Orsunius granulosus, Assing, 2014

Assing, V., 2014, On Orsunius II. Eight new species and additional records (Coleoptera: Staphylinidae: Paederinae: Medonina), Linzer biologische Beiträge 46 (1), pp. 461-479 : 471-472

Orsunius granulosus nov.sp. ( Figs 26-32 , Map 2 )

Type material: Holotype: " Laos: Champasak prov.: Bolaven Plt, Muang Paxong, Ban Hoyayteuy , Mt. Phu Din , 13-14.vi.2008; 1100 m, 15°03.171'N 106°17.397'E / A. Solodovnikov & J. Pedersen leg., Disturbed primary rainforest, sifted leaf litter; ZMUC collection / Holotypus Orsunius granulosus sp.n. det. V. Assing 2012" ( ZMUC) . Paratypes: 3, 3: same data as holotype ( ZMUC, cAss) ; 4, 3: " Vietnam-N, Quang Binh prov., 1 km N of Cha Lo, 400 m, Vietnam-Laos border area , 17°41'22''N, 105°45'45''E, L. Dembický leg., 11.-24.iv.2010 " ( NHMB, cAss) ; 2: " THAILAND - river near Ban Pong Din, 32 km ENE Chiang Mai, 27.XI.2004, leg. W. Rossi" (cAss).

Etymology: The specific epithet (Latin, adjective) refers to the granulose punctation of the pronotum.

Description: Body length 3.7-4.2 mm; length of forebody 1.9-2.1 mm. Habitus as in Fig. 26 . Coloration: body reddish to dark-brown, with the elytra sometimes slightly paler and the elytral postero-lateral angles weakly infuscate; legs yellowish to yellowishbrown; antennae reddish.

Head ( Fig. 27 ) of transversely rectangular shape, approximately 1.15 times as broad as long; posterior margin distinctly concave in the middle; punctation distinct and dense; interstices narrower than diameter of punctures and glossy, without microsculpture; sides with long dark-brown setae. Eyes large, on average approximately as long as postocular portion in dorsal view, often slightly shorter or longer. Antennae slender, 1.1-1.2 mm long; preapical antennomeres approximately as wide as long. Anterior margin of labrum with broadly V-shaped excision in the middle; left mandible with three, right mandible with four pronounced molar teeth.

Pronotum ( Fig. 27 ) approximately 1.2 times as wide as long and 1.05 times as broad as head; posterior angles rounded, weakly marked; lateral and anterior margins with long dark setae; punctation very dense and distinctly, finely granulose, rendering the pronotum matt; with or without rudiment of an impunctate median band in posterior half.

Elytra ( Fig. 27 ) 1.10-1.15 times as long as pronotum; punctation very dense, fine, and somewhat asperate. Hind wings fully developed. Protarsomeres I-IV sexually dimorphic, more distinctly dilated in males than in females. Metatarsomere I longer than II and slightly shorter than the combined length of II and III.

Abdomen narrower than elytra; punctation extremely fine and dense, barely noticeable in the microsculpture; posterior margin of tergite VII with palisade fringe.

: sternite VII ( Fig. 28 ) with weakly concave posterior margin; sternite VIII ( Fig. 29 ) oblong and with posterior excision of trapezoid shape ( Fig. 30 ); aedeagus ( Figs 31-32 ) small, approximately 0.35 mm long; internal sac with a pair of strongly sclerotized short and curved apical structures and with a pair of longer, less strongly sclerotized basal structures.

Comparative notes: This and the two following species are attributed to Orsunius with some hesitation. They share the habitus, the head shape, and other external characters with the species previously assigned to the genus, but are distinguished from them by the presence of four (rather than three) molar teeth on the right mandible, the broadly V-shaped median incision of the anterior margin of the labrum, the conspicuous granulose punctation of the pronotum, and by a rather different morphology of the aedeagus. From the closely related O. cuneatus and O. heissi , O. granulosus is best distinguished by the trapezoid posterior excision of the male sternite VII and by the morphology of the aedeagus.

Distribution and natural history: The species is known from three localities in southern Laos, North Thailand, and North Vietnam ( Map 2 ). The partly teneral specimens from Laos were sifted from leaf litter in a degraded primary forest at an altitude of 1100 m.

Figures

Map 2: Distributions of Orsunius gladiator (white and black circles), O. latexcisus (black circle), O. flavovirgatus (black circle), O. heissi (black star), O. stimulans (black and grey triangles), O. granulosus (white and grey triangles), O. cuneatus (white diamond), and O. spathulatus (black square).

Figs 26-35: Orsunius granulosus nov.sp. (26-32), O. latexcisus nov.sp. (33) and O. flavovirgatus nov.sp. (34-35): (26) habitus; (27) forebody; (28) male sternite VII; (29, 33, 34) male sternite VIII; (30, 35) posterior portion of male sternite VIII; (31) aedeagus in lateral view; (32) aedeagus in ventral view. Scale bars: 26-27: 1.0 mm; 28-29, 31-34: 0.2 mm; 30, 35: 0.1 mm.