First records of the genus Gnathochorisis Förster (Hymenoptera, Ichneumonidae, Orthocentrinae) in the Oriental region

Oriental members of the genus Gnathochorisis Förster, 1869 (Ichneumonidae: Orthocentrinae) are reviewed, two species: G. leleji sp. nov. from Malaysia and G. malaisei sp. nov. from Myanmar, are described and illustrated. The genus Gnathochorisis is recorded from the Oriental region for the first time.


Introduction
Gnathochorisis Förster, 1869 is a moderately small genus of Darwin wasps of the subfamily Orthocentrinae. It was established by A. Förster with the type species Gnathochorisis flavipes Förster, 1871 from Germany, together with two other genera: Blapticus Förster, 1869and Laepserus Förster, 1869(Förster 1869. Subsequently some Blapticus species were transferred to the genus Acroblapticus Schmiedeknecht, 1911 established for Gnathochorisis species excluding G. flavipes (Schmiedeknecht 1911). Later Acroblapticus and Laepserus were synonymized with Gnathochorisis (Aubert 1966(Aubert , 1969, and Blapticus species were divided between Gnatnochorisis and Symplecis Förster, 1869(van Rossem 1981. Western Palaearctic species of Gnathochorisis were revised by van Rossem (1981Rossem ( , 1987; three more species have been described from the Eastern Palaearctic (Humala 2007;Humala et al. 2016;Watanabe 2020). In North America, this genus has been revised by Dasch (1992); he reported eight species of the genus for the Nearctic, two of them with Holarctic distribution. Seven species of this genus were described from the Neotropics (Humala 2017). This genus has also been reported from the Philippines (Baltazar 1964) and Australia (Gauld 1984), but these materials were not examined by the author of this study. At present no species have been described from these regions, as well as from the Afrotropical region, where this genus also occurs, although the species diversity there can be comparable with the Neotropics. In total, Gnathochorisis comprises 23 described species (Yu et al. 2016;Humala 2017;Watanabe 2020).
The aim of this work is to describe two new Oriental species of Gnathochorisis, representing first records of the genus for this region.

Materials and methods
The specimens examined in this study are deposited in the following collections: MZLU Zoological Museum, Lund University, Sweden; NHRS Naturhistoriska Riksmuseet, Stockholm, Sweden; ZISP Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia.
Morphological terminology follows Broad et al. (2018). Specimens were examined using a Leica MZ9.5 stereomicroscope. Photographs were taken with an Olympus OM-D digital camera attached to an Olympus SZX10 stereomicroscope at ZISP; partially focused images were combined using Helicon Focus Pro software (v. 7.6.6). Diagnosis. Gnathochorisis can be distinguished from other orthocentrine genera belonging to the tribe Helictini by the following combination of characters: body stout; scape subcylindrical, elongate, not inflated, and its hind margin of apical truncation not membranous; male flagellum lacking tyloids; female inner orbits subparallel or slightly divergent downwards; sternaulus short; propodeum usually with complete carinae; fore wing with sessile or shortly petiolate areolet, if areolet absent, then vein 2rs-m moderately long; hind femur stout; hind claws enlarged; first metasomal segment petiolate, its tergite and sternite fused and glymmae absent. Together with Symplecis, Catastenus Förster, 1869 andEusterinx Förster, 1869, Gnathochorisis forms the so-called Eusterinx-group (Wahl 1990;Wahl and Gauld 1998). This monophyletic group can be distinguished from other orthocentrines by the fused tergite and sternite of the first segment of metasoma, absence of glymmae, and mostly complete carination of the propodeum. Gnathochorisis differs from Catastenus and Symplecis in having ovipositor upcurved, with a dorsal subapical notch, 0.5-1.1 times as long as hind tibia, and female inner orbits subparallel or slightly divergent downwards. Gnathochorisis species can be distinguished from Eusterinx by stout body, transverse head and nervellus intercepted in lower half. Diagnosis. Gnathochorisis leleji sp. nov. can be distinguished from the majority of species of the genus by the lack of closed areolet. From the other two similar known species without areolet (G. flavipes and G. fuscipes Humala & Lee, 2016), the new species differs in the strongly transverse head, and stronger apophyses on propodeum. From the East Palaearctic G. fuscipes, the new species differs in having a narrow face with width 0.45 times head width at the level of antennal sockets (0.51-0.53 times in G. fuscipes), slenderer flagellum with first flagellomere about 4.7 times as long as wide (3.9 times in G. fuscipes), predominantly yellow hind legs (hind coxa dark brown in G. fuscipes), and a shorter ovipositor -0.8 times as long as first tergite (as long as first tergite in G. fuscipes). From the Palaearctic G. flavipes it differs in lack of yellowish posterior band on T2 (present in G. flavipes) and inclivous nervellus (almost vertical in G. flavipes). The new species is also characterized by the unique semicircular formation with reticulate microsculpture of T4 of male metasoma, not known in other congeners.
Head. Head width 1.25 times its height; face width at level of antennal sockets 1.7 times its height, 0.45 times head width, subpolished and closely punctate with long sparse setae; frons, vertex and occiput matt; occipital carina present; eyes large, convex, without setae, inner orbits slightly divergent ventrally (Fig. 2); clypeus width 1.6 times its height, weakly separated from face, with posterior margin truncate; anterior tentorial pits distinct; malar space 1.8 times as long as basal width of mandible; subocular sulcus nearly straight; mandibles bidentate, tapered, lower tooth shorter than upper tooth (Fig. 2). Antenna long, with 21 flagellomeres, scape long, subcylindrical, about 2.3 times as long as wide; first flagellomere 4.4-4.7 times as long as wide apically, second flagellomere 3.5-3.6 times as long as wide apically. Head strongly transverse, temple very short; ocelli of moderate size, ocular-ocellar line 1.1 times as long as maximum diameter of lateral ocellus; postocellar line 1.3 times as long as maximum diameter of lateral ocellus (Fig. 3).
Metasoma. First metasomal segment 1.6 times as long as its maximum posterior width, postpetiole with dorsal carinae and irregular longitudinal striae; dorso-lateral carina distinct, extending above spiracle; glymma absent, spiracle situated at 0.5 length of first tergite, apex of first sternite at 0.4 of segment; T2 0.8 times as long as its maximum posterior width, with small indistinct first thyridium and more conspicuous second thyridium behind the middle, longitudinally striate in anterior 3/4, subpolished in posterior 1/4 (Fig. 5). Remaining tergites subpolished; sternites membranous with sclerotized patches on S2 to S7. Ovipositor upcurved with dorsal subapical notch, ovipositor sheath 0.8 times as long as first tergite and 0.75 times as long as hind tibia.
Etymology. The new species is named in honour of Prof. Arkady S. Lelej -a well-known Russian entomologist, in recognition of his significant contribution to the study of Hymenoptera, and also in celebration of his 75 th birthday.

