Trisunius scaphiformis, Assing, 2015

Assing, Volker, 2015, A revision of Trisunius V. Three new species and additional records, including the first records of the genus from Vietnam (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 47 (2), pp. 1179-1190 : 1184-1186

Trisunius scaphiformis nov.sp. ( Figs 1-6 )

T y p e m a t e r i a l: Holotype 3: " THAILAND [1] - Doi Inthanon , Maeaum, 18°32' N, 98°31'E, 1560 m, sifted near stream, 18.XII.2013, leg. Ob / Holotypus 3 Trisunius scaphiformis sp.n. det. V. Assing 2015" (cAss).

E t y m o l o g y: The specific epithet (Latin, adjective, from scapha = boat) alludes to the shape of the ventral process of the aedeagus in ventral view, which som ewhat resembles the outline of a boat.

D e s c r i p t i o n: Body length 3.1 m m; length of forebody 1.7 mm. Habitus as in Fig. 1 . Coloration: head and pronotum brown; elytra dark-brown with the hum eral and posterior portion diffusely paler; abdom en dark-brown; legs pale yellowish-brown; antennae reddish.

Head ( Fig. 2 ) 1.05 tim es as long as broad; lateral margins behind ey es subparallel in dorsal view; punctation fine and dense; intersti ces with distinct m icroreticulation. Eyes weakly protruding from lateral contours of head approxim ately 0.7 tim es as long as postocular region in dorsal view. Antenna 0.9 mm long.

Pronotum ( Fig. 2 ) 1.07 tim es as long as broad and approxim ately as broad as head; lateral margins weakly converging posteriad in dorsal view; punctation fine and dense, somewhat more distinct than that of head; m idline very narrowly impunctate; interstices with shallow microsculpture.

Elytra ( Fig. 2 ) long, 1.07 tim es as long as pronotum; punctation fine and dense; interstices without microsculpture. Metatarsomere I approximately as long as II.

Abdomen slightly narrower than ely tra; punctation very fine and very dense; interstices with distinct m icroreticulation; posterior margin of tergite VII with palisade fringe; posterior margin of tergite VIII strongly convex.

3: sternite VII ( Fig. 3 ) moderately transverse, pubescence not distinctly modified, posterior margin weakly convex in the m iddle; sternite VIII ( Fig. 4 ) weakly transverse, posterior excision nearly 0.3 tim es as deep as length of sternite; aedeagus ( Figs 5-6 ) 0.45 mm long; ventral process slender, lateral margins somewhat folded ventrad subapically.

C o m p a r a t i v e n o t e s: This species is characterized particularly by the distinctive shape of the ventral process of the aedeagus. It is additionally separated from the syntopic T. spathulatus by the longer and weakly bicoloured elytra, by the unmodified pubescence of the m ale sternite VII, and by the less deep and differently shaped posterior excision of the male sternite VIII. For illustrations of T. spathulatus and other Trisunius species see ASSING (2011, 2012, 2013, 2014).

D i s t r i b u t i o n a n d n a t u r a l h i s t o r y: The type locality is situated in Doi Inthanon, North Thailand. The holotype was sifted from leaf litter and debris near a stream at an altitude of 1560 m, together with T. spathulatus and T. conlectus (see the following section).

Figures

Figs 1-6: Trisunius scaphiformis nov.sp.: (1) habitus; (2) forebody; (3) male sternite VII; (4) male sternite VIII; (5-6) aedeagus in lateral and in ventral view. Scale bars: 1: 1.0 mm; 2: 0.5 mm; 3-4: 0.2 mm; 5-6: 0.1 mm.