Othius arater, Assing, 2018

Assing, Volker, 2018, A revision of Othiini. XX. Two new species of Othius, the first record of the genus from Myanmar, and additional records (Coleoptera: Staphylinidae: Staphylininae), Linzer biologische Beiträge 50 (1), pp. 25-40 : 31-37

Othius arater nov.sp. ( Figs 8-14 , 24-26 )

T y p e m a t e r i a l: Holotype ♂: " CHINA, S-Sichuan, road 56 km E Xichang-Zhaojue, Mt. WenLin pass, 3200 m, ~ 27°52'N, 102°30'E, 5.-20.VI.2017, leg. Reuter / Holotypus ♂ Othius arater sp. n. det. V. Assing 2017 " (cAss). Paratypes: 6♂♂, 4♀♀: same data as holotype (cFel, cAss).

E t y m o l o g y: The specific epithet (Latin, noun: plow) alludes to the distinctive shapes of the internal lateral structures of the aedeagus.

D e s c r i p t i o n: Measurements (mm) and ratios (range, arithmetic mean; n = 11): HL: 1.59-1.86, 1.70; HW: 1.49-1.83, 1.60; PW: 1.59-1.86, 1.70; PL: 1.95-2.29, 2.08; EL: 0.95-1.07, 1.00; TiL: 1.31-1.46, 1.39; TaL: 1.07-1.16, 1.11; TL: 10.4-13.1, 12.2; HL/HW: 1.02-1.10, 1.06; HW/PW: 0.89-0.98, 0.94; PL/PW: 1.17-1.28, 1.22; EL/PL: 0.44-0.51, 0.48; TaL/TiL: 0.77-0.84, 0.80.

Moderately large species (see measurements). Habitus as in Fig. 8 . Coloration: body black; legs brown to dark-brown; antennae dark-brown to blackish, sometimes with the basal antennomeres slightly paler.

Head weakly oblong, more or less distinctly wedge-shaped, i.e., more or less distinctly widened posteriorly, and somewhat narrower than pronotum (see ratios HL/HW and HW/PW); anterior pair of frontal punctures distinct, with additional smaller punctures; posterior pair of frontal punctures usually present, but often indistinct or indistin- guishable from other punctures, rarely completely absent; median dorsal portion impunctate; remaining punctation variable, usually rather fine, moderately dense to sparse, very sparse or partly absent in median dorsal portion; integument with distinct and fine isodiametric microreticulation. Eyes ( Fig. 9 ) small, approximately one-third as long as postocular region in dorsal view. Antenna 2.8-3.1 mm long; antennomeres V-X transverse.

Pronotum ( Fig. 10 ) moderately oblong (see ratio PL/PW), broadest near anterior angles, and distinctly tapering posteriorly; punctation pattern similar to that of most other East Palaearctic congeners, except for the presence of clusters of more or less numerous punctures in the antero-lateral portions and near the posterior angles; posterior discal puncture (i. e., puncture near posterior angle) distinctly separated from posterior angle by a distance of often more than three times its diameter and usually accompanied by additional punctures; microsculpture fine and predominantly composed of transverse meshes of variable length.

Elytra ( Fig. 11 ) barely half as long as pronotum (see ratio EL/PL); punctation rather sparse and shallow; interstices on average approximately twice as broad as diameter of punctures, with pronounced, but glossy microsculpture. Hind wings absent.

Abdomen slightly broader than elytra; punctation fine and rather dense; interstices with fine microsculpture predominantly composed of long transverse meshes; posterior margin of tergite VII without palisade fringe.

♂: protarsomeres I-IV strongly dilated; sternites V-VI unmodified; sternite VII shallowly impressed in postero-median portion; sternite VIII with shallow median impression posteriorly and with truncate posterior margin; posterior processes of hemitergites IX short, just reaching posterior margin of tergite X, apically without tooth-like processes; sternite IX ( Fig. 12 ) anteriorly deeply bifid, posterior margin with V-shaped excision, postero-lateral angles without spine-like processes; aedeagus ( Figs 13-14 ) 1.70-1.85 mm long; parameres apically dilated, each with 4 apical setae; internal sac ( Figs 24-26 ) with five sclerotized internal structures (basal median structure absent): a rather short and apically acute apical median and two pairs of lateral structures, the internal pair stout and of highly distinctive shape and the external pair slender and of similar length as the internal pair.

♀: protarsomeres I-IV distinctly dilated, but less so than in male.

C o m p a r a t i v e n o t e s: Othius arater is distinguished from all its congeners by the internal structures of the aedeagus, particularly the shapes of the stout lateral structures. It additionally differs from other micropterous species (without a palisade fringe at the posterior margin of tergite VII) recorded from South Sichuan as follows:

from O. excisus ASSING, 1999 (Luoji Shan to the south of Xichang) by darker coloration of the elytra and the antennae ( O. excisus : elytra dark reddish-brown; antennae reddish), a less oblong and distinctly wedge-shaped head, smaller head and pronotum, a less distinct posterior pair of frontal punctures, the microsculpture of the pronotum ( O. excisus : predominantly composed of isodiametric meshes), shorter elytra with distinct microsculpture and with much sparser and much less distinct punctation, finer punctation on the abdomen, shorter and apically less acute posterior processes of the male sternite IX, and a more slender aedeagus with internal structures of different shapes; from O. sculptipennis ASSING, 1999 (environs of Muli/Bowa) by smaller body size, the coloration ( O. sculptipennis : elytra reddish), much shorter antennae ( O. sculptipennis : antenna approximately 4 mm long; antennomeres V and VI not transverse), a much more oblong and distinctly wedge-shaped head, the microsculpture of the pronotum ( O. sculptipennis : composed of isodiametric meshes), slightly shorter elytra with less dense punctation and with different microsculpture ( O. sculptipennis : microsculpture predominantly composed of very dense micropunctures), and a smaller, apically less acute aedeagus ( O. sculptipennis : aedeagus approximately 2.1 mm long) without a basal median structure and with apical and lateral structures of different shapes.

For illustrations of O. excisus and O. sculptipennis see ASSING (1999a, 2003a).

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 to the east of Xichang in the south of the Chinese province Sichuan at an altitude of 3200 m. The specimens were collected with pitfall traps in subalpine bushland with rhododendron, small pine, and moist meadows (REUTER pers. comm.).

Figures

Figs 8-14: Othius arater: (8) male habitus; (9) head in lateral view; (10) pronotum in dorso-lateral view; (11) elytra; (12) male sternite IX; (13-14) aedeagus in lateral and in ventral view. Scale bars: 8-10: 1.0 mm; 11-14: 0.5 mm.

Figs 24-29: Othius arater (24-26) and O. burmensis (27-29): (24-26) internal structures of aedeagus in ventral view; (27-28) aedeagus in lateral and in ventral view (without extruded internal sac); (29) apical median internal structure of the aedeagus. Scale bars: 27-28: 0.5 mm; 24-26, 29: 0.2 mm.