﻿A new species of Trychosis Förster (Hymenoptera, Ichneumonidae, Cryptinae), with a key to the species known from China

﻿Abstract A new species of Ichneumonidae, Trychosisnaolihense Meng & Ren, sp. nov., is described and illustrated. Specimens were collected from Naolihe National Natural Reserve, Heilongjiang Province, China. A key to the currently known species from China is provided.

The Western Palaearctic species of Trychosis were revised by van Rossem (1966van Rossem ( , 1971van Rossem ( , 1990. Townes and Townes (1962) studied the Nearctic species and provided a key to the known species from this region. Prior to this study, there was neither a key nor a revision of the Eastern Palaearctic species, only three species of Trychosis, T. indigna (Kokujev, 1909), T. legator (Thunberg, 1822), and T. yezoensis (Uchida, 1930), were known from China (Kokujev 1909;Sheng and Sun 2014;Sheng et al. 2016).
Since 2021, a survey to the insect resources has been conducted in the Naolihe National Natural Reserve, Heilongjiang, which aims to track and document the biodiversity of this area. During this survey, a new species of Trychosis was collected and discovered in Naolihe Reserve. The primary purpose of this study is to describe and illustrate this new species and provide a key to the currently known species from China.

Materials and methods
Specimens were collected using sweeping nets from emerged plants at the Hongqiling farm (46°51′26"N, 133°1′50"E) in Naolihe National Natural Reserve, Heilongjiang. The predominant plant families in this area are Cyperaceae and Gramineae, with Carex pseudocuraica and Calamagrostis angustifolia as dominant species.
Morphological terminology mostly follows Broad et al. (2018). The type specimen of the new species is deposited in the Center for Biological Disaster Prevention and Control, National Forestry and Grassland Administration (CB-DPC). The description and measurements were made under a Leica M205A stereomicroscope with LAS Montage MultiFocus. Diagnosis. Fore wing length 3.2-8.8 mm. Clypeus moderately to strongly convex, with anterior margin almost truncate to strongly convex forward, without tooth. Mesoscutum very short, with dense punctures. Epomia usually present and strong. Epicnemial carina reaching center of mesopleuron close to its anterior margin. Propodeum strongly oblique, anterior and posterior transverse carinae present. Propodeal spiracle almost circular. Areolet usually parallel laterally. Hind wing with vein 1-cu as long as or longer than cu-a. Tergite 1 long, 0.5-0.6× as long as mesosoma. Ovipositor thin, compressed, with nodus.

Key to species known from China (females)
Notes. Trychosis indigna (Kokujev, 1909) is not included in the key because only one male specimen is known. It is distinguished from other species in the key by the following combination of characters: complete posterior transverse carina of propodeum; frons with median carina; infumated wings; posterior portion of tergite 1-3 entirely brown.  (Fig. 2) distinctly long, 1.2× as wide as long, with dense, weak, transverse wrinkles. Areolet pentagonal, convergent anteriorly, 3rs-m shorter than 2rs-m. Head, mesosoma, and tergites 1-5 entirely black, tergites 6-7 yellowish white medially and black laterally.
Head. Face (Fig. 2) 1.2× as long as wide, slightly convex medially; lateral margin almost parallel; dorsal portion with dense fine punctures, ventral portion with indistinct, short, transverse wrinkles; dorsal margin evenly concave medially. Clypeus (Fig. 2) 1.2× as wide as long, with dense, weak, transverse wrinkles,   and fine, sparse, indistinct punctures laterally; subventral margin depressed. Mandibles with dense, obscure rugae; dorsal tooth as long as ventral tooth. Malar space rough, 0.8× as long as basal width of mandible. Gena (Figs 3, 4) strongly convergent in dorsal view, in lateral view approximately 0.4× as long as width of eye, with dense fine punctures. Vertex (Fig. 4) with indistinct fine punc-tures, denser on posteromedian part. Stemmaticum slightly convex, irregularly rugulose. Postocellar line approximately 1.3× as long as ocular-ocellar line. Frons with median longitudinal carina (Fig. 5), dorsal part with dense, indistinct punctures, ventral part smooth, shiny. Antenna stout, with 23 flagellomeres; ratio of length from the first to the fifth flagellomeres approximately: 6.1: 6.4: 5.7: 4.8: 4.5. The first flagellomere 4.5× as long as its maximum width. Occipital carina complete and strong, with the ventral end joining the hypostomal carina slightly posterior to the base of mandible.
Mesosoma. Lower part of propleuron (Fig. 6) smooth and shiny in lateral view, with short, transverse wrinkles along ventral posterior margin; pronotum with oblique wrinkles medially, with dense, fine punctures posteriorly in dorsal view. Epomia present and short. Mesoscutum slightly convex and weakly punctate, anterior part of notauli present. Scutellum evenly convex, with dense, fine punctures, laterally with indistinct, short, longitudinal wrinkles; anterior part 0.2 with lateral carina. Postscutellum shiny, transverse posteriorly, anterior part concave, laterally with deep pit. Mesopleuron (Fig. 6) with dense punctures; distance between punctures 0.2-2.5× diameter of a puncture. Speculum small, smooth. Upper end of epicnemial carina reaching mid part of pronotum, distant to anterior margin of mesopleuron. Mesosternum with dense fine punctures, and short indistinct wrinkles near epicnemial carina. Metapleuron (Fig. 7) with dense punctures; distance between punctures 0.2-0.5× diameter of a puncture; ventral posterior part with oblique transverse wrinkles. Juxtacoxal carina absent. Posterior spur of hind tibia longer than anterior spur, reaching to the middle of the first tarsomere. Ratio of length of hind tarsomeres from the first to the fifth approximately: 9.0: 3.5: 2.4: 1.7: 2.3. Wings (Figs 1, 8) slightly gray, hyaline. Fore wing with vein 1cu-a almost interstitial M&RS. Areolet pentagonal, convergent anteriorly, receiving vein 2m-cu in the middle, 3rs-m shorter than 2rs-m. 2m-cu distinctly reclivous. Postnervulus intercepted at about lower 1/4. Hind wing vein 1-cu 1.9× as long as cu-a. Propodeum (Fig. 9) with anterior carina complete and strong; posterior carina present laterally; the anterior part between the anterior margin and the anterior carina shiny and almost smooth; posterior part rough, with dense, indistinct, fine punctures. Propodeal spiracle small, transversely elliptical.
Etymology. The specific name is derived from the type locality.   (Telenga, 1930) in having gena that almost straightly converge backwards (Figs 3, 4); anterior part of scutellum with lateral carina; anterior part of propodeum between anterior margin and anterior carina smooth and shiny; head, mesosoma, and tergites 1-5 entirely black. The female of this new species can be distinguished from T. nigra by the combination of the following characters: fore wing with vein 1cua interstitial with vein M&RS, the maximum width of areolet at most equal to its height, hind wing with vein 1-cu distinctly longer than cu-a; legs entirely black except for basal 0.75 of the hind femur red; tergites 5-6 yellowish white dorsally. Whereas the females of T. nigra have the fore wing with vein 1cu-a distinctly postfurcal to M&RS; width of areolet distinctly wider than its height, hind wing vein 1-cu shorter than cu-a; the fore and middle legs with the femora apically and the tibiae entirely red, the hind leg with the tibia basally red and the femur entirely black; tergites entirely black.