Ischnosoma bhojpur Kocian & Schülke, 2018

Kocian, Matúš & Schülke, Michael, 2018, New species and records of Ischnosoma Stephens (Coleoptera: Staphylinidae: Tachyporinae) from Nepal, Zootaxa 4442 (4), pp. 501-522 : 504-505

Ischnosoma bhojpur Kocian & Schülke , sp. n.

Figs 2–3 , 9 , 12–14 , 24 .

Description. Head and abdomen of holotype brown, pronotum and posterior margins of tergites reddish-brown, elytra dark-brown with paler humeral portions, scutellum and posterior margins; legs and palpi yellowish, antenna brownish-yellow ( Fig. 2 ). Paratypes have been subject to post-mortem darkening ( Fig. 3 ).

Habitus as in Figs 2–3 , 9 . Head 0.49–0.53 mm wide; 0.55–0.59 times as wide as pronotum, as wide as long. Eyes relatively small, slightly longer than temples. Ocular puncture very small, situated close to eye margin, with very short inconspicuous microscopic seta. Surface smooth without microsculpture, in some specimens with very fine irregular micropunctation. Antenna 1.11–1.26 mm long. Antennomeres IX–X slightly wider than long.

Pronotum 0.83–0.91 mm wide; 0.67–0.73 mm long; 1.23–1.28 times as wide as long, widest in posterior half. Surface without microsculpture, very finely and sparsely punctate. Inner anterior punctures separated from pronotal margin by three, outer anterior punctures by one, inner posterior punctures by three, and outer posterior punctures by three to four times the diameter of punctures.

Elytra quadrate, parallel-sided with sharply marked humeral angles, along suture 0.60–0.65 mm long; 1.0–1.05 times as wide as pronotum; 0.82–0.92 times as long as pronotum. Surface with very inconspicuous transverse microsculpture, with some very fine irregular punctures, and with very inconspicuous microscopic setae. Sutural row with 7–10 punctures, discal row with 6–10 punctures, and lateral row with 8–10 punctures. Wings reduced.

Abdomen tapering towards apex from segment IV, sparsely punctate. Tergite VII without palisade fringe. Surface smooth, without distinct microsculpture.

Length of forebody 1.84–1.89 mm; total body length 3.99–4.42 mm.

Male. Sternite VII in the middle of posterior margin without emargination, chaetotaxy unmodified ( Fig. 12 ). Sternite VIII in the middle of posterior margin broadly concave, apical portion without fine pubescence, but with modified dark setae; median portion with some conspicuously long thin setae ( Fig. 13 ). Internal sac of aedeagus in basal part with two groups of longer and shorter stiletto-like sclerites ( Fig. 14 ). Paramere with two long subapical setae.

Type material. Holotype, male: NEPAL: Bhojpur Distr. , E Salpa Pass, 3000– 2800 m, 24.V.1997, leg. W. Schawaller ( SMNS).

Paratypes (4): NEPAL, Panchthar Distr. , Oberlauf von Mai Majuwa Khola, Dhorpar Kharka, 2700 m, 27.– 28.VIII.1983, 257a Berlese, J. Martens & B. Daams leg., 2♂♂ (cKoc, cSch) ; NEPAL, Panchthar Distr. , Dhorpar Kharka, 2700 m, 13.–16.IV.1988, Martens & Schawaller, 324 mature Rhododendron-Lithocarpus forest, 1♂ 1♀ ( SMNS) .

Etymology. The specific name is a noun in apposition, derived from the name of the Nepalese district Bhojpur, where the holotype was collected.

Distribution. Eastern Nepal, districts Bhojpur and Panchthar ( Fig. 24 ).

Remarks. Ischnosoma bhojpur sp. n. belongs to the I. convexum species group. This species is closely related to I. thubal Kocian ( Thailand, Taiwan) and I. manasses Kocian , a species described from Thailand. These three species share a similar arrangement of dark thick setae on the male sternites VII and VIII (the latter with two pairs of dark setae in the middle). Ischnosoma bhojpur sp. n. differs from I. thubal by reduced wings and from both species, I. thubal and I. manasses , by a different arrangement of basal sclerites in the internal sac of aedeagus. Colouration and habitus are similar to both other species. Consequently a reliable identification is possible only based on the male sternites VII and VIII and the shape of the sclerites in the internal sac of the aedeagus. Paratypes have been subject to post-mortem darkening, probably a result of exposure to a chemical of unknown identity.

Figures

FIGURE 24. Distribution of Ischnosoma jumla sp. n. (red diamonds), Ischnosoma bhojpur sp. n. (green squares), Ischnosoma schmidti sp. n. (blue circle) and Ischnosoma hirtei sp. n. (yellow triangle).

FIGURES 2–7. Habitus of Ischnosoma bhojpur sp. n., Holotype (2); Paratype, darkened specimen (3); Ischnosoma jumla sp. n., Paratype (4); Ischnosoma hirtei sp. n., Holotype (5); Ischnosoma schmidti sp. n., Paratype (6); Ischnosoma fasciatocolle, partially darkened specimen (7). Scale bars: 1 mm.

FIGURES 8–11. Forebody. Ischnosoma hirthei sp. n. (8), I. bhojpur sp. n. (9), I. schmidti sp. n. (10), I. jumla sp. n. (11). Scale bar: 1 mm.

FIGURES 12–14. Ischnosoma bhojpur sp. n. Male sternite VII (12); male sternite VIII (13); aedeagus in ventral (left) and lateral view (14). Scale bars: 0.1 mm: a (Figs 12–13), b (Fig. 14).