Ischnosoma
Creators: name: Kocian, Matúš
name: Schülke, Michael
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Ischnosoma

description: Key to the Ischnosoma species of China and Taiwan
Ischnosoma mandschuricum, most likely a synonym of I. fusciventre and known only from the female holotype, is omitted in the key.
1 Anterior margin of pronotum without carina; exceptionally such a carina may be present only in lateral portions of anterior margin; best seen with opposite light reflection............................................................. 2
- Anterior margin of pronotum with carina along all its length.................................. pictum species group. 7
2 Ocular seta as long and thick as setae of pronotum (Fig. 56)................................ spelaeum species group. 3
- Ocular seta very short or missing................................................... I. convexum species group. 4
3 Larger, 3.1–3,6 mm (forebody 1.39–1.69 mm), elytra only with sutural, discal and lateral rows of punctures. Male sternite VII in the middle of posterior margin broadly and deeply concave, with median dent bearing some short setae (Fig. 5). Sternite VIII with posterior margin in the middle very deeply concave, with 6–7 rows of modified setae similar to opened zip (Fig. 6). Yunnan................................................................................ zipapertum sp. n.
- Smaller, 2.5–3.1 mm (forebody 1.11–1.28 mm), elytra with additional non-setiferous punctation. Male sternites VI and VII only with slight emargination at posterior margin, both with large triangular fields of dense setae (Zhu et al., 2005: figures 3–4). Shaanxi........................................................................ taibaiense Zhu et al.
4 Elytra besides sutural, lateral, and discal rows of punctures with fine punctation and pubescence on whole surface. Zhejiang..................................................................................... chinense (Bernhauer)
- Elytra besides sutural, lateral and discal row of punctures without additional punctation and pubescence................ 5
5 Pale fine pubescence in the middle of male sternite VIII not reaching posterior margin of sternite (Kocian 2003: figures 5, 9, 12). Base of inner structure of aedeagus at most with one oblong finger-shaped structure (Kocian 2003: figure 6). Body generally darker, pronotum and anterior part of tergites III–V brown. Widely distributed in China, East and Southeast Asia............................................................................................. convexum (Sharp)
- Pale fine pubescence in the middle of male sternite VIII reaching posterior margin of sternite. At least one pair of setae situated at the margin (Kocian 2003: figures 42, 46, 61, 180). Base of inner structure of aedeagus with group of finger-shaped structures (Kocian 2003: figures 58, 185). Body generally paler, pronotum (sometimes with darker spot in anterior part) and tergites III–V reddish-yellow................................................................................. 6
6 Dark setae at posterior margin and in the middle of male sternite VII not reaching margin (Kocian 2003: figure 179). Two pairs of dark setae in the middle of male sternite VIII (Kocian 2003: figure 180). Macropterous species. Thailand, Taiwan ................................................................................................. thubal Kocian
- Dark setae at posterior margin and in the middle of male sternite VII reaching margin (Kocian 2003: figure 45). Dark setae on male sternite VIII only in posterior and lateral parts of sternite (Kocian 2003: figure 46). Wing-dimorphic species, brachypterous or apterous specimens known only from Taiwan and Nepal. Widely distributed in South, East and Southeast Asia........................................................................ quadriguttatum quadriguttaum (Champion)
7 Elytra short, at suture shorter, as short as, or slightly longer than pronotum....................................... 8
- Elytra long, at suture distinctly longer (at least 1.1 times) than pronotum........................................ 16
8 Dorsal surface of head shiny, without microsculpture....................................................... 12
- Dorsal surface of head with conspicuous microsculpture...................................................... 9
9 Posterior margin of male sternite VII only slightly concave (Fig. 16). Sternite VIII: Fig 17, aedeagus: Fig. 18. Known from mountain ranges around Er Hai Lake in western Yunnan............................................ foedum sp. n.
