Lathrobium scaphiforme, Assing, 2015

Assing, Volker, 2015, New species and additional records of Lathrobium and Elytrobium from the Palaearctic region, with special reference to the fauna of East Yunnan (Coleoptera: Staphylinidae: Paederinae), Beiträge Zur Entomologie = Contributions to Entomology 65 (1), pp. 41-74 : 69

Lathrobium scaphiforme spec. nov.

( Figs 119–125 )

Type material: Holotype : “ JAPAN, Honshu, Iwate, Kawai, Yoshibezawa [39°37'N, 141°31'E], 600–700 m, 16. VIII.91, A. Smetana [J57] / Holotypus  Lathrobium scaphiforme spec. nov., det. V. Assing 2014” ( CNC).

Paratype  [teneral]: “ JAPAN, Honshu, Iwate, Kawai, Zaimokuzawa , 720 m, 15. VI.91, A. Smetana [J54]” (cAss) .

Etymology: The specific epithet is an adjective composed of the Latin noun scapha (boat) and the suffix -forme. It alludes to the boat-shaped dorsal plate of the aedeagus.

Description: Body length 8.3–9.0 mm; length of forebody 4.4 mm. Habitus as in Fig. 119 . Coloration: body blackish; legs pale-brown; antennae dark-brown.

Head ( Fig. 120 ) transverse, 1.04–1.07 times as broad as long; punctation moderately coarse and rather dense, sparser in median dorsal portion; interstices with distinct microreticulation. Eyes weakly projecting from lateral contours of head, approximately one-third as long as postocular region in dorsal view and composed of approximately 50 ommatidia. Antenna 2.3 mm long.

Pronotum ( Fig. 120 ) approximately 1.2 times as long as broad and about as broad as head; punctation similar to that of head, but somewhat sparser; impunctate midline moderately broad; interstices without microsculpture.

Elytra ( Fig. 120 ) short, approximately half as long as pronotum, weakly dilated posteriad; humeral angles weakly marked; punctation shallow and moderately dense; interstices without microsculpture. Hind wings completely reduced. Protarsomeres I–IV with pronounced sexual dimorphism.

Abdomen distinctly broader than elytra; punctation fine and moderately dense, density decreasing towards posterior tergites; posterior margin of tergite VII without palisade fringe.

: protarsomeres I–IV strongly dilated; sternite VII ( Fig. 121 ) strongly transverse, with impression of subtriangular shape in postero-median portion, this impression with moderately dense short black setae, posterior margin distinctly concave in the middle; sternite VIII ( Fig. 122 ) weakly transverse and longitudinally impressed in postero-median portion, posterior excision U-shaped, on either side of posterior excision acutely produced and with a dense cluster of stout black setae; aedeagus ( Figs 123–125 ) 1.9 mm long and symmetric; ventral process long, weakly curved in lateral view, with a long median carina ventrally, subapically with a pair of tooth-like processes; dorsal plate with a long, distinctly sclerotized and dorsally excavate apical portion and with an even longer lamellate basal portion; internal sac with a broad, curved (cross-section), and moderately sclerotized structure.

: protarsomeres I–IV moderately dilated, distinctly less so than in male; sternite VIII longer than tergite VIII, convexly produced posteriorly; tergite IX with long and undivided antero-median portion and short posterolateral processes; tergite X short, approximately half as long as antero-median portion of tergite IX.

Comparative notes: The similarly modified male sternites VII and VIII, as well as the similar general morphology of the aedeagus suggest that L. scaphiforme is allied to L. pollens SHARP, 1889 and related species. It differs from L. pollens by the differently shaped pronotum (more slender and less strongly tapering posteriad), the more strongly transverse male sternite VII with a more distinctly modified chaetotaxy, the shape and chaetotaxy of the male sternite VIII (more pronounced clusters of modified setae on either side of the posterior excision; posterior excision narrower), and by the structure of the aedeagus (ventral process differently shaped, subapically dentate; dorsal plate much more massive and of different shape; presence of a large internal structure). For characters separating it from the syntopic L. volutum , the only other micropterous Lathrobium species recorded from Iwate Prefecture, see the comparative notes in the following section.

Distribution and natural history: The type material was collected in two localities near Kawai (northern Honshu: Iwate Prefecture) at altitudes between 600 and 720 m. The paratype is distinctly teneral.

Figures

Figs 111–125: Lathrobium oharai WATANABE and L. scaphiforme spec. nov. (119–125) habitus (111–119); forebody (112, 120); male sternite VII (113, 121); male sternite VIII (114, 122); aedeagus in lateral and in ventral view (115–116, 123–124); female sternite VIII (117); female tergites IX–X (118); apical portion of aedeagus in dorsal view (125). Scale bars: 111–112, 119–120: 1.0 mm; 113–118, 121–125: 0.5 mm.