Tetrabothrus cavus, Assing, 2015

Assing, Volker, 2015, On the Tetrabothrus fauna of China (Coleoptera: Staphylinidae: Aleocharinae: Lomechusini), Linzer biologische Beiträge 47 (1), pp. 127-143 : 130-133

Tetrabothrus cavus nov.sp. ( Figs 1-11 , Map 1 )

T y p e m a t e r i a l: Holotype Ƌ: " CHINA: Yunnan, Dali Bai Aut. Pref., Wuliang Shan , 20 km NW Weishan, 25°19'58''N, 100°07'59''E, 1900 m, creek valley, litter & old flood debris sifted, 17.IX.2009, leg. M. Schülke [CH09-58] / Holotypus Ƌ Tetrabothrus cavus sp. n., det. V. Assing 2015" (cAss). Paratypes: 1♀: same data as holotype (cSch); 1Ƌ: " CHINA: Yunnan, Wuding, Lion Mountain Scenic Area , 2200 m, 25°31'59''N, 102°22'36''E, stream valley with deciduous forest, moist litter sifted, 17.VIII.2014, leg. M. Schülke [CH14-11]" (cSch); 1♀: " CHINA: S-Shaanxi [CH12-02], Qinling Shan, 42 km SW Meixian, 34°01'32''N, 107°24'13''E, 1875 m, N-slope, secondary deciduous forest near creek, litter & grass sifted, 26.VII.2012, leg. M. Schülke " (cAss) .

E t y m o l o g y: The specific epithet (Latin, adjective: concave) alludes to the posteriorly excised female sternite VIII.

D e s c r i p t i o n: Species of variable body size; body length 4.8-6.2 mm; length of forebody 2.1-2.6 mm. Coloration: body reddish-brown to dark-brown, with the posterior margins of the abdominal segments indistinctly reddish; legs yellowish, with the apices of the femora broadly and distinctly infuscate; antennae reddish to dark-brown.

Head ( Fig. 1 ) approximately 1.2 times as broad as long; posterior angles completely obsolete; punctation extremely fine and sparse; median dorsal portion impunctate; pubescence whitish and suberect; microsculpture absent. Eyes large and bulging, but noticeably shorter than distance from posterior margin of eye to posterior constriction in dorsal view. Antenna 1.3-1.5 mm long and shaped as in Fig. 2 .

Pronotum ( Fig. 1 ) transverse, 1.06-1.08 times as broad as long and 1.16-1.19 times as broad as head, broadest in posterior half, narrowly margined; anteriorly strongly tapering, anterior angles not visible in dorsal view; lateral margins weakly convex in dorsal view; posterior angles rounded, but noticeable; punctation sparse and very fine; midline broadly impuncate; pubescence whitish and suberect; microsculpture absent.

Elytra ( Fig. 1 ) 0.88-0.96 times as long as pronotum; punctation and pubescence similar to those of pronotum; interstices without microsculpture. Hind wings present. Metatibia 0.85-1.10 mm long; metatarsus 0.64-0.70 times as long as metatibia; metatarsomere I approximately as long as the combined length of II and III.

Abdomen ( Fig. 3 ) narrower than elytra, broadest at tergites IV-V; tergites III-VI with very deep anterior impressions, the impression of tergite VI as deep as that of tergite V; tergites III-VII without microsculpture and impunctate except for few punctures bearing long dark setae at the posterior margins; tergite VIII ( Fig. 4 ) with thin and moderately long yellowish setae and with few interspersed longer and darker setae in posterior portion, posterior margin truncate or weakly convex; posterior margin of tergite VII with pronounced palisade fringe.

Ƌ: sternite VIII ( Fig. 5 ) transverse and with strongly convex posterior margin; median lobe of aedeagus 0.5 mm long and shaped as in Figs 9-11 ; paramere ( Fig. 6 ) 0.7 mm long and with slender and moderately long apical lobe.

