Mesochorus ( Stictopisthus ) megacephalus, Riedel, 2025

Mesochorus ( Stictopisthus) megacephalus nov.sp. (figs 9, 31, 46, 63, 74)

H o l o t y p e: ( ♀) “V.-Ussur. Station 40 km south of Chuguevka, Kasparyan 23 VII 1970 ” ( St.

Petersburg). D e s c r i p t i o n: ♀. Body length 3.9 mm. Flagellum with 27 segments; 1st flagellar segment 6.9× as long as wide and 0.59× as long as eye; 2 nd segment 4.7× and preapical segment 2.0× as long as wide. Temple slightly widened behind eye and slightly narrowed apically, dorsally as long as eye. OED 2.0× and OOD 1.1× ocellar diameter. Occipital carina complete. Vertex with sparse punctures, gena coarsely and densely punctate. Frons almost smooth, Face with coarse dense punctures, its width 1.1× combined length of face and clypeus and 1.1× eye length, with parallel sides. Clypeus impressed, almost smooth. Mandible not swollen, with two equal teeth. MI 0.5.

Mesosoma strongly depressed, 2.1× as long as high. Side of pronotum with fine sparse punctures dorsally, almost smooth ventrally. Mesoscutum with fine rather dense setiferous punctures. Scuto-scutellar groove slit-shaped, smooth. Mesopleuron densely punctate dorso-frontally, with very sparse punctures ventrally. Metapleuron with dense and coarser punctures. Propodeum with complete carination, but area basalis and area superomedia confluent. Costula reaching area superomedia at its middle. Area petiolaris about as long as wide. Hind femur 3.4× as long as wide. Inner apical spur of hind tibia 0.58× as long as hind metatarsus. Hind claws without visible teeth. Areolet pointed frontally; vein 2m-cu reaching proximad its middle. Vein 1cu-a moderately postfurcal by 0.3× its length. Pterostigma 3.0× as long as wide; distal part of metacarpus long, c. 1.0× as long as width of pterostigma. Hind wing with 4 distal hamuli; nervellus vertical, not intercepted.

1 st tergite 2.5× as long as wide; postpetiole with rather coarse longitudinal rugae. 2 nd tergite 0.9× as long as wide. Thyridium transverse-oval. Ovipositor sheath pilose, 6.3× as long as wide and 0.9× as long as hind metatarsus, not distinctly narrowed and slightly bent upwards apically.

Color: black. Head reddish; face except red facial orbit brownish. Mandible except teeth and palps yellow. Stemmaticum and occiput brown. Flagellum blackish; three basal flagellomeres, scape and pedicel yellowish. Mesosoma black; hind edge and ventral spot on pronotum and tegula yellow. Tergites black; 2 nd tergite with reddish-yellow band in apical 0.3; 3 rd tergite reddish-yellow antero-medially, black laterally and apically. Legs yellow; hind coxa reddish; hind tibia cream-yellow, brown at apical 0.15 (1× tibial diameter); hind tarsomeres yellowish, with reddish tips. Pterostigma hyaline.

³ unknown.

R e m a r k s: This new species resembles Mesochorus macrocephalus STROBL but differs by its sparsely punctate mesopleuron, ± widened temple and normal mandible which is not distinctly swollen as in Mesochorus macrocephalus STROBL.

D i s t r i b u t i o n: Only known from Far East Russia.