- Posterior margin of male sternite VII deeply concave in the middle (Kocian 2003: figures 391, 400, 407).............. 10
10 Setae in last row of median area of male sternite VIII flattened and pointed. Male sternite VIII as in Fig. 43. Aedeagus: Kocian (2003: figure 408). Yunnan..................................................................... ruth Kocian
- Setae in last row of median area of male sternite VIII thin and fine, similar to other setae in this area. Male sternite VIII as in Figs 44 and 45. Aedeagus: Kocian (2003: figures 393, 396, 397, 402) .......................................... 11
11 Median area of dense setae of male sternite VIII larger (Fig. 44; Kocian (2003: figure 392)). Japan, central China, Thailand ............................................................. discoidale discoidale (Sharp) (brachypterous morph)
- Median area of dense setae of male sternite VIII smaller (Fig. 45; Kocian (2003: figure 401)). Taiwan ................................................................................................ discoidale taiwanum Kocian
12 Smaller species, 3.8–5.0 mm (forebody 2.0– 2.3 mm). Body uniformly reddish. Posterior angles of pronotum very well developed, angular. Male sternite VIII in posterior half with bald area, bordered by bow-like suture, and with median area of dense pointed and stouter setae (Kocian 2003: figure 440). Aedeagus: Kocian (2003: figures 441–442). Shaanxi and Yunnan.............................................................................................. absalom Kocian
- Larger species, 5.0–6.0 mm (forebody 2.3–3.0 mm. Body coloration different. Male sternite VIII and aedeagus different.. 13
13 Body paler, reddish-brown to brownish, head, central part of elytra and anterior parts of tergites often darker, blackish. Pronotum, elytra and abdomen with distinct bluish-golden hue. Pronotum narrower, posterior angles less marked. Apical margin of male sternite VIII broadly triangularly concave (Fig. 36), posterior half without bald area (Kocian 2003: figure 427). Aedeagus: Kocian (2003: figure 428). Widely distributed from Qinghai southwards to Yunnan................... evae Kocian
- Coloration different. Pronotum wider, posterior angles more distinct angular. Posterior half of male sternite VIII with distinct bald area.......................................................................................... 14
14 Pronotum pale reddish, posterior margin of elytra broadly pale. Posterior margin of male sternite VIII only with small triangulary emargination (Kocian 1997, Fig. 63). Aedeagus: Kocian (1997: figure 64). Northern and eastern Europe, Siberia, Mongolia, Russian Far East, in China only recorded from Heilongjiang.................................... bergrothi Hellén
- Head, pronotum and elytra unicolorous, dark brown to black. Posterior margin of male sternite VIII very deeply triangularly concave (Figs 10, 42)................................................................................ 15
15 Bald apical area of male sternite VIII bordered by thick modified setae anteriorly, laterally, and posteriorly (Fig. 42). Aedeagus: Kocian (2003: figure 455). Northern Yunnan................................................ farkaci Kocian
- Bald apical area of male sternite VIII bordered by thick modified setae only anteriorly and posteriorly (Fig. 10). Aedeagus as in Fig. 11. Yunnan. (Diancang Shan)........................................................... vicinum sp. n.
16 Elytra with two irregular discal rows of punctures (Kocian 2003: figure 316). Male sternites VII and VIII, and aedeagus: Kocian (2003: figures 308–312). Russian Far East, Japan, China, Thailand, Myanmar, Nepal and northern India ................................................................................................ duplicatum (Sharp)
- Elytra with one discal row of punctures.................................................................. 17
17 Discal row of elytra with less than 10 punctures........................................................... 18
- Discal row of elytra with more than 10 punctures.......................................................... 19
18 Smaller. Pronotum and elytra uniformly yellowish-red, elytra sometimes darker around scutellum. Head surface mostly with unconspicuous microsculpture. Male sternite VIII as in Fig. 48; aedeagus: Kocian (1997: figure 73). Holarctic species, in China known from Hebei, Qinghai, and Sichuan........................................ splendidum (Gravenhorst)
- Larger. Elytra dark with paler humeral spot and posterior margin. Head surface shiny, without microsculpture. Male sternite VIII as in Fig. 38, aedeagus: Kocian (2003: figure 421). Russian Far East, Japan, northern and central China .............................................................................................. fusciventre (Tichomirova)
19 Posterior half of male sternite VIII with distinct bald area.................................................... 20
- Posterior half of male sternite VIII without distinct bald area................................................. 21
20 Colorful species, head, pronotum and elytra black, only two transverse spots at the median part of margins of pronotum, humeral portions and posterior margins of elytra brightly yellowish. Anterior margin of bald area on male sternite VIII bordered with modified short and stout flattened (beard-like) setae (Fig. 34) and median area of dense pointed setae. Aedeagus as in Fig. 35. Yunnan........................................................................ gemellum sp. n.
- Less colorful species, head black, pronotum entirely pale reddish, sometimes with indistinctly darkened anterior part. Elytra pale brown, variable darkened in the middle. Anterior margin of bald area on male sternite VIII bordered only with modified short and thick flattened (beard-like) setae (Kocian 2003: figure 443). Aedeagus as in Kocian (2003: figure 444). Japan, China, northern Thailand ................................................................. bolitobioides (Bernhauer)
21 Head of male with large protuberant eyes (Figs 58, 60). Width of head across eyes dinstincly larger than across temples. Pronotum less transverse, smaller than elytra at shoulders. Species with distinct sexual dimorphism of eye size, shape of head, length of elytra and size of basal antennomeres.................................................................. 22
- Head of males with smaller, not protuberant eyes (Figs 57, 59). Width of head across eyes smaller than, or equal to width across temples. Pronotum more transverse. Species without distinct sexual dimorphism of eye size, shape of head, length of elytra and size of basal antennomeres................................................................... 26
22 Areas of palisade and beard-like setae of male sternite VIII larger, covering one third or more of median length of sternite (Fig. 24)............................................................................................... 23
- Areas of palisade and beard-like setae of male sternite VIII smaller, covering one quarter or less of median length of sternite (Fig. 21)........................................................................................... 25
23 Areas of palisade and beard-like setae of male sternite VIII larger, forming sixs rows, in the middle not separated from each other, bald median area small and closed (Fig. 24). Yunnan........................................ yunnanum sp. n.