Gnathochorisis malaisei
This species resembles the Neotropical G. dilleri Humala, 2017 in the elongate area superomedia of propodeum, but it can be easily distinguished by the presence of lateral sections of anterior transverse carina, stouter hind femur (4.0 times as long as broad), yellow face and dark mesoscutum and propodeum.
Description. Female. Body length 4.2 mm; fore wing length 3.5 mm. Head. Head width 1.7 times its height; face width at level of antennal sockets 1.35 times its height, 0.5 times head width, subpolished and closely punctate; frons, vertex and occiput polished; occiput somewhat depressed, occipital carina present; eyes large, convex, without setae, inner orbits subparallel (Fig. 10); clypeus width 1.5 times its height, weakly separated from face, posterior margin of clypeus very weakly convex; anterior tentorial pits distinct; malar space 1.2 times as long as basal width of mandible; subocular sulcus distinct, sharp and straight; mandible bidentate, strongly tapered, lower tooth small (Fig. 10). Antenna longer than body, with 23 slender flagellomeres, all flagellomeres longer than wide; scape about twice as long as wide; first flagellomere 5.3 times as long as wide apically, second flagellomere 4.4 times as long as wide apically. Ocelli of moderate size, ocular-ocellar line 1.25 times and postocellar line 0.6 times as long as maximum diameter of lateral ocellus (Fig. 11); temple moderately short, 0.35 times as long as compound eye width.
Metasoma. First metasomal segment 2.5 times as long as maximum width posteriorly, T1 subpolished, with distinct dorsal carinae reaching posterior margin; sternite and tergite fused, glymma absent, spiracle situated at basal 0.4 length of T1, apex of first sternite at 0.55 of segment. T2 as long as maximum width posteriorly, coriaceous, with small thyridium and some irregular longitudinal striae in anterior 2/3, subpolished in posterior third (Fig. 13); in profile T2 transversely impressed in the middle behind spiracles; remaining tergites nearly impunctate. Ovipositor slightly upcurved with dorsal subapical notch, ovipositor sheath 1.2 times as long as first tergite and 0.7 times as long as hind tibia.
Male. Unknown. Etymology. The new species is named in honor of its collector René Malaise, a Swedish hymenopterist, expert on sawflies (Hymenoptera: Symphyta), famous for his invention of the "Malaise trap".
Kazuhiko Konishi, Andrew Bennett, Andrey I. Khalaim, Janko Kolarov and Vladimir Gokhman, who provided useful criticism and valuable comments, for reviewing and editing the manuscript. This work was carried out under a state order implemented by Forest Research Institute KarRC RAS.