Ischnosoma gemellum, Kocian, Matúš & Schülke, Michael, 2016

Kocian, Matúš & Schülke, Michael, 2016, New species and records of Ischnosoma Stephens (Coleoptera, Staphylinidae, Tachyporinae) from China, Zootaxa 4105 (3), pp. 201-242 : 216-219

Ischnosoma gemellum sp. n.

Figs 12 , 14 , 33–35 , 40 , 57 .

Description. Body ( Fig. 14 ) distinctly two-colored, blackish and redish-yellow. Pronotum in posterior part laterally with reddish-yellow spot. Humeral spot, posterior margin of elytra, posterior margins of tergites, legs, palpi and first two antonnomers reddish-yellow. Elytra and abdomen with slight bluish hue.

Head 0.55–0.56 mm broad; 0.57–0.59 times as broad as pronotum, as broad as long. Eyes big, distinctly longer than temples. Surface with distinct sparse microsculpture composed of transverse and obligue waves. Antenna thin, 1.51–1.61 mm long. Antennomere X slightly longer than broad.

Pronotum 0.96 mm broad; 0.82–0.88 mm long; 1.08–1.16 times as broad as long, broadest behind middle. Surface with very fine transverse microsculpture, finely and sparsely punctate.

Elytra slightly widened posteriad; along suture 1.03–1.06 mm long; 1.23–1.26 times as broad as pronotum; 1.2–1.26 times as long as pronotum. Surface with very fine transverse microsculpture. Sutural row with 12–18 punctures, discal row with 12–16 punctures and lateral row with 15–17 punctures. Wings fully developed.

Abdomen gradually tapering towards apex, sparsely puntate. Tergite VII with palisade fringe. Surface smooth with very fine transverse microsculpture.

Length of forebody 2.47–2.73 mm; total body length 4.5–5.1 mm.

Male. Sternite VII in the middle of posterior margin broadly concave, with sparse thin setae ( Fig. 33 ). Sternite VIII near posterior margin with area without pubescence, bordered by suture. Non-pubescent area at posterior margin enframed by beard-like setae forming two rows. Anterior to non-pubescent area with median cluster of short, dense, and pointed setae ( Fig. 34 ). Paramere and aedeagus: Fig. 35 .

Etymology. The specific epithet (Latin, adjective: twin-born) alludes to the similarity of this species with I. bolitobioides .

Type material. Holotype, male: " CHINA: Yunnan ( CH 07-14A), Baoshan, Pref. Gaoligong Shan, 33 km SE Tengchong, 2100–2200 m, 24°51'22''N, 98°45'36''E, decid forest, litter, wood, fungi sifted, 4.VI.2007, M.Schülke / Sammlung M. Schülke, Berlin" (cSch).

Paratypes (2): " CHINA: N-Yunnan (C 2005-07 A), Diqing Tibet Aut. Pref., Deqin Co., Meili Xue Shan, E-side, 12 km SW Deqin, 2890 m, 28°25'30''N, 98°48'47''E / small creek valley, mixed forest with bamboo, leaf litter, moss, dead wood, sifted, 13.6.2005, leg. M.Schülke (C 2005-07 A) / Sammlung M. Schülke, Berlin", 1 ex. (cSme); " CHINA, Sichuan, Gongga Shan, Lake abv. Camp 2, 2750 m, 25.VII.1994, A. Smetana (C23)", 1 ex. (cKoc).

Distribution. Western Yunnan (Gaoligong Shan, Meili Xue Shan) and Western Sichuan (Gongga Shan) ( Fig. 12 ).

Remarks. I. gemellum sp. n. is very closely related to I. bolitobioides , from which it differs by the chaetotaxy of the male sternite VIII (median cluster of modified setae larger and formed by two types of setae: broadly flattened setae bordering anterior margin of median non-pubescent area and short pointed setae anterior to these flattened setae. In I. bolitobioides , there are only broadly flattened setae arranged in some irregular rows anterior to non-pubescent area.

Figures

FIGURE 12. Distribution of Ischnosoma vicinum sp. n. (square), Ischnosoma involutum sp. n. (triangle) and Ischnosoma gemellum sp. n. (circles) in China.

FIGURES 13 – 15. Habitus of Ischnosoma foedum sp. n. (13); Ischnosoma gemellum sp. n. (14); Ischnosoma involutum sp. n. (15).

FIGURES 33 – 35. Ischnosoma gemellum sp. n. Male sternite VII (33); male sternite VIII (34); aedeagus in ventral (left) and lateral view (35). Scale bars: 0.1 mm: a (Figs 33 – 34), b (Fig. 35).

FIGURES 36 – 45. Male sternite VIII with position of dark setae, beard-like palisade setae and median dense setae, schematic. Ischnosoma evae Kocian (36); I. bohaci Kocian (37); I. fusciventre (Tikhomirova) (38); I. bolitobioides (Bernhauer) (39); I. gemellum sp. n. (40); I. absalom Kocian (41); I. farkaci Kocian (42); I. ruth Kocian (43); I. discoidale discoidale (Sharp) (44); I. discoidale taiwanum Kocian (45). Scale bar: 0.1 mm.

FIGURES 54 – 57. Forebody. Ischnosoma vicinum sp. n. (54); I. foedum sp. n. (55); I. zipapertum sp. n. (56); I. gemellum sp. n. (57). Scale bar: 1 mm.