A new species and new records of the genus Alexeter Förster (Hymenoptera, Ichneumonidae, Ctenopelmatinae) from Beijing with a key to Chinese species

Abstract A new species, Alexeterbeijingensis Sheng, sp. nov., and two new records for China, A.angularis (Uchida, 1952) and A.shakojiensis Uchida, 1930, collected in Mentougou, Beijing, belonging to the tribe Mesoleiini of the subfamily Ctenopelmatinae (Hymenoptera, Ichneumonidae), are reported. A key to the six species of Alexeter known from China is given.

In this paper we deal with all Alexeter species from China, including the description of a new species and a key to all known species from the country.

Materials and methods
Specimens were collected by interception traps (IT) (Li et al. 2012) in the forest of Mentougou, Beijing, P.R. China. The forest of Mentougou is composed of mixed deciduous angiosperms and evergreen conifers (Zong et al. 2013). Images were taken using a Leica M205A stereomicroscope with LAS Montage MultiFocus. Morphological terminology is mostly based on Gauld (1991 Gauld et al. 1997, Townes 1970. Clypeus separated from face, apical margin blunt, weakly concave or centrally truncate. Occipital carina dorsally complete, reaching to hypostomal carina distinctly above base of mandible. Epomia absent. Notaulus usually long and sharp. Mesopleuron with very fine to large punctures. Median longitudinal carina of propodeum usually distinct and complete, pleural carina complete. Fore wing vein 1cu-a opposite or distal of 1-M. Areolet present, or 3rs-m absent (Gauld et al. 1997). Hind wing vein 1-cu longer than cu-a. First tergite slender, median dorsal carina absent, or vestigial or indistinct. Glymma present. Second tergite with fine, weak, or indistinct punctures. Ovipositor short, with a distinct dorsal subapical notch. Diagnosis. Apical portion of clypeus shiny, apical margin weakly and evenly concave. Outer profiles of middle and hind tibiae with distinct spines. Propodeum (Fig.  7) shagreened, area between median longitudinal carinae shiny, almost smooth; posterolateral portion with long and dense grey setae. Head, mesosoma and metasoma almost entirely black. Subbasal portions of all tibiae and median bands of middle and hind tarsi white.

Key to species of Alexeter known from China
Description. Female. Body length approximately 11.5 mm. Fore wing length 10.0 mm.
Head. Inner margins of eyes weakly indented opposite antennal sockets. Face (Fig.  2) 1.3 times as wide as long, uppermedian portion slightly convex; shagreened, with dense fine indistinct punctures; upper margin with a small median smooth tubercle. Clypeus (Fig. 2) transversely convex medially; basal portion shagreened, with indistinct short transverse wrinkle; apical portion smooth, shiny; apical margin weakly and evenly concave. Mandible with dense dark grey setae, lower tooth slightly longer than upper tooth. Malar space 0.5 times as long as basal mandibular width. Gena almost evenly convergent backward, in dorsal view approximately 0.8 times as long as width of eye. Vertex (Fig. 3) and frons with sculpture as that of face. Postocellar line 0.5 times as long as ocular-ocellar line. Antenna with 50 flagellomeres; ratios of lengths from first to fifth flagellomeres: 4.8:2.2:2.0:1.9:1.7; ultimate flagellomere twice as long as penultimate flagellomere. Occipital carina complete.
Mesosoma. Pronotum shagreened, upper portion with dense fine transverse wrinkles; hind margin of lateral concavity with short transverse oblique wrinkles. Epomia indistinct. Mesoscutum (Fig. 4) finely shagreened, with relatively sparse shallow punctures, distance between punctures mostly subequal to one diameter of puncture. Notaulus weak, present on front half of mesoscutum. Scutoscutellar groove with dense longitudinal wrinkles. Scutellum and postscutellum finely shagreened. Mesopleuron (Fig. 5) with sculpture almost as that of mesoscutum, with indistinct fine punctures. Speculum very small, upper portion shagreened. Mesopleural fovea vestigial. Upper end of epicnemial carina almost reaching anterior margin of mesopleuron, at level of upper 0.6 of pronotum. Metapleuron almost flat, with sculpture as that of mesopleuron; posterior margin with short transverse wrinkles. Submetapleural carina distinct, complete. Wings (Fig. 6) slightly infuscate. Fore wing with vein 1cu-a distal to 1-M by 0.3 times length of 1cu-a. Areolet triangular, with long petiole, 0.4 times length of its height. 2m-cu slightly reclivous, connecting to posterior angle of areolet. Hind wing vein 1-cu 1.5 times as long as cu-a. Outer profiles of middle and hind tibiae with relative dense spines. Ratio of length of hind tarsomeres from first to fifth is     4.0:2.0:1.5:0.8:1.0. Tarsal claws simple, hind claw strongly thick and curved (Fig. 8). Propodeum (Fig. 7) with distinct posterior transverse and strong complete median longitudinal carinae, latter strongly constricted medially. Area between median longitudinal carinae shiny, with indistinct, irregular transverse oblique fine striae. Area petiolaris with irregular longitudinal wrinkles. Remainder with sculpture as that of mesopleuron. Posterolateral portion with long dense grey hairs. Propodeal spiracle circular.
Coloration (Fig. 1). Black, except for the following. Apical half of clypeus, anterior side and apical portion of fore femur red brown. Dorsoposterior portion of pronotum, fore tibia, basal halves of middle and hind tibiae except bases, mid tarsomeres 3 and 4, and hind tarsomeres 2-5 white. Apicomedian portion of scutellum yellowish white. Pterostigma and wing veins brownish black.     Comparative diagnosis. The new species is similar to A. niger (Gravenhorst, 1829) in coloration: mesosoma and metasoma black; basal and apical portions of hind tibiae black, median portions white or yellowish white, but can be distinguished from the latter by the following combinations of characters: median longitudinal carina of propodeum complete, strong (absent or indistinct in A. niger); fore wing vein 2m-cu connecting to posterior angle of areolet (basad in A. niger); antenna, face and tegula black (antenna yellow-brown, face and tegula yellow in A. niger).