A new species of Xorides Latreille (Hymenoptera, Ichneumonidae, Xoridinae) parasitizing Pterolophia alternata (Coleoptera, Cerambycidae) in Robinia pseudoacacia

Abstract A new species is described, Xorides benxicus Sheng, sp. n., reared from the cerambycid twig-boring pest of Robinia pseudoacacia Linnaeus, Pterolophia alternata Gressitt, 1938, in Benxi County, Liaoning Province, China. A key is given to the species similar to Xorides benxicus Sheng, namely Xorides asiasius Sheng & Hilszczański, 2009, Xorides cinnabarius Sheng & Hilszczański, 2009 and Xorides sapporensis (Uchida, 1928).

In this article a new species of Xorides is described. The species was reared in Benxi County, Liaoning Province, at the southern border of the Eastern Palearctic part of China, as a parasitiod of Pterolophia alternata Gressitt, 1938 (Coleoptera: Cerambycidae), which bores twigs of Robinia pseudoacacia Linnaeus and is considered a pest.

Materials and methods
Rearing parasitoids. Twigs of naturally heavily infested R. pseudoacacia trees were brought to the laboratory and maintained in a large nylon cage at room temperature. Water was sprayed over the trunks and twigs twice a week and emerged insects collected daily.
Rearing parasitoid larvae and pupae. Parasitoid larvae and cocoons were collected from galleries of wood-borers in infested twigs of R. pseudoacacia and stored individually in glass tubes with a piece of filter paper dipped in distilled water to maintain moisture and plugged tightly with absorbent cotton wool.
The host was identified by Professor Wen-Kai Wang, Changjiang University, Hubei Province, China.
Images of whole insects were taken using a CANON Power Shot A650 IS. Other images were taken using a Cool SNAP 3CCD attached to a Zeiss Discovery V8 Stereomicroscope and captured with QCapture Pro version 5.1.
The morphological terminology is mostly that of Gauld (1997). Wing vein nomenclature is based on Ross (1936) and the terminology on Mason (1986Mason ( , 1990 Diagnosis. Xorides benxicus can be distinguished from the similar species of Xorides, possessing subapical terga with white apical spots in females, by the combination of the characters: head and mesosoma entirely black; face strongly convex centrally; apical part of lateral longitudinal carinae of area basalis combined; posterior part of second tergum with irregular longitudinal wrinkles; hind margins of terga 3 to 7 white, lateral parts of the white portions broken; last tergum with a smooth median longitudinal groove. Ovipositor sheath approximately 2.5 times as long as hind tibia. Flagella of male ( Figure 5) slightly compressed, apex of each flagellomere swollen, lateral and ventral-lateral profiles with erect long setae, setae approximately 3.5 times as long as width of flagellomere and curved apically.
Description. Female. Body length 5.5 to 7.5 mm. Fore wing length 4.3 to 5.5 mm. Ovipositor sheath length 4.2 to 5.5 mm.
Head. Face ( Figure 3) approximately 1.8 times as wide as long, strongly convex, with uneven, fine punctures; median portion shining, sparsely punctate; lower-lateral portion with indistinct oblique wrinkles; upper portion with median longitudinal groove; upper margin with strong median projection towards frons. Clypeal suture distinct. Clypeus with sub-basal transverse ridge; below ridge strongly inclined, weakly concave, with fine coriaceous texture. Mandible with fine median longitudinal groove; basal portion with fine longitudinal wrinkles; tooth shining. Subocular sulcus distinct. Malar space 0.6 to 0.7 times as long as basal width of mandible. Inner part of subocular sulcus shining with very sparse punctures, outer part with distinct oblique wrinkles and fine punctures. Gena in dorsal view approximately 0.7 times as long as width of eye; lower portion with longitudinal wrinkles, medially with dense punctures, upper portion smooth with very sparse and fine punctures. Vertex (Figure 4)  flagellomeres 4 to 6 strongly curved, each flagellomere at curve with 2 peg-like setae. Ratio of length from first to fifth flagellomeres: 2.9:3.5:3.7:3.9:3.9. Occipital carina complete.
Mesosoma. Anterior portion of pronotum with fine, dense punctures; lateral concavity smooth and shining, remaining portion with dense, coarse punctures; dorsal portion, neck, with three strong, forking longitudinal carinae ( Figure 6). Epomia very strong, upper end reaching to upper margin of pronotum, projecting and turned inward to dorsal centre of neck. Mesoscutum with dense, fine punctures. Middle lobe of mesoscutum (Figure 7) and anterior portion of lateral lobes with dense, distinct punctures. Mesoscutum with longitudinal wrinkles postero-medially, postero-laterally smooth and shining. Notaulus shallow, reaching 0.6 to 0.7 × distance to posterior margin of mesoscutum. Scutoscutellar groove smooth with strong median