♀: posterior margin of sternite VIII weakly to distinctly concave ( Figs 7-8 ).

C o m m e n t: The female from the type locality is distinctly smaller than the other type specimens. The female from Shaanxi differs from this specimen by the more distinctly concave posterior margin of sternite VIII ( Figs 7-8 ). However, no additional differences were found suggesting that they should represent different species. Males from Shaanxi would be needed to confirm the hypothesis that the female from the Qinling Shan is conspecific with the holotype.

C o m p a r a t i v e n o t e s: Tetrabothrus cavus is distinguished from the two species previously recorded from China by the different shape of the median lobe of the aedeagus and additionally as follows:

from T. puetzi (female unknown) by the different coloration of the legs ( T. puetzi : uniformly brown), the broader, more transverse pronotum, the deeper impressions on the abdominal tergites III-VI, and by the much longer parameres with longer and more slen- der apical lobes ( T. puetzi : parameres approximately 0.45 mm long);

from T. chinensis (female unknown) by the uniform coloration of the body ( T. chinensis : forebody dark-brown, abdomen reddish-brown), the coloration of the legs ( T. chinensis : legs brown with the femoral bases extensively yellow), the completely obsolete posterior angles of the head, the shorter and less massive antennae, the shape of the pronotum ( T. chinensis : anterior angles visible in dorsal view, and by the longer paramere. For illustrations of T. puetzi and T. chinensis see ASSING (2009), Figs 29-32 , and PACE (2012), respectively.

In external characters (habitus, coloration, anterior angles of pronotum not visible in dorsal view), T. cavus is most similar to T. nepalensis PACE, 1992 ( Nepal) , from which the new species differs by shorter antennae with less transverse antennomeres VII-X, the deeper anterior impressions of the abdominal tergites III-VI, and the smaller median lobe of the aedeagus with a smoothly curved ventral process ( T. nepalensis : median lobe 0.6 mm long and with abruptly curved ventral process). For illustrations of T. nepalensis see PACE (1992).

Tetrabothrus septentrionalis KISHIMOTO, 1997 is similar to T. cavus in that the anterior angles of the pronotum are not visible in dorsal view, but distinguished by the more slender and anteriorly more strongly tapering pronotum, the uniformly yellowish legs, the paler coloration of the pronotum and elytra, the indistinctly bicolored elytra, and the much narrower and apically more acute (lateral view) ventral process of the aedeagus. For drawings of the habitus and the sexual characters of T. septentrionalis see KISHIMOTO (1997) and MARUYAMA & KISHIMOTO (1999), respectively.

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 known distribution is confined to two localities in Yunnan and one in southern Shaanxi ( Map 1 ). The specimens were sifted from moist litter, flood debris, and grass in deciduous woodland at altitudes of 1875-2200 m.

Figures

Map 1: Distributions of Tetrabothrus species in China: T. puetzi (open triangle); T. inflexus (open circles); T. brevalatus (open star); T. cavus (filled circles); T. rubricollis (open diamond); T. chinensis (filled triangle).

Figs 1-8: Tetrabothrus cavus nov.sp. from Yunnan (1-7) and Shaanxi (8): forebody (1); antenna (2); abdomen (3); male tergite VIII (4); male sternite VIII (5); paramere (6); female sternite VIII (7- 8). Scale bars: 1, 3: 1.0 mm; 2, 4-5, 7-8: 0.5 mm; 6: 0.2 mm.

Figs 9-11: Tetrabothrus cavus nov.sp. from western (9) and eastern Yunnan (10-11): median lobe of aedeagus in lateral view (9-10); median lobe of aedeagus in ventral view (11). Scale bar: 0.2 mm.

Figs 29-32: Tetrabothrus chinensis PACE (holotype): forebody (29); head (30); antenna (31); abdomen (32). Scale bars: 29-30, 32: 1.0 mm; 31: 0.5 mm.