﻿Two new Palaearctic species of Xynobius Foerster (Hymenoptera, Braconidae, Opiinae)

﻿Abstract Two new and very similar species of the genus Xynobius Foerster, 1863 are described and illustrated, X.subparallelus Han & van Achterberg, sp. nov. from Japan (Honshu) and X.setosiscutum van Achterberg, sp. nov. from Norway. Three species are newly reported from Norway: Xynobiusaciculatus (Thomson, 1895), X.comatus (Wesmael, 1835), and X.polyzonius (Wesmael, 1835). X.polyzonius (Wesmael, 1835) and X.sapporanus (Fischer, 1963) are new combinations. Identification keys to the Xynobius species known from Norway and Japan are added.


Introduction
Opiinae is a large subfamily of the family Braconidae with approximately 2,000 valid species and 39 genera according to Yu et al. (2016). It is a common group of parasitoid wasps containing mainly mining or fruit-infesting dipterous larvae and has a worldwide distribution. Wharton (e.g. 1987Wharton (e.g. , 1988Wharton (e.g. , 1997 published important updates and some additions for the existing keys to the genera of Opiinae, but the number of genera remains a matter of discussion because the limits of some genera, especially of Opius Wesmael, 1835 and Eurytenes Foerster, 1863, are uncertain. We follow Li et al. (2013) and treat the genus Xynobius Foerster, 1863 as a valid genus separate from Opius Wesmael, 1835, not included within it as was done in the past.
During a visit to Osaka Museum of Natural History the first author discovered a remarkably setose species from Japan (Honshu), and the second author discovered a similar species from south-west Norway among Malaise-trap material. These new taxa are compared, described, and illustrated below.

Material and method
The Japanese specimen was collected by using a sweep net. The Norwegian specimens were collected in a Malaise trap and were chemically treated with a mixture of xylene + alcohol 96% and amylacetate (AXA-method; van Achterberg 2009). For identification of the subfamily Opiinae, see van Achterberg (1990Achterberg ( , 1993Achterberg ( , and 1997; for references to the Opiinae, see Yu et al. (2016).
Morphological terminology follows van Achterberg (1988van Achterberg ( , 1993, including the abbreviations for the wing venation. Measurements are taken as indicated by van Achterberg (1988); for the length and the width of a body part the maximum length and width is taken, unless otherwise indicated. The length of the mesosoma is measured from the anterior border of the mesoscutum up to the apex of the propodeum and of the first tergite from the posterior border of the adductor up to the medio-posterior margin of the tergite.
Observations, photographic images, and descriptions were made either under a digital stereo microscope (VHX-1000, Keyence) or with a Canon 5Ds 50.6-megapixel camera combined with a Canon MP-E 65 mm f/2.8 1-5× macro lens, Laowa KX-800 macro twin flash, and an electronic WeMacro Z-stepper rail. The photos were stacked with Helicon Focus v. 7 software (HeliconSoft, Kharkiv, Ukraine).

