Trisunius discrepans, Assing, 2011

Assing, V., 2011, Trisunius gen. nov. from the southern East Palaearctic and the Oriental regions (Coleoptera: Staphylinidae: Paederinae: Medonina), Linzer biologische Beiträge 43 (1), pp. 195-220 : 205-207

Trisunius discrepans nov.sp. ( Figs 27-33 )

T y p e m a t e r i a l: Holotype Ƌ: " China: Yunnan [CH07-03], Dali Bai Auton. Pref., Diancang Shan W Dali, 25°41'49''N, 100°06'24''E, 2970 m, sifted at rock edges and under small shrubs, 28.V.2007, M. Schülke / Holotypus Ƌ Trisunius discrepans sp.n. det. V. Assing 2011" (cAss). Paratypes: 4 exs.: same data as holotype (cSch); 11 exs.: same data, but "leg. A. Pütz" (cPüt, cAss); 6 exs. [1♀ macropterous]: " China: Yunnan, Dali Bai Auton. Pref., Diancang Shan W Dali, 25°41'52''N, 100°06'28''E, 2960 m, along path, sifted from litter, moss, flood debris, 6.IX.2009, leg. M. Schülke [CH09-31]" (cSch, cAss); 2 exs.: " China (N-Yunnan) Dali Bai Nat. Aut. Pref., Diancang Shan, 4 km W Dali old town, 2900-3000 m, 25°41.4'N, 100°06.7'E, E slope, former stone pit (in overgrown gravel, soil, plant roots) 31.VIII.2003 Wrase [20]" (cSch); 1 ex.: " China (N-Yunnan) Dali Bai Nat. Aut. Pref., Diancang Shan, 4 km W Dali old town, 2900-3000 m / 25°41.4'N, 100°06.7'E, E slope, former stone pit (in overgrown gravel, soil, plant roots, und. stones) 18.VI.2005 D.W. Wrase [12]" (cSch); 5 exs.: " China (Yunnan) Nujiang Lisu Aut. Pref., Gaoligong Shan, side valley 18 km NW Liuku, 2590 m, 25°58'10''N, 98°42'27''E (devast. prim. forest, litter sifted) 9.-10.VI.2007 D.W. Wrase [29]" (cSch, cAss); 1♀: " China: N-Yunnan [C2005- 12], Nujiang Lisu Aut. Pref., Gongshan Co., Gaoligong Shan, 2500 m, 27°45.404'N, 98°35.749'E, litter & debries [sic] at snowfield sifted during rain, 19.VI.2005, M. Schülke" (cSch); 2♀♀: same data, but "[C2005-12A] ... 21.VI.2005 " (cSch, cAss).

D e s c r i p t i o n: Relatively large and mostly dark-coloured species; body length 3.2-4.0 mm. Habitus as in Fig. 27 . Coloration: head and pronotum dark-brown to blackish, with the pronotum usually slightly paler than head; elytra reddish-brown to blackishbrown; abdomen blackish-brown to blackish; legs and antennae reddish; rarely whole body almost uniformly reddish.

Head approximately as wide as long (micropterous morph) or weakly oblong (macropterous morph), weakly dilated (micropterous morph) or subparallel (macropterous morph) in dorsal view ( Figs 28-29 ); punctation fine, dense, and shallow; interstices with very shallow to distinct microreticulation. Eyes small, approximately one third as long as postocular region in dorsal view (micropterous morph), or larger and more than half as long as postocular region in dorsal view (macropterous morph). Anterior margin of labrum with two distinct teeth on either side of median incision.

Pronotum ( Figs 28-29 ) approximately 1.1 times as long as wide and 0.95 times as wide as head, widest anteriorly (micropterous morph) or approximately in the middle (macropterous morph); punctation rather fine and dense; midline with narrow impunctate band; interstices in anterior, lateral, and posterior portions often with shallow traces of microsculpture, in median dorsal portion without microsculpture.

Elytra conspicuously dimorphic; in micropterous morph very short, 0.70-0.75 times as long as pronotum, somewhat widened posteriorly, and with weakly pronounced humeral angles ( Fig. 28 ), in macropterous morph approximately 1.2 times as long as pronotum, with subparallel lateral margins, and with pronounced humeral angles ( Fig. 29 ); punctation dense, fine, shallow, and weakly defined; interstices without microsculpture. Hind wings completely reduced (micropterous morph), or fully developed (macropterous morph). Metatarsomere I approximately as long as II.

Abdomen much broader (micropterous morph) or much narrower (macropterous morph) than elytra, widest at segment VI; punctation fine and dense on anterior and less dense on posterior tergites; interstices with distinct microsculpture; posterior margin of tergite VII in micropterous morph with fine, in macropterous morph with pronounced palisade fringe.

Ƌ: sternite VII posteriorly impressed in the middle, on either side of this impression with extensive cluster of long dark setae, posterior margin weakly concave in the middle ( Fig. 30 ); sternite VIII with moderately deep and rather broad posterior excision ( Fig. 31 ); sternite IX as in Fig. 32 ; aedeagus rather large, at least approximately 0.50 mm long, with apically acute ventral process of characteristic shape and with distinctive internal structures ( Fig. 33 ).

I n t r a s p e c i f i c v a r i a t i o n: This species is subject to a remarkable dimorphism, this dimorphism not only affecting the length of the elytra and the hind wings, but also the shape of the head, the size of the eyes, the shape of the pronotum, and the palisade fringe at the posterior margin of the abdominal tergite VII. The only macropterous specimen examined is a female, so that the possibility that it is not conspecific with the other type specimens cannot be ruled out with absolute certainty. However, the macropterous female is similar to the micropterous morph in many external characters and it was found together with several micropterous specimens, suggesting that it refers to the same species. Moreover, the localities in the Diancang Shan and the Gaoligong Shan are separated by a considerable distance, suggesting that there is a winged morph. Finally, a similarly pronounced dimorphism was observed also in T. cultellatus .

E t y m o l o g y: The specific epithet (Latin, present participle of the verb discrepare) alludes to the remarkable dimorphism (see above).

C o m p a r a t i v e n o t e s: This species is characterized particularly by its relative large body size, dark coloration, the conspicuously short elytra of the micropterous morph, the very long elytra of the macropterous morph, as well as by the male primary and secondary sexual characters.

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: Trisunius discrepans is known from several localities in the Diancang Shan and the Gaoligong Shan in western Yunnan, China. The specimens were sifted from litter, moss, and debris in forests, under shrubs, in a former stone pit, and near snowfields at altitudes of 2500-3000 m in May, June, and September. On no occasion was T. discrepans collected with other species of the genus.

Figures

Figs 27-33: Trisunius discrepans nov.sp.: (27) habitus (micropterous morph); (28) forebody (micropterous morph); (29) forebody (macropterous morph); (30) male sternite VII; (31) male sternite VIII; (32) male sternite IX; (33) aedeagus in lateral view. Scale bars: 27: 1.0 mm; 28-29: 0.5 mm; 30-32: 0.2 mm; 33: 0.1 mm.