Stilicoderus rastratus, Assing, 2013

Assing, V., 2013, Three new species and new records of Stilicoderus and Stiliderus (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 45 (2), pp. 1571-1585 : 1573-1575

Stilicoderus rastratus nov.sp.

( Figs 1-8 , Map 1 )

Type material: Holotype: " China: N-Sichuan [CH12-26], 70 km N Songpan, road S 301, above Gan lake , 33°15'26''N, 103°46'03''E, 2700 m, spruce forest with birch, litter, mushrooms, moss, and dead wood sifted, 12.VIII.2012, M. Schülke / Holotypus Stilicoderus rastratus sp.n. det. V. Assing 2013" ( cAss) . Paratype: " China [26]- N-Sichuan N Songpan, 33°15'26''N, 103°46'03''E, 2700 m, spruce forest with birch, 12.VIII.2012, V. Assing (cSch).

Etymology: The specific epithet is an adjective derived from the Latin noun rastrum (hoe, hatchet) and aludes to the shape of the ventral process of the aedeagus.

Description: Body length 5.8-6.3 mm; length of forebody 3.7-3.8 mm. Coloration: body blackish; legs with dark-brown femora, brown tibiae, and dark-reddish tarsi; antennae reddish.

Head ( Fig. 1 ) 1.10-1.15 times as long as broad and of oval shape; lateral margins behind eyes smoothly curving towards posterior constriction; posterior angles obsolete; punctation fine and sparse ( Fig. 2 ), only near posterior constriction with small area with larger and denser punctures; frons nearly impunctate; interstices distinctly broader than diameter of punctures, without distinct microsculpture. Eyes relatively small and weakly convex, approximately one third as long as postocular region from posterior margin of eye to posterior constriction. Antenna approximately 1.7 mm long; antennomeres II and IV weakly oblong, III approximately 1.5 times as long as broad, V and VI approximately as broad as long, and VII-X weakly transverse. Labrum with smooth, oblong median elevation, on either side of this elevation with microsculptured oval impression, anterior margin of labrum concave, middle of this concavity with a pair of tooth-like projections. Pronotum ( Fig. 1 ) approximately 1.1 times as long as broad and 0.9 times as broad as head; punctation fine and sparse, only posteriorly (near posterior margin and on either side of impunctate midline) denser and coarser; midline broadly impunctate; interstices glossy.

Elytra ( Figs 1, 3 ) approximately as long as pronotum; humeral angles marked; suture somewhat elevated; punctation moderately dense, distinctly coarser than that of head and pronotum; interstices without distinct microsculpture. Hind wings probably present. Metatarsomere I approximately as long as combined length of II and III.

Abdomen approximately as broad as elytra; punctation fine and moderately dense; interstices with shallow microsculpture; posterior margin of tergite VII with palisade fringe.

: sternite VII strongly transverse, approximately twice as wide as long, near posterior margin with few modified short and shout setae ( Fig. 4 ); sternite VIII ( Fig. 5 ) moderately transverse, posterior excision deep and V-shaped, nearly reaching middle of sternite; aedeagus ( Figs 6-8 ) 0.9 mm long; ventral process slender, straight, and somewhat hatchet-shaped apically.

Comparative notes: Based on the external and the male sexual characters, S. rastratus undoubtedly belongs to the S. japonicus group, which previously included two species, the widespread S. japonicus SHIBATA 1968 and S. formosanus ROUGEMONT 1996 ( Taiwan; China: Fujian). It is readily distinguished from the sympatric S. japonicus by distinctly smaller size, shorter and less slender antennae ( S. japonicus : antennomeres II and IV nearly twice as long as broad; preapical antennomeres not distinctly transverse), the relatively larger eyes ( S. japonicus : approximately one fourth as long as postocular region), the much sparser punctation of the head, the less oblong pronotum, the distinctly finer and sparser punctation of the pronotum ( S. japonicus : punctation dense, rather coarse, and somewhat granulose), the broader impunctate band on the pronotum, and by the male sexual characters (posterior excision of sternite VIII much smaller; aedeagus smaller and with ventral process of different shape). For illustrations of the male sexual characters of S. japonicus see ROUGEMONT (1986a). The new species differs from S. formosanus by the more slender body, different head shape ( S. formosanus : head nearly subquadrate), the sparser and finer punctation of the head ( S. formosanus : posterior portion of head extensively with dense and rather coarse punctation), the more slender pronotum with much finer and sparser punctation ( S. formosanus : punctation on either side of the impunctate midline dense and granulose), and the male sexual characters (posterior excision of sternite VIII of different shape; aedeagus smaller and with ventral process of different shape). For illustrations of the male sexual characters of S. formosanus see ROUGEMONT (1996).

Distribution and natural history: Thetypelocalityissituatedto the north of Songpan in northern Sichuan ( Map 1 ). The specimens were sifted from leaf litter in a mixed forest with dominant spruce and scattered birch at an altitude of 2700 m.

Figures

Map 1: Distributions of Stilicoderus japonicus (black circles: examined records; white circles: literature records) and S. rastratus (star).

Figs 1-8: Stilicoderus rastratus: (1) forebody; (2) median portion of head; (3) sutural portion of elytra; (4) posterior margin of male sternite VII; (5) male sternite VIII; (6-7) aedeagus in lateral and in ventral view; (8) apex of ventral process. Scale bars: 1: 1.0 mm; 2-3, 5-7: 0.2 mm; 4, 8: 0.1 mm.