- Areas of palisade and beard-like setae of male sternite VIII smaller, forming three to five rows, in the middle separated from each other, bald median area posteriorly opened........................................................... 24
24 Shape of median bald area behind median area of dense setae more rectangular (Fig. 47). Areas of palisade and beard-like setae of male sternite VIII larger, forming five rows. Area of median setae smaller, posterior rows of setae flattened and pointed (Kocian 2003: figure 355). Aedeagus as in Kocian (2003: figure 356). Yunnan..................... noemi Kocian
- Bald area behind median area of dense setae not distinctly rectangular (Fig. 49). Areas of palisade and beard-like setae of male sternite VIII smaller, forming three or four rows. Area of median setae larger and denser, median dense setae thin and not dis-
tinctly pointed (Kocian 2003: figure 330). Aedeagus as in Kocian (2003: figures 331, 336). Beijing, Sichuan, Yunnan............................................................................................ maderi (Bernhauer) 25 Middle of posterior margin of male sternite VIII between areas of palisade and beard-like setae connected by pointed modified seta. Bald area behind median area of dense setae larger, median setae sparser (Fig. 21). Yunnan.......... involutum sp. n.
- Middle of posterior margin of male sternite VIII between areas of palisade and beard-like setae without modified setae. Bald area behind median area of dense setae smaller, median setae denser (Kocian 2003: figure 324). Russian Far East, Japan, Northern China (Beijing, Gansu, northern Sichuan)............................................. rosti (Bernhauer)
26 Head surface mostly with distinct microsculpture. Elytra relatively short, at suture about 1.2 times longer than pronotum. Posterior margin of male sternite VII very broadly concave, bordered by very sparse long thin setae (Fig. 37; Kocian (2003: figure 435)). Aedeagus as in Kocian (2003: figures 437, 438). Gansu, Shaanxi, Fujian, Taiwan ................... bohaci Kocian
- Head surface shiny, without microsculpture............................................................... 27
27 Posterior margin of male sternite VII very broadly concave, bordered by very sparse long thin setae (as in Fig. 33) or denser thin setae (Kocian 2003: figure 344)..................................................................... 28
- Posterior margin of male sternite VII only in the middle broadly and deeply concave and bordered by dense very thin and long setae (as in Fig. 30).................................................................................. 29
28 Smaller species with shorter elytra (at suture about 1.2 times as long as pronotum). Coloration of head and pronotum uniformly pale. Posterior margin of sternite VIII bordered in median part by dense thin setae (Kocian 2003: figure 344). Aedeagus: Kocian (2003: figure 346). Yunnan, Myanmar ................................................ hieroboam Kocian
- Larger species with longer elytra (at suture more than 1.3 times as long as pronotum). Posterior margin of sternite VIII in the middle bordered by sparse thin setae (Kocian 2003: figure 410). Aedeagus as in Kocian (2003: figure 412). Northern India, Nepal, Yunnan................................................................... fasciatocolle (Champion)
29 Larger species with long elytra (at suture more than 1.2 times as long as pronotum). Colour darker, head, pronotum and elytra brown, with paler humeral spot. Bald median area between areas of palisade and beard-like setae of sternite VIII smaller (Figs 31, 52). Aedeagus: Fig. 32 ................................................................. abstrusum sp. n.
- Smaller species of variable elytral length (at suture 0.9–1.2 times as long as pronotum). Colour paler, pronotum and elytra yellowish-red, head and elytra in the middle often darker. Bald median area between areas of palisade and beard-like setae of male sternite VIII larger (Figs 44; Kocian 2003: figure 392). Aedeagus: Kocian (2003: figures 393, 396, 397). Japan, central China, Thailand ................................................... discoidale discoidale (Sharp) (macropterous morph)
description: Published as part of Kocian, Matúš & Schülke, Michael, 2016, New species and records of Ischnosoma Stephens (Coleoptera, Staphylinidae, Tachyporinae) from China, pp. 201-242 in Zootaxa 4105 (3) on pages 239-241, DOI: 10.11646/zootaxa.4105.3.1, http://zenodo.org/record/271275