Xynobius subparallelus Han & van Achterberg, 2023

Han, Yunjong, van Achterberg, Cornelis, Lee, Heung-Sik & Kim, Hyojoong, 2023, Two new Palaearctic species of Xynobius Foerster (Hymenoptera, Braconidae, Opiinae), ZooKeys 1160, pp. 61-74 : 61

Xynobius subparallelus Han & van Achterberg sp. nov.

Type material.

Holotype, ♀ (OMNH), "Japan: Naihara, Totsukawa, Yoshino District, 34°05'49"N, 135°52'20"E, 11.viii.2013, SW [= collected by sweeping], Shunpei Fujie, OMNH"

Diagnosis.

This species belongs to the Xynobius comatus group on account of the evenly and conspicuously setose middle lobe of the mesoscutum and scutellum (Figs 3 , 4 ), but it differs from all other species by the subparallel-sided first tergite (Fig. 5 ; about 1.8 × longer than its apical width), short temple (Fig. 8 ; eyes in dorsal view about 2.1 × longer than temple), irregularly and weakly striate second tergite (Fig. 6 ), and vein m-cu of the fore wing that gradually merges into vein 2-CU1 (Fig. 2 , but this character is rather variable in X. setosiscutum ). In addition, the notauli are largely absent on the mesoscutal disc (Fig. 4 , a derived character state in common with X. setosiscutum sp. nov. from Norway), and the second tergite is longitudinally striate (Fig. 6 ).

Description.

Female; length of body 2.7 mm, of fore wing 2.6 mm and of antenna about 3.4 mm.

Head. Antenna with 33 segments (Fig. 10 ), 1.2 × longer than body; margin of antennal sockets strongly protruding, depression between antennal sockets (Fig. 7 ); length of eye in dorsal view 2.1 × longer than temple (Fig. 8 ); height of head 1.35 × longer than height of eye; vertex and frons punctate, setose except for large, smooth interspaces on vertex; no median keel on frons (Fig. 7 ); width of clypeus twice longer than its maximum height; hypoclypeal depression large (Fig. 7 ); length of the maxillary palp 1.4 × longer than height of head; malar sulcus absent; occipital carina absent dorsally; mandible robust (Fig. 1 ), symmetric, gradually widened basally.

Mesosoma. Length of mesosoma 1.4 × longer than its height (Fig. 3 ); pronope absent but with transverse crenulated groove (Fig. 4 ); mesopleuron largely smooth, but precoxal sulcus medially impressed and coarsely crenulate (Fig. 3 ); mesopleural sulcus largely smooth; notauli absent on disc except for a pair of short, deep impressions anteriorly (Fig. 4 ); mesoscutum and scutellum shiny, punctulate, and densely setose; medio-posterior depression of mesoscutum round and rather small (Fig. 4 ); scutellar sulcus medium-sized and distinctly crenulate; scutellum flat and only posteriorly narrowly sculptured; propodeum reticulate-rugose, with short medio-longitudinal carina anteriorly but posteriorly largely smooth between carinae (Figs 5 , 9 ).

Wings. Fore wing (Fig. 2 ): pterostigma narrow elliptical, gradually narrowed apically; vein 1-SR+M sinuate; vein 2-SR distinctly oblique; vein 3-SR 1.7 × longer than vein 2-SR; vein SR1 slightly curved; r:3-SR:SR1 = 4:26:46; vein m-cu distinctly antefurcal; second submarginal cell elongated; first subdiscal cell transverse and elongated (Fig. 2 ). Hind wing: vein m-cu oblique and only pigmented; vein 1r-m 0.5 × as long as vein 1-M.

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 ).

Colour. Generally dark brown dorsally (Fig. 1 ); head, scape, mesopleuron and pronotum, yellowish brown; legs and palpi, pale brownish yellow.

Distribution.

Japan (Honshu).

Biology.

Unknown.

Etymology.

Named after the subparallel-sided first metasomal tergite; " sub " is Latin for "less than" and " parallelus " is Latin for "equidistantly sides".

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 Opius 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 ).

Figures

Figure 1. Xynobius subparallelus Han & van Achterberg, sp. nov., holotype, ♀, Japan, habitus, lateral.

Figures 2 - 11. Xynobius subparallelus Han & van Achterberg, sp. nov., holotype, ♀, Japan 2 wings 3 mesosoma lateral 4 mesosoma dorsal 5 propodeum and 1 st metasomal segment dorsal 6 2 nd and following metasoma segments dorsal 7 head anterior 8 head dorsal 9 propodeum posterior and 1 st metasomal segment basal 10 antenna 11 hind leg lateral. The arrow indicates the dorsope.