Ismarus unisulcus Chen & Yan sp. nov.

Figs 3, 4

Material examined.

Holotype. China • 1♀; Yunnan Province, Gaoligongshan National Nature Reserve, Dulong River, GLG13; 27°50'55.81"N, 98°28'3.15"E, 2824 m; 2-15 Jul. 2020; Lang Yi leg.; Malaise trap; SCBG 3044337 . Paratype. China • 1♀; same locality as holotype, but 2-16 Jul. 2020; Lang Yi leg.; Malaise trap; SCBG 3049369 .

Diagnosis.

This species is most similar to I. halidayi Förster but can be distinguished by the following characters: A4 slightly longer than A3 (A4 shorter than A3 in I. halidayi); median furrow of T2 very short, distinctly less than half the length of T2 (median furrow of T2 long, reaching half the length of T2 in I. halidayi); radial cell of fore wing 0.75 × as long as marginal vein (radial cell as long as marginal vein in I. halidayi).

Description.

Female. Body length 2.50-2.64 mm.

Colour. Body black; A1-A9 brown to dark brown, remainder of antenna dark brown; fore and mid legs yellow-brown, with tarsi becoming darker distally, hind leg mostly dark brown with basal coxae somewhat dark and hind femur, trochanter and basal tibia yellow-brown; tegulae yellow-brown; wings hyaline, veins light brown to black-brown.

Head. Head 2.0 × as wide as long in dorsal view; vertex abruptly sloping behind ocelli in lateral view; POL as long as OOL; most of frons with scattered setae, except densely setose ventro-laterally; transverse facial carina slightly convex ventrally; A4 slightly longer than A3; A4 1.5 × length of A5; A6-A14 with each segment less than 1.5 × as long as wide; A15 approximately 2.0 × longer than wide.

Mesosoma. Dorsal pronotal area rugose-punctate and setose; lateral pronotal area rugose-punctate ventrally, smooth dorsally; mesoscutum smooth, shiny and convex, posterior margin with scattered long setae; mesoscutal suprahumeral sulcus present as a single anterior pit; mesoscutal humeral sulcus as long as tegula, deep and crenulate; mesoscutellum smooth and slightly convex, posterior rim rounded; anterior mesoscutellar pit large and deep, shorter than length of the mesoscutellar disc, sparsely punctate posteriorly, median keel weakly defined; mesopleuron smooth, with area below tegula rugulose; metapleuron rugose-punctate and covered with dense, long whitish setae.

Wings. Radial cell closed, moderately large, 5.6 × as long as wide and 0.94 × as long as marginal vein.

Legs. Fore and mid legs slender; hind tibia gradually swollen, its maximum width slightly wider than hind femur.

Metasoma. Petiole slightly shorter than wide (8:9), with strong costae dorsally; tergites smooth with scattered fine punctures; base of T2 with two short costae and a short median furrow, extending 0.37 × length of T2; sutures between tergites complete and deeply impressed.

Male. Unknown.

Etymology.

The name refers to the single furrow present on the base of T2.

Distribution.

China (Yunnan).