Lathrobium biexcisum, Assing, 2013

Assing, V., 2013, On the Lathrobium fauna of Japan (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 45 (1), pp. 1615-1641 : 1621-1623

Lathrobium biexcisum nov.sp. ( Figs 7-12 )

T y p e m a t e r i a l Holotype 3: "Gumma Pref., Nikko distr. , L. Maranuma [recte: Marunuma] / 1430-1500 m., 11-12.viii.80 / JAPAN: Honsu, B.M. 1980-492, P.M. Hammond / Holotypus 3 Lathrobium biexcisum sp.n., det. V. Assing 2013" ( BMNH).

E t y m o l o g y: The specific epithet (adjective) alludes to the posterior excisions of both the male sternite VII and the male sternite VIII.

D e s c r i p t i o n: Species of large size; body length 11.5 mm; length of forebody 5.1 mm. Habitus as in Fig. 7 . Coloration: body dark-brown; legs reddish; antennae reddish.

Other external characters ( Fig. 8 ) as in L. pollens . 3: protarsomeres I-IV strongly dilated; tergite VIII with very weakly convex posterior margin; sternites III-VI unmodified; sternite VII ( Fig. 9 ) distinctly transverse, posteriorly with pronounced median impression, this impression with moderately dense black setae; posterior margin with distinct and broad concavity in the middle, lateral margins of this concavity furnished with dense and long dark setae; sternite VIII ( Fig. 10 ) weakly transverse, posterior excision of nearly semi-circular shape, margin of this excision and posterior median impression furnished with dense dark setae, posterior margin on either side of posterior excision acutely produced; aedeagus ( Figs 11-12 ) 2.5 mm long and symmetric; ventral process slender, weakly curved in lateral view, subapically abruptly narrowed, and apically needle-shaped, ventrally with pair of long and pronounced carinae; dorsal plate very long, slender, lamellate, and apically acute, basal portion longer than apical portion; internal sac without sclerotized structures.

♀: unknown.

C o m p a r a t i v e n o t e s: The similar external and the similarly derived male sexual characters suggest that L. biexcisum is closely allied to L. pollens , from which it is distinguished by the less deep posterior excision of the male sternite VII and by the different shape of the slightly smaller aedeagus. The aedeagus is most similar to that of L. nasuense WATANABE 1992 , which was described from the environs of Nasu in the northeast of Tochigi Prefecture. From this species, L. biexcisum differs by the broader posterior excision of the male sternite VIII and by the different shape of the ventral process of the aedeagus in lateral view (straight basal portion shorter).

D i s t r i b u t i o n: The type locality is situated in the northeast of Gunma Prefecture, Honshu, at an altitude of 1430-1500 m.

Figures

Figs 7-12: Lathrobium biexcisum nov.sp.: (7) habitus; (8) forebody; (9) male sternite VII; (10) male sternite VIII; (11-12) aedeagus in lateral and in ventral view. Scale bars: 1.0 mm.