Microchelonus nigellus Tobias, sp. n. (figure, 13-16)

Material. Holotype ♀ [without right fore wing and right hind tarsus], with 3 labels [date and locality of collection not indicated (? Central Europe)]—"Coll. Foerster," "Chelonus nigellus m.," "16 gl. [antennal segments], ♀"—handwritten and partly illegible. Deposited at MNHU.

Description. Female. Head slightly roundly narrowing behind eyes; its width 1.1 times that of mesonotum, 1.8 times its own length, 1.25 times its height. Temples slightly longer than transverse eye diameter (11 : 10). Width of ocellar triangle equal to the distance from it to eye. Distance between posterior ocelli 3 times ocellus diameter. Longitudinal eye diameter 1.6 times transverse one, twice gena height, 0.77 times face width. Face convex along the middle in the form of gently sloping carina; face height 0.59 times its width, 1.7 times clypeus height. Antennae thickened in the middle; 1 st flagellar segment 4 times, 4th and 5th 3 times, 6th twice, 8th 1.3 times as long as wide; three apical segments considerably narrower than preceding segments, 1.3-1.5 times as long as wide. mesosoma length 1.2 times its height. Propodeum without transverse carina; with rather small, slightly pointed lateral processes. Radial cell twice as large as 2nd radiomedial one, its anterior margin as long as pterostigma. 3rd radial abscissa weakly S-curved, 6 times as long as 2nd one, 1.7 times as long as 1 st radiomedial vein. 1 st radial abscissa slightly longer than 2nd (4 : 3). Nervulus at distance equal to its own length from basal vein. Hind femur 4 times as long as wide. Hind tibia as long as hind tarsus. Inner spur of hind tibia 0.4 times as long as 1st segment of hind tarsus; 5th segment of hind tarsus longer than 3rd but shorter than 2nd. Abdominal carapace oval, bent downward apically along 0.15 of its length, strongly widened in apical third, twice wider there than at base, 1.8 times as long as wide, 3 times as long as high. Ovipositor concealed.

Vertex behind ocelli and temples with numerous fine transverse rugae. Face and frons with concentric rugae rather coarse on frons and weaker and less noticeable on face. Mesonotum with fine reticulate sculpture. Scutellum rugose, dull. metasoma with moderately coarse longitudinal rugae weakly sinuate and slightly anastomosing in basal half and finer, more sinuate and anastomosing in posterior half.

Body black. Apex of fore femur and entire fore tibia yellowish brown. Middle and hind tibiae brown, with yellowish band in the middle. All tarsi brown. Wings faintly infuscate; pterostigma and veins brown.

Body length 3.5 mm.

Male unknown.

Differential diagnosis. M. nigellus can be related to M. ripaeus Tobias, 1986 in the apically widened metasoma, but in the former species this character is much more noticeable. In addition, it differs from M. ripaeus in the much longer flagellar segments. Among Mongolian species, M. nigellus is most closely related to M. insepultus Tobias, 1989; differing in the structure of metasoma, antennae thickened in the middle part and having considerably longer basal flagellar segments, and longer radial cell. In the structure of antennae and other characters, except for the shape of the metasoma, this species is similar to the Far Eastern M. errattts nom. n. (see below), differing in the flagellum more thickened medially and much longer basal flagellar segments.