Ischnosoma involutum, 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 : 212-213

Ischnosoma involutum sp. n.

Figs 12 , 15 , 20–22 , 51 , 60 .

Description. Pronotum blackish-brown with lighter postero-lateral and posterior margins; elytra pale brown with blackish-brown area in the middle; head and abdomen blackish; posterior margins of tergites brownish-yellow; mouthparts, palpi, legs and basal two antennomeres yellow, antennomere III–XI blackish. Darker parts of pronotum, elytra, and tergites with weak blueish hue ( Fig. 15 ).

Head 0.59 mm broad; 0.65 times as broad as pronotum, broader than long, narrower posteriad, broadest in anterior half. Eyes very large and bulbous, longer than temples. Surface smooth without microsculpture. Antenna stout and long, antennomere X distinctly longer than broad.

Pronotum 0.91 mm broad; 0.75 mm long; 1.2 times as broad as long, broadest in the middle. Surface with very fine transverse microsculpture, finely and sparsely punctate.

Elytra distinctly widened posteriad; along suture 1.06 mm long; 1.33 times as broad as pronotum; 1.4 times as long as pronotum. Surface with very fine transverse microsculpture. Sutural row with 17 punctures, discal row with 17 punctures and lateral row with 18 punctures. Hind wings fully developed.

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

Length of forebody 2.47 mm; total body length 4.15 mm (up to abdominal segment VI).

Male. Sternite VII at posterior margin slightly concave, along central part of posterior margin with fine long setae ( Fig. 20 ). Sternite VIII with areas of palisade and beard-like setae forming three rows; with central acute seta; and with area of medial dense setae ( Fig. 21 ). Paramere and aedeagus: Fig. 22 .

Etymology. The specific epithet (Latin adjective: intricate, obscure) alludes to the extreme similarity of the habituswith some other species of this species group.

Type material. Holotype, male: " CHINA N Yunnan, Xue Shan nr. Zhongdian 3800 m 26.VI.1996 27°49N 99°34E C43 / collected by A. Smetana, J. Farkač and P. Kabátek" (cSch).

Distribution. Northwestern Yunnan ( Fig. 12 ): Xue Shan range.

Remarks. I. involutum sp. n. belongs to the species the I. pictum group, which is characterized by the following character combination: male eyes protuberant and bulbous; head widened anteriad; antenna long; antennomeres VIII to XI distinctly longer than wide; pronotum narrow, in posterior half with parallel lateral margins; elytra long and conspicuously widened posteriad, with numerous discal punctures. The new species differs from all the similar species by the shape and chaetotaxy of the male sternite VIII (with single pointed modified seta in the middle of the posterior margin between the clusters of beard-like and palisade setae.

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 20 – 22. Ischnosoma. involutum sp. n. Male sternite VII (20); male sternite VIII (21); aedeagus in ventral (left) and lateral view (22). Scale bar: 0.1 mm: a (Figs 20 – 21), b (Fig. 22).

FIGURES 46 – 53. Male sternite VIII with position of dark setae, beard-like palisade setae and median dense setae, schematic. Ischnosoma foedum sp. n. (46); I. noemi Kocian (47); I. splendidum (Gravenhorst) (48); I. maderi (Bernhauer) (49); I. duplicatum (Sharp) (50); I. involutum sp. n. (51); I. abstrusum sp. n. (52); I. yunnanum sp. n. (53). Scale bar: 0.1 mm.

FIGURES 58 – 60. Forebody. Ischnosoma yunnanum sp. n. (58); I. abstrusum sp. n. (59); I. involutum sp. n. (60). Scale bar: 1 mm.