Ischnosoma hirthei 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 : 506-507

Ischnosoma hirthei Kocian & Schülke , sp. n.

Figs 5 , 8 , 15–17 , 24 .

Description. Body yellowish-brown, head brown, elytra in anterior two thirds dark piceous, in posterior third and along suture reddish-brown. Antenna from antennomere 3 darker, brown ( Fig. 5 ).

Habitus as in Figs 5 , 8 . Head 0.41 mm wide; 0.61 times as wide as pronotum, as wide as long. Eyes little longer than temples. Ocular puncture very small with rudimentary, inconspicuous microscopic seta. Surface smooth without microsculpture. Antenna 1.08 mm long. Antennomere IX distinctly longer than wide, antennomere X slightly longer than wide.

Pronotum 0.68 mm wide, 0.58 mm long, 1.17 times as wide as long, widest in posterior fifth. Surface very shiny without microsculpture. Inner anterior and posterior punctures separated from pronotal margin by 2–3 times, outer anterior and posterior punctures by 1,5 times the diameter of punctures.

Elytra rectangular, parallel-sided, along suture 0.5 mm long, longer than wide (width combined); as wide as pronotum and 0.86 times as long as pronotum. Surface without microsculpture. Sutural and discal row with 3 punctures, lateral row with 3–4 punctures. Wings reduced.

Abdomen slightly tapering towards apex, sparsely punctate, with long pubescence. Tergite VII without palisade fringe. Surface smooth, without microsculpture.

Length of forebody 1.51 mm; total body length 3 mm.

Male. Sternite VII in the middle of posterior margin straight, not distinctly concave, chaetotaxy unmodified ( Fig. 15 ). Sternite VIII in the middle of posterior margin deeply concave, surface regularly pubescent, without distinctly modified setae ( Fig. 16 ). Internal sac of aedeagus in basal portion with two long apical sclerites and several smaller sclerites in basal portion ( Fig. 17 ).

Type material. Holotype, male: NEPAL: Pokhara , Südufer des Phewa Sees , Bachlauf, Gesiebe, 800–900 m, 8.V.2001, leg. G. Hirthe (cSch).

Etymology. The species is dedicated to Gunnar Hirthe (Güstrow), collector of the holotype.

Distribution. Central Nepal, Kaski district ( Fig. 24 ).

Remarks. I. hirthei sp. n. belongs to the I. convexum species group. It is characterized by small body size, reduced rows of punctures on the elytra, and differs from all similar species by the following character combination: only four pairs of dark long setae along apical margin of male sternite VII, these setae conspicuously distant from posterior margin; male sternite VIII with dark long setae only laterally, without dark setae in discal area, regularly lightly pubescent everywhere; base of internal sac of aedeagus with characteristic arrangement of sclerites.

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 15–17. Ischnosoma hirthei sp. n. Male sternite VII (15); male sternite VIII (16); aedeagus in ventral (left) and lateral view (17). Scale bars: 0.1 mm: a (Figs 15–16), b (Fig. 17).