A new species of genus Rhinotorus Förster (Ichneumonidae, Ctenopelmatinae) parasitizing Pristiphora erichsonii (Hymenoptera, Tenthredinidae) and a key to Eastern Palaearctic species

A new species of Ctenopelmatinae, Rhinotorus nigrus Sheng, Li & Sun, sp. nov. reared from cocoons of Pristiphora erichsonii (Hartig) in Jilin Province, China, is described and illustrated. A key to Eastern Palaearctic species of Rhinotorus is provided.

The species of Rhinotorus Förster were revised by Reshchikov (2016). Prior to the present study the genus has not been recorded in China, nor from the Oriental Region.
The diagnostic characters of Rhinotorus were described by Townes (1970) and expanded upon by Reshchikov (2016).
Nineteen host species of Rhinotorus from ten genera of Tenthredinidae have been recorded, 17 of them belong to subfamily Nematinae (Yu et al., 2016). In the present research parasitism of the genus Rhinotorus Förster, 1869 Pristiphora erichsonii (Hartig) is recorded for the first time. Images were taken using a Leica M205A stereo microscope with LAS Montage MultiFocus. Morphological terminology is mostly based on Broad et al. (2018). Type specimens are deposited in the Insect Museum, GSFGPM.

Key to the Eastern Palaearctic species of Rhinotorus
Description. Body length 6.0-7.0 mm. Fore wing length 6.0-6.5 mm.
Head. Inner orbits parallel. Face (Fig. 2) approximately 1.9 × as wide as long, slightly evenly convex, lateral portion shagreened, upper-median portion with distinct punctures; lower-median portion with indistinct punctures; upper margin with median small tubercle. Clypeus approximately 2.4 × as wide as long, smooth, shiny, with sparse shallow indistinct punctures, apical median portion convex; median section of apical margin distinctly depressed. Basal portion of mandible with dense indistinct punctures; upper tooth sharper and slightly longer than lower tooth. Malar area and vertex (Fig. 4) shagreened. Malar space approximately 0.5 × as long as basal width of mandible. Postocellar line approximately same length as ocular-ocellar line. Gena (Fig. 3) with fine punctures. Frons (Fig. 5) slightly convex medially, with dense fine punctures. Antenna with 31 flagellomeres; ratio of length from first to fifth flagellomeres approximately: 6.5:4.0:3.5:3.5:3.0. Occipital carina reaching hypostomal carina slightly above base of mandible.
Metasoma. First three tergites (Fig. 8) with dense punctures. Subposterior portions of first and second tergites with weak transverse depressions. First tergite approximately 0.8 × as long as posterior width, with irregular short wrinkles; dorsal median carina reaching to 0.6 length of first tergite; dorsolateral and ventrolateral carinae complete; postpetiole strongly convex; spiracle small, circular, convex, located approximately at anterior 0.4 of first tergite. Second and third tergites (Fig. 8) approximately 0.5 × as long as posterior width. Fourth and subsequent tergites with relatively sparse fine punctures. Ovipositor sheath (Fig. 9) approximately 2.3 × as long as its maximum width, from middle evenly narrowed posteriorly.

Differential diagnosis
The new species is similar to Rh. jussilai Reshchikov, 2016, but can easily be distinguished from it by the following combinations of characters: occipital carina reaching hypostomal carina slightly above base of mandible; area petiolaris of propodeum with strong median longitudinal carina; hind femur black. Rhinotorus jussilai: occipital carina reaching hypostomal carina distinctly above base of mandible; area petiolaris of propodeum without median longitudinal carina; hind femur brownish red.

Discussion
The new species is the only species of Rhinotorus recorded in the southeastern part of the Eastern Palearctic Region. The genus is not recorded in this part of Russia, in Korea and Japan. Nevertheless in the collections from the boreal and oriental part of China there are unidentified species of this genus. Rhinotorus need in further taxonomical research.