longitudinal carina. Scutellum rough, with irregular wrinkles, medially convex, subapical-medially concave. Postscutellum semicircular ridge-shaped convexity, anteriorly deeply concave. Mesopleuron (Figure 8) shining, evenly convex, with fine dispersed punctures; ventro-posteriorly with distinct transverse groove; without speculum; mesopleural fovea consisting of short, shallow horizontal groove near mesopleural suture. Upper end of epicnemial carina reaching subalar prominence. Metapleuron rough, with irregular reticulate wrinkles. Submetapleural carina complete. Wings hyaline. Fore wing with vein 1cu-a distal to 1/M by 0.25 to 0.5 × length of 1cu-a. Vein 2rs-m almost disappeared, approximately 0.15 × distance between it and 2m-cu. Vein 2-Cu approximately as long as or slightly longer than 2cu-a. Hind wing vein 1-cu approximately as long as cu-a. Legs relatively slender. Fore and mid tibiae very thick, approximately columnar, subbasal part of ventral side angularly concave. Front side of fore tibia with short spines. Hind coxa elongate, medially distinctly expanded. Claws relatively small. Propodeum rough, completely areolated. Area basalis small, triangular, apical part of lateral longitudinal carinae combined. Area superomedia pentagonal, costula connecting approximately at its middle. Area externa with oblique longitudinal wrinkles. Area dentipara with irregular transverse wrinkles. Areas superomedia and posteroexterna with vague, irregular or reticulate wrinkles. Area petiolaris with distinct longitudinal wrinkles. Propodeal spiracle small, elongate.
Metasoma. First tergum 1.7 to 1.8 × as long as apical width, rough, with weak oblique median groove from median lateral margin extending backward to posterior median part; anterior to spiracle with transverse wrinkles; medially with irregular reticulate wrinkles; posteriorly with irregular longitudinal wrinkles. Median dorsal and dorsolateral carinae present from base to spiracle. Spiracle slightly convex, at anterior 0.35 of first tergum. Second tergum approximately 0.76 × as long as apical width; anteriorly with distinct punctures, posteriorly with irregular longitudinal wrinkles; with deep oblique groove cutting off basolateral corner. Third tergum 0.55 to 0.6 × as long as apical width, with weak punctures, posteriorly with weak and indistinct transverse wrinkles. Terga 4 to 6 very short, with fine leathery texture. Last tergum in dorsal view triangular, dorsally concave, with smooth median longitudinal groove. Ovipositor sheath approximately 2.5 × as long as hind tibia. Ovipositor relatively slender, apical portion depressed. Apical part of lower valve with 7 inclivous ridges, basal 4 or 5 distinct and strong; basal of the ridges with a roughened area, length of roughened area approximately as long as distance between basal ridge and end of lower valve.
Color (Figure 1). Black, except the following: anterior profile of scape and flagellomeres 10 to 13 white. Clypeus blackish brown, along ventral margin vaguely yellowish brown. Basal portion of mandible dark red. Posterior portion of malar space with small brown spot. Fore and mid coxae (except basal portions brownish black), apical spots of fore and mid femora, main portions of anterior and posterior profiles of fore and mid tibiae, hind coxa dorsoapically, hind margins of terga 3 to 7 except dorso-lateral sides, white. Fore and mid legs irregularly dark brown. Hind trochanter, femur basally, tibia medially, tarsomere 1 (to 2) blackish brown. Apex of hind femur, both apices of hind tibia irregularly brown. Hind tarsomeres (2) 3 and 4 brown to light brown. Apical margin of tergum 1 narrowly brown. Stigma dark brown. Veins brownish black.
Male (Figure 2). Body length 5.0 to 5.2 mm. Fore wing length 3.3 to 3.4 mm. Antenna length approximately 5.5 mm. Flagellum ( Figure 5) slightly compressed, apex of each flagellomere swollen, lateral and ventral-lateral profiles with erect, long setae, setae approximately 3.5 × as long as width of flagellomere, curved apically. Stigma approximately 3.2 × as long as width. Antenna entirely black. Terga entirely black, or second tergum and apex of first tergum more or less blackish brown.
Host. Pterolophia alternata Gressitt, 1938. Host plant. Robinia pseudoacacia L. This new species is similar to X. asiasius Sheng & Hilszczański, 2009, X. cinnabarius Sheng & Hilszczański, 2009and X. sapporensis (Uchida, 1928, possessing subapical terga with white spots on apical part in females; flagellomeres with perpendicular hairs about as long as or longer than diameter of flagellomere, stigma short and wide, approximately or less 3x as long as wide, first tergum with oblique median groove running from median lateral margin extending backward to posterior median portion in male (X. asiasius unknown). It can be distinguished from them by the following key.