Genus Acantholabus Heinrich, 1974

Acantholabus Heinrich, 1974: 157–158. Type species: Acantholabus malaisei Heinrich, 1974 by original designation.

Diagnosis

Female antenna slender, bristle-shaped, with elongate basal flagellar segments, not widened beyond middle, with a white ring. Male antenna with distinct, elongate tyloids. Eye rather large. Gena short. Vertex abruptly sloping just behind ocelli. Temples short, sharply and roundly narrowed behind the eyes. Occipital carina with dorsal impression which does not reach level of eyes or hind ocelli. Clypeus strongly convex, weakly separated from middle field of face. Mandibles gradually narrowed, dorsally and ventrally carinated. Pronotum without carina interrupting transverse furrow. Upper margin of pronotum not thickened. Pronotal base gradually and uniformly curved. Mesoscutum rather strongly convex, almost as long as broad, very densely punctured. Notauli visible only at anterior third of mesoscutum. Mesoscutum matt. Subtegular ridge thick and sharp. Sternaulus weakly impressed at front half. Scutellum uniformly raised, laterally and apically carinate with high, sharp carinae, its horizontal part flat. Hind margin of metanotum with teeth. Horizontal part of propodeum in middle distinctly shorter than area petiolaris. Lateral propodeal carina indistinct, if present, situated at middle of area superomedia. Area dentipara short, with longer or short but distinct denticular apophysis. Juxtacoxal carina distinct. Propodeal spiracle relatively large, elongate, oval. Legs rather long and slender. Hind coxa elongate. Fore wing with areolet rather large, quadrangular, and symmetrical. Vein R straight and long. Vein 1cu-a interstitial. T1 petiole thick, strongly flattened at base. Gastrocoeli weakly impressed and elongate. Thyridia large and broad, distant from base of T2, with rather narrow interval between them with weak impression. Hypopygium relatively large, roughly triangular in outline, without distinct longitudinal fold. Ovipositor sheath slightly projecting behind apex of metasoma.

Remarks

This genus resembles Dentilabus, but can be distinguished by the following characters: male flagellum with distinct tyloids (usually absent in Dentilabus); horizontal part of scutellum flat (usually convex in Dentilabus); T2 with weak median longitudinal impression between thyridia. Dentilabus iyoensis Kikuchi & Konishi, 2018 is an exception, as it shares these characteristics with Acantholabus (Kikuchi & Konishi 2018). The generic position of this species should be reconsidered in future studies.

Key to species of Acantholabus Heinrich, 1974

1. Propodeum with short tooth-like protrusions (Fig. 7E). Temple long, 0.7× as long as width of eye (Fig. 7B–C). Hind coxa black (Fig. 6). T5–7 with narrow white hind margins (Fig. 7G) ................. ................................................................................................................ A. regressus Heinrich, 1974

– Propodeum with elongate apophysis (Figs 3D, 5F, 9E). Temple short, 0.3–0.4× as long as width of eye (Figs 5B–C, 9B–C). Hind coxa reddish-brown (Figs 2, 3D, 4, 8). T6–7 with broad white hind margins (Figs 2, 3C, 5G–H) .............................................................................................................. 2

2. T1–2 with broad ivory apical margins (Figs 2, 3C). Scutellum with tooth-like lateral protrusions (Fig. 3D). Area superomedia short ....................................................... A. furciliatus Heinrich, 1974

– T1–2 without yellowish colouration (Figs 4, 5G–H, 8, 9C, I). Scutellum without tooth-like lateral protrusions (Fig. 5D). Area superomedia elongate (Fig. 5E) ........................................................... 3

3. Propodeum with large curved apophysis, slightly elongate (Fig. 5E–F). Sternaulus distinctly impressed (Fig. 4). T1 with lateral carina (Fig. 5G–H), petiole elongate, 1.9× as long as postpetiole (in profile). Body mostly dark (Fig. 4). Scape ventrally brownish-black (Fig. 5A). Face and clypeus black medially and yellowish laterally (Fig. 5A). Pronotum mostly black, with narrow ventral and dorsal margins (Fig. 5B) .......................................................................... A. malaisei Heinrich, 1974

– Propodeum with small straight apophysis, short (Fig. 9E). Sternaulus vestigial (Fig. 9G). T1 without lateral carina, petiole short (Fig. 9C), 1.6 × as long as postpetiole (in profile). Body mostly pale (Fig. 8). Scape ventrally reddish-yellow (Fig. 9A). Face and clypeus mostly yellowish-white, (narrowly black medially) (Fig. 9A). Pronotum mostly white, with small dorsal-lateral pale reddish stripe (Fig. 9B) ........................................................ A. yunlingensis Reshchikov & Kikuchi sp. nov.