Two new species of Anisotacrus Schmiedeknecht (Hymenoptera, Ichneumonidae, Ctenopelmatinae) with a key to Eastern Palaearctic species

Two species of genus Anisotacrus Schmiedeknecht, 1913, A. externus Sheng & Sun, sp. nov. and A. senticosus Sheng & Sun, sp. nov., collected from the Natural Reserve, Huairou, Beijing, are described and illustrated. A key to the Eastern Palaearctic species of Anisotacrus is provided.

Coloration (Fig. 1). Black, except for following: Face, clypeus except a small dark brown spot at the center of clypeal sulcus, mandible except teeth, malar space, maxillary palpi, labial palpi, ventral profiles of scape and pedicel, upper-posterior corner of pronotum, anterolateral portion of mesoscutum, tegula, subtegular ridge, fore and middle coxae, trochanters, hind trochantellus yellowish white. Dorsal profiles of scape and pedicel, basal portion of flagellum darkish brown; remainder of flagellum yellowish brown. Fore and mid femora, tibiae and tarsi, basal portion of hind tibia yellow brown. Hind tarsus brownish black. Posterior portion of second tergite, third and fourth tergites entirely brownish red. Metasomal sternites 2 and 3 whitish yellow, with small lateral longitudinal brown spots; sternites 4-6 almost entirely reddish brown. Ovipositor sheath irregularly blackish brown. Pterostigma and veins brownish black.
Etymology. The specific name is derived from the fore wing vein 2m-cu connecting to cubitus distal of lower-posterior corner of areolet.
Distribution. China. Differential diagnosis. The new species is similar to A. albinotatus Kasparyan, 2007, but can be distinguished from the latter by the following combination of characters: malar space about 0.6 × as long as basal width of mandible; areolet triangular, 2m-cu connecting to cubitus slightly distal of areolet (Fig. 8); hind coxa and posterior tergites of metasoma black. Anisotacrus albinotatus: malar space about 0.9 × as long as basal width of mandible; areolet receiving vein 2m-cu basal of lower posterior corner; hind coxa, second and subsequent tergites reddish brown.
Head. Inner margins of eyes (Fig. 14) slightly concave near antennal sockets. Face (Fig. 14) 1.2 × as wide as long, almost flat, shagreened, with dense fine indistinct punctures and yellowish white setae; upper margin with median narrow smooth longitudinal stripe and a small median tubercle. Clypeus approximately 3.3 × as wide as long, shagreened, lateral portion with sparse fine punctures, apical median smooth, shiny; apical margin slightly arcuate. Mandible with sparse punctures and dense long yellowish white setae; lower tooth distinctly wider and slightly longer than upper tooth. Malar space about 0.4 × as long as basal width of mandible. Gena (Figs 15, 16), vertex (Fig. 16) and frons shagreened, with dense yellowish brown setae. Gena strongly convergent backward. Postocellar line approximately 0.6 × as long as ocular-ocellar line. Antenna with 38 flagellomeres; ratio of length from first to fifth flagellomeres: 2.4:1.3:1.1:1.0:1.0. Occipital carina complete, genal carina joining hypostomal carina above base of mandible.
Metasoma. First tergite (Fig. 20) approximately 2.7 × as long as posterior width, straight, shagreened, apical half with sparse fine indistinct punctures; latero-median and dorso-lateral carinae absent; ventro-lateral carinae complete; spiracle small, circular, distinctly convex, located at 0.5 of first tergite. Second and third tergites (Fig. 21) shagreened. Second tergite approximately as long as apical width, anteromedian portion with weak indistinct transverse wrinkles; thyridium transverse, distance to basal margin of second tergite about as its length. Third tergite (Fig. 21) parallel laterally, 0.85 × as long as wide. Ovipositor sheath (Fig. 22) 5.5 × as long as maximum width, 0.2 × as long as hind tibia, upper and lower margins almost parallel.   (Fig. 13). Black, except for following: Lateral side of face widely and irregularly, labrum, mandible except teeth and dorso-posterior corners of pronotum yellowish white. Maxillary and labial palpi dark brown. Fore and middle tibiae and tarsomeres 1-4 brownish yellow. Basal half of hind tibia except basal end and tibial spurs reddish brown. Posterior portion of tergite 2, tergite 3 entirely and 4 except posterior margin brownish red. Pterostigma brownish black. Veins blackish brown.
Distribution. China. Differential diagnosis. The new species is similar to A. xanthostigma (Gravenhorst, 1829), but can be distinguished from the latter by the following combination of characters: areolet distinctly quadrilateral; first tergite evenly convex, without longitudinal groove; second tergite as long as apical width; third tergite distinctly shorter than its width; mesoscutum, tegulae, all coxae and trochanters black. Anisotacrus xanthostigma: areolet triangular; first tergite with longitudinal groove; second tergite longer than apical width; third tergite as long as apical width; anterolateral portion of mesoscutum with yellow spots; tegulae yellow; fore coxae and parts of trochanters yellow.

Discussion
The male of Anisotacrus xanthostigma displays some distinct variation (Kasparyan and Khalaim 2007), including a wide range of coloration. The original description of A. iyoensis (Uchida, 1953) was based on two male specimens, and is very similar to A. xanthostigma (Gravenhorst, 1829). Both species may be conspecific (Kasparyan and Khalaim 2007). For a decision, the type of A. iyoensis and more East Palaearctic material have to be studied in the future.