Thressa foliacea, Liu, Xiao-Yan, Yang, Ding & Nartshuk, Emilia P., 2011

Liu, Xiao-Yan, Yang, Ding & Nartshuk, Emilia P., 2011, Species of the genus Thressa Walker, 1860 from China (Diptera, Chloropidae), ZooKeys 129, pp. 29-48 : 35-36

Thressa foliacea sp. n. Figs 2028

Diagnosis.

Antenna black; postpedicel 2.5 times as long as wide. Thoracic pleuron bright black except katepisternum, anepimeron and katepimeron with some pale gray microtomentum; paratergite and dorsal portion of anepisternum with a trapezoidal, bright yellow spot. Surstylus short, leaf-shaped.

Description.

Male.Body length2.3 mm, wing length1.9 mm.

Head (Figs 20, 21) black without microtomentum, about 0.9 times as long as high, wider than thorax; face sometimes concave in lateral view, bright brown with two yellow spots below antenna; epistoma yellow; frons black, 1.1 times as long as wide, projecting only slightly in front of eye, almost entirely occupied by broad ocellar triangle; gena narrow; vibrissal angle obtuse; parafacial black, linear; postgena black; clypeus light black. Ocellar triangle very large and broad, smooth, black, shiny metallic blue, reaching to anterior margin of frons with broad apex; ocellar tubercle black. Occiput black. Cephalic setae and setulae black, weakly developed; if extremely short, in 1 row on the surface of the triangle; orb very minute, upright; oc subequal to orb; pvt small hair-like, upright, convergent; vte shorter than pvt and vti indistinct. Antenna black with thick grayish microtomentum; postpedicel 2.5 times as long as wide, parallel-sided; arista missing in holotype. Proboscis and palpus blackish brown with brownish setulae.

Thorax (Figs 22, 23) shiny black without microtomentum, with granulated microsculpture, evenly covered with short setulae. Scutum strongly convex, almost as long as wide. Thoracic pleuron bright black except for katepisternum, anepimeron and katepimeron with some pale gray microtomentum; paratergite and dorsal portion of anepisternum with a trapezoidal, bright yellow spot. Scutellum about 0.5 times as long as wide; ap sc short, distinctly shorter than scutellum. Setae and setulae on thorax black. Legs black except for distal part of femora, entire tibiae and tarsi yellow. Setulae on legs yellow, but apical portion of tarsi with some brown setulae. Tibial organ distinct, oblong. Wing (Fig. 24) about 2.9 times as long as wide, hyaline with a brown spot near wing apex, costal cell somewhat tinged with brown; veins brown. Relative lengths of 2nd: 3rd: 4th costal sections = 5: 2.5: 1; discal cell narrow and long; crossveins r-m and m-m not approximate, r-m at basal 1/3 of discal cell. Halter pale yellow on knob, brown on stem.

Abdomen shiny black; venter yellow. Setulae on abdomen black. Male genitalia (Figs 25-28): Epandrium short tubular, weakly sclerotized, black with long black setulae; surstylus short, leaf-shaped with short spinous setulae. Cercus with a concavity on ventral margin. Gonites arranged in a row; postgonite slightly incurved distally with blunt apex, basal 1/4 obviously narrowed, with some sensory setulae; pregonite shorter, about 0.5 times as long as postgonite, basally broad, distally narrowed; basiphallus longer than wide, cylindrical; distiphallus cylindrical, longer than basiphallus, beyond lower margin of hypandrium, largely membranous but weakly sclerotized on apical end; phallapodeme long, extended near base of basiphallus, with basal stalk short and broad in lateral view. Hypandrium broad.

Female. Unknown.

Type material.

Holotype ♂, Hainan: Baisha (19°11'N, 109°25'E, 430m), 19. X. 2007, Xingyue Liu. Male type specimen dry mounted on label laterally on right thorax; arista is missing.

Distribution.

China: Hainan.

Remarks.

The new species is somewhat similar to Thressa punctifera (de Meijere) in the wing with a brown spot near the wing apex and the abdomen shiny black. But it can be separated from the latter by the paratergite and dorsal portion of the anepisternum with one trapezoidal, bright yellow spot; the legs black except for the distal part of femora, entire tibiae and tarsi yellow; the surstylus short, leaf-shaped. In Thressa punctifera , the katepisternum has one narrow yellow spot; the legs are yellow except for the fore femora brownish; the surstylus is broad basally and narrow distally ( de Meijere 1910; Nartshuk 1993).

Etymology.

The specific name is from the Latin foliaceus ( “leaf-shaped”), refers to the leaf-shaped surstylus.