A new species of genus Syntactus Förster (Hymenoptera, Ichneumonidae, Ctenopelmatinae) with a key to Oriental and Eastern Palearctic species

Abstract A new species, Syntactus jiulianicus Sun & Sheng, sp.n. belonging to the tribe Pionini of the subfamily Ctenopelmatinae (Hymenoptera, Ichneumonidae), collected from Jiangxi Province, China, is reported. Illustrations of the new species and Syntactus delusor (Linnaeus, 1758), Syntactus minor (Holmgren, 1857) and Syntactus varius (Holmgren, 1858) are provided. A key to the species of Syntactus known from the Oriental and Eastern Palaearctic Regions is given.


Introduction
Syntactus Förster, 1869, belonging to the tribe Pionini of the subfamily Ctenopelmatinae (Hymenoptera, Ichneumonidae), comprises six described species (Horstmann 2007, Kasparyan and Khalaim 2007, Yu et al. 2005, all of them distributed in the Palaearctic Region, three of which are from the Eastern Palearctic.
In this article a new species belonging to Syntactus, collected in Jiangxi Province, situated at the northern border of the Oriental part of China, are reported.
The morphological terminology is mostly that of Gauld (1991). Wing vein nomenclature is based on Ross (1936) and the terminology on Mason (1986Mason ( , 1990 Ovipositor thin, needle-like, straight or slightly upcurved. Diagnosis. Syntactus jiulianicus can be distinguished from all other species of Syntactus by the combination of the face and clypeus smooth and shining, sparsely and finely punctuate; gena and frons impunctate; face, mesopleuron and mesosternum yellow; first to third terga of female reddish brown, male yellow.  Mesosoma. Anterior portion of pronotum smooth, lateral concavity with dense oblique fine wrinkles, dorsal-porsterior portion with fine punctures. Epomia present, weak. Mesoscutum with dense and fine punctures. Notauli present, anterior 0.3 sharp. Scutoscutellar groove with weak longitudinal wrinkles. Scutellum convex, with fine punctures, basal 0.3 with lateral carina. Postscutellum weakly convex, approximately quadrate. Subalar prominence strongly convex. Mesopleuron (Figure 3) and metapleuron smooth and shining. Lower portion of mesopleuron with sparse and indistinct fine punctures. Epicnemial carina strong, upper end reaching subalar prominence. Posterior portion of metapleuron with fine oblique wrinkles. Submetapleural carina strongly, anterior portion evidently convex. Wings slightly brownish, hyaline, apical portions smoky-gray. Fore wing with vein 1cu-a distal of 1/M by 0.2 times as long as 1cu-a. Vein 2-Cu approximately 1.8 times as long as 2cu-a. Hind wing vein 1-cu about 1.5 times as long as cu-a. Apical edge of fore tibia with a small tooth at outer side. Hind coxa smooth, with sparse and fine punctures. Ratio of length of hind tarsomeres 1:2:3:4:5 is 5.3:2.7:1.9:1.1:1.4. Propodeum (Figure 4) evenly convex. Area basalis slightly longer than wide, smooth, convergent anteriorly. Area superomedia longer than wide, costula connecting in front of its middle, combined with area petiolaris, combined area smooth, nearby apical margin with distinct transverse fine wrinkles, from costula to apex evidently convergent posteriorly. Area externa with fine punctures and gray hairs. Area lateralis with dense oblique wrinkles. Pleural carina distinctly curved at the level of propodeal spiracle, with carina between pleural carina and propodeal spiracle. Propodeal spiracle approximately 2.6 times as long as wide.

Key to species of Syntactus Förster known in Oriental and Eastern Palaearctic Regions
Metasoma. Terga almost smooth. First tergum approximately 2.3 times as long as apical width, strongly convergent toward base, median dorsal carinae indistinct.
Dorsolateral carinae weak, subbasal portion near spiracle indistinct. Ventrolateral carinae complete. Spiracle convex, located slightly before middle of first tergum. Second tergum trapeziform, approximately 0.7 times as long as apical width. Third tergum approximately 0.5 times as long as apical width. Ovipositor sheath approximately 0.7 times as long as apical depth of metasoma, subapical portion distinctly wider than basal portion (Figure 6). Ovipositor very thin.  Color. (Figure 1). Main body and legs yellow, except the following. Flagellum reddish brown. Apical teeth of mandibles, vertex, collar, mesoscutum, lateral portions of scutellum and postscutellum, axillary troughs of mesonotum and metanotum, a small spot beneath subalar prominence, fourth to seventh terga except narrow hind margins black. Median portions of scutellum and postscutellum red. Propodeum darkish brown, lateral portion fuscous. Terga 1 to 3 reddish brown. Posterior-lateral portions of third and fourth terga with longitudinal brownish black spots. Metapleuron and hind legs reddish brown. Stigma blackish brown. Veins dust-colored.