Genus Tyrus Aubé, 1833 (Figs 1–6) Tyrus Aubé, 1833: 15. Type species: Pselaphus mucronatus Panzer, 1803 (by monotypy). (list of synonyms see Hlaváč & Chandler 2005: 116) Diagnosis. Head with frontal and vertexal foveae; maxillary palpomeres II–IV basally pedunculate; pronotum with antebasal sulcus connecting median and lateral antebasal foveae; abdomen with tergite IV as long as to slightly longer than tergite V. Redescription. Length 1.5–2.7 mm (minimal