Genus
Description. Female; length of body 2.7 mm, of fore wing 2.6 mm and of antenna about 3.4 mm.
Legs. Length of hind femur 5.3× longer than its width (Fig. 11). Metasoma. Length of first tergite 1.8× longer than its apical width, its surface rugose with longitudinal striae and rather flat in lateral view (Fig. 5); dorsope distinctly present (Figs 5,9); second tergite finely and irregularly longitudinally striate medially ( Fig. 6) and distinctly longer than third tergite; second metasomal suture absent (Fig. 6); following tergites smooth and with few setae posteriorly; length of setose part of ovipositor sheath 0.5× longer than length of first tergite and nearly 0.1× as long as fore wing, slightly protruding beyond apex of metasoma ( Fig. 1).
Remarks. The new species has a distinct dorsope, symmetric mandible, vein r much shorter than vein 2-SR and a large hypoclypeal depression; therefore, it belongs to the genus Xynobius. Most important is the slender (subparallel-sided) first metasomal tergite, the irregularly and weakly longitudinally striate second tergite, the entirely setose mesoscutum and the reduced notauli (absent on most of mesoscutal disc and only distinct and crenulate anteriorly). In the key by Tobias (1998), this species runs to the subgenus Apodesmia Foerster sensu Tobias and (surprisingly) to O. (Opius) angusticellularis Tobias, 1998. This species has little to do with the new species because the mesosoma is only slightly longer than high in lateral view, the second and third metasomal tergites are granulate and the antenna has 22-24 segments. The new species runs in Chen and Weng (2005) to Opius (Apodesmia) isabella Chen & Weng, 2005, but it belongs to the genus Apodesmia Foerster, 1863 because the occipital carina is connected to the hypostomal carina ventrally, the second and third tergites are more or less coriaceous, and the clypeus is only 1.2× wider than long. Actually, the new species is similar to Xynobius wengi van Achterberg & Li, 2013 because of the setose mesoscutum and scutellum and striate second metasomal tergite. However, X. wengi has the crenulate notauli present on the mesoscutal disc (only apical quarter absent; notauli nearly entirely absent on disc in X. subparallelus), vein m-cu of the fore wing postfurcal or subinterstitial (distinctly antefurcal in X. subparallelus), the first metasomal tergite about 1.3× longer than wide apically (about 1.8× in X. subparallelus), and the second tergite regularly and coarsely striate (irregularly and finely striate X. subparallelus). Diagnosis. Antenna with 32-34 segments, flagellum dark brown but apical segments more or less brown; temple medium-sized ( Fig. 19; roundly narrowed and eye in dorsal view 2.6× longer than temple); mesoscutum and scutellum evenly and conspicuously setose (Fig. 15); notauli largely absent on mesoscutal disc (a derived character state in common with X. subparallelus sp. nov. from Japan); hind femur comparatively robust (Figs 12, 17; about 4× longer than wide); pterostigma narrow elliptical and gradually narrowed apically (Fig. 13); vein m-cu of fore wing distinctly antefurcal and posteriorly angulate with vein 2-CU1 (Fig. 13); first tergite distinctly widened posteriorly ( Fig. 16; 1.2-1.4× longer than its apical width in ♀, about 1.6× longer in ♂); second tergite regularly and costate-like striate (Fig. 16) and third tergite smooth; setose part of ovipositor sheath shorter than first metasomal tergite (Fig. 17) and at most slightly protruding beyond apex of metasoma. The new species is very similar to X. subparallelus sp. nov. from Japan because of the reduction of the notauli and the conspicuous setosity of the mesoscutum and scutellum. However, it differs by having the first tergite distinctly widened posteriorly (subparallel-sided in X. subparallelus), distinctly wider temple (comparatively narrow), apex of third and fourth metasomal tergites yellow (blackish or dark brown), second tergite regularly and coarsely striate (finely and irregularly striate) and hind femur less slender, about 4× longer than wide (more robust, about 5× longer than wide).
Remarks. This species runs to the subgenus Allotypus Foerster sensu Fischer, and with difficulty to Opius saevulus Fischer, 1958 (mesosoma less than 1.5× longer than high in lateral view) or O. irregularis Wesmael, 1835 (mesosoma 1.5× longer than high in lateral view), in the keys by Fischer (1972). Both of these species have nothing in common with the new species and both belong to the genus Apodesmia Foerster, 1863 because the occipital carina is curved and connected to hypostomal carina. Actually, the new species is more related to X. aciculatus (Thomson, 1895) because they share the setose middle lobe of the mesoscutum, the striate second tergite, the (at least partly) yellow face and clypeus, and the comparatively robust first tergite in females. The new species has the lateral mesoscutal lobes largely setose medially (glabrous in X. aciculatus); vein 3-CU1 of fore wing distinctly longer than vein CU1b (about of equal length); vein r of fore wing widened and shorter (narrow and longer); antenna of ♀ with 32-34 segments (with 28-31 segments); sixth metasomal tergite yellow largely dark brown); second tergite coarsely striate (finely striate); notauli largely absent on mesoscutal disc (notauli complete on disc); and vein m-cu of fore wing antefurcal (postfurcal).