Description:
Female: The body is dorsoventrally flattened. The width of the thorax is generally 4-5 times greater than its height. The head is directed forward.
The head’s width equals its height (from the vertex to the mandibles). The vertex is narrow. The posterior ocelli are distant from the compound eyes; the distance between them is twice the distance between the posterior and anterior ocelli. The area of the three ocelli has longitudinal grooves forming a triangle that covers all three ocelli. The frons is not concave. From the anterior ocellus to near the antennal sockets is a longitudinal groove that bifurcates near the antennal sockets, each branch bordering the socket and forming an inverted “Y” shape. The areas above the frons are smooth and shiny. The compound eyes are oval, with a length approximately 2.3 times greater than the width. The compound eyes are bare, without hairs. The length of the compound eyes exceeds the length of the cheeks. The cheeks below the compound eyes are slightly swollen and smooth. The antennae have 12 segments and are clavate (club-shaped). The scape is flattened and triangular, with the basal angle extended and pointed like a spine, its length exceeding its width by 1.3 times, and about 3 times greater than the length of the second antennal segment. The second antennal segment has a length twice its width and is longer than the third antennal segment (6:5). The fourth antennal segment is shorter than the third and nearly equal in length to its width. The antennal club has 6 segments; the total length of the club segments is 4 times greater than their greatest width, and longer than the length of the scape, but its width is less than that of the scape (8:15).
The thorax is about 1.5 times longer than its width. The pronotum is horseshoe-shaped, with rounded, irregular punctate impressions. The mesoscutum has two longitudinal grooves; between these grooves, there is a wrinkled reticulate pattern, and the outer sides of the grooves are smooth. The scutellum and postscutellum are narrow and smooth. The propodeum is large relative to the scutellum and postscutellum; the length of the propodeum is equal to 2/3 the length of the mesoscutum. There is a longitudinal groove in the middle of the propodeum, and both sides are smooth. The forewing is 3.6-3.7 times longer than its width, the marginal vein is longer than the stigmal vein, and the postmarginal vein is absent.
The abdomen is approximately 2.6-2.7 times longer than its width. The first tergite is shorter than the second; tergites 2-4 are nearly equal in length; and tergite 5 is longer than tergites 4 and 6. There are two longitudinal ridges on each side of the tergites, from the base of the first tergite to the anterior part of the fifth tergite. The sculpture on the tergites is similar to that on the mesoscutum. The sides of the tergites, and tergites 5 and 6, have short, sparse hairs.
The body is black; the compound eyes are silvery-white. The mandibles and antennae from the radicle to the seventh segment are brown, while the remaining segments are black. The wing veins are brown. The legs are yellow.
Male: Similar to the female in shape, color, and body sculpture. It differs from the female in that the antennae are 12-segmented and filiform (thread-like); the scape is flattened, but the side angle is not extended and pointed like a spine; the second antennal segment is small, with equal length and width (5:5). The third antennal segment is about 2.3 times longer than its width and is 2.8 times longer than the second antennal segment. The fourth and fifth segments are equal in length and width and shorter than the length of the third segment. Segments 6-11 are equal in length. The twelfth segment is longer than the eleventh and longer than the third segment (18:14). The abdomen has 7 segments.
Size: Body length 4.3 – 4.7mm.
Distribution: Vietnam: Son La, Thai Nguyen, Gia Lai, Dong Nai.
Examined Material:
- 2 Males, Son La, 2/5/1986 (A. Sarkov, V. Triapitxun).
- 4 Males, Thai Nguyen (Phu Luong) 4/1986 (A. Sarkov).
- 5 Males, Gia Lai (An Khe, Buon Loi) 7/1982 (Le Xuan Hue).
- 2 Females, Dong Nai (Ma Da) 11/1989 (Le Xuan Hue).
(Specimens are stored at the Institute of Ecology and Biological Resources (Hanoi).)