Orsunius prolongatus, Assing, 2011

Assing, V., 2011, Orsunius gen. nov. from the Oriental region (Coleoptera: Staphylinidae: Paederinae: Medonina), Linzer biologische Beiträge 43 (1), pp. 221-244 : 236-238

Orsunius prolongatus nov.sp. ( Figs 57-69 )

T y p e m a t e r i a l: Holotype Ƌ: " Indonesia, Bali, Batukaru, 700 m, Laub, 09.06.1994, P. Wunderle / Holotypus Ƌ Orsunius prolongatus sp.n. det. V. Assing 2011" (cAss). Paratypes: 2♀♀: same data as holotype (cWun).

D e s c r i p t i o n: Relatively small species; body length 3.7-4.3 mm. Coloration: forebody pale, dark-yellowish to reddish-yellow; abdomen reddish to pale reddish-brown, with the apical portions of segments VII and VIII yellowish; legs and antennae yellowish.

Head moderately transverse, 1.15-1.20 times as broad as long ( Fig. 57 ); posterior margin almost truncate, very indistinctly concave in the middle; punctation coarse and sparse ( Fig. 58 ); interstices glossy, in most of dorsal surface broader than diameter of punctures; sides with relatively few long dark-brown setae. Eyes relatively small, shorter than postocular portion in dorsal view. Antenna with preapical antennomeres very weakly transverse. Gular sutures separated by a distance greater than the width of antennomere III. Anterior margin of labrum weakly concave ( Fig. 59 ) to distinctly incised in the middle; mandibles long and slender ( Figs 60-61 ); apical maxillary palpomere long ( Fig. 62 ); labium and ligula as in Figs 63-64 .

Pronotum relatively weakly transverse, 1.05-1.10 times as wide as long and approximately 1.05 times as broad as head ( Fig 57 ); posterior angles rounded, weakly marked; lateral margins visible in posterior two thirds of lateral margin, in anterior third concealed when viewed from above; lateral margins with few long setae; punctation somewhat denser and slightly less coarse than that of head; midline broadly impunctate ( Fig. 65 ).

Elytra short, 0.85-0.90 times as long as pronotum ( Fig. 57 ); punctation very dense, shallow, fine and somewhat ill-defined; interstices without microsculpture. Hind wings present. Tarsi slender; protarsomeres I-IV strongly dilated; metatarsomere I longer than II and slightly shorter than the combined length of II and III.

Abdomen approximately as wide as elytra; punctation extremely fine and dense, slightly less dense on posterior tergites; interstices with distinct microsculpture; posterior margin of tergite VII with palisade fringe.

Ƌ: sternite VII unmodified; sternite VIII posteriorly elongated, much longer than broad, posterior portion without pubescence; posterior margin shallowly concave in the middle ( Fig. 66 ); aedeagus 0.63 mm long, not distinctly asymmetric ( Figs 67-68 ); ventral process slender and bent dorsad in lateral view, apically with two fine processes ( Fig. 69 ); internal sac with apical sclerotized structures of characteristic shape.

C o m m e n t: In one of the paratypes, the labrum is only shallowly concave in the middle ( Fig. 59 ). Since only three type specimens are available, it is difficult to say if this is a teratological malformation or an expression of normal intraspecific variation. In any case, it shows that the shape of the labrum, which has been attributed particular importance in the taxonomy of Paederinae and many other Staphylinidae , may be subject even to intraspecific variation.

E t y m o l o g y: The specific epithet (Latin, adjective) refers to the shape of the male sternite VIII.

C o m p a r a t i v e n o t e s: This species is characterized particularly by the sparse punctation of the head, the long apical maxillary palpomere, the long and slender mandibles, the small eyes, the weakly transverse pronotum, the short elytra, slender tarsi, strongly dilated protarsomeres I-IV, the strongly elongated and posteriorly non-pubescent male sternite VIII, as well as by the shape of the aedeagus (ventral process, apical internal structures). In external appearance, it is most similar to O. pravus , from which it is easily distinguished by the smaller eyes and the much more strongly dilated protarsomeres I-IV alone.

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 near lake Batukaru in Bali, Indonesia, where the specimens were sifted from forest leaf litter at an altitude of 700 m. One of the paratypes is apparently somewhat teneral.

Figures

Figs 57-69: Orsunius prolongatus nov.sp.: (57) forebody; (58) median dorsal portion of head; (59) labrum (paratype); (60-61) left and right mandible; (62) maxillary palpus; (63) labium; (64) ligula; (65) median dorsal portion of pronotum; (66) male sternite VIII; (67) aedeagus in lateral view; (68) apical portion of aedeagus in ventral view; (69) apex of ventral process in lateral view. Scale bars: 57: 0.5 mm; 58, 65-68: 0.2 mm; 59-64: 0.1 mm; 69: 0.05 mm.