largely brownish yellow to yellow, cerci brownish. Left epandrial lamella ( Figure 9 ) elongate and covered with numerous bristles in upper part. Left surstylus subtriangular, rather large, with several long bristles. Right epandrial lamella ( Figure 10 ) subtriangular, with short more or less rounded process, bearing scattered moderately long bristles. Right surstylus small, subtriangular. Cerci ( Figure 8 ) digitiform, very long (left cercus longer), pubescent, clothed with short scattered bristles. Hypoproct ( Figure 8 ) greatly modified, extending far beyond apices of cerci, overlapping apical part of right epandrial lamella, broadened in apical part.

Female

Unknown.

Distribution

Thailand.

Remarks

In having a wholly yellow mesonotum and, especially, a peculiar structure of the male terminalia, P. phomyaaw sp. nov. is most closely related to P. gaemluang sp. nov. It can be readily distinguished from the latter by partly brownish thoracic pleura and by two and four very long bristles on abdominal sternites 5 and 6, respectively. Two other species with wholly yellow mesonotum are P. candidiseta and P. sanguinolentus ( Bezzi 1912; de Meijere 1914). The former differs from P. phomyaaw sp. nov. by wholly black thoracic pleura. The latter can be readily distinguished from the new species by the wholly black scutellum and largely black thoracic pleura.

Figures

Figures 7–10. Platypalpus phomyaaw sp. nov., male. (7) Hypopygium (lateral view). (8) Epandrium with cerci and hypoproct. (9) Left epandrial lamella (lateral view). (10) Right epandrial lamella (lateral view). Scale bar: 0.5 mm (7); 0.1 mm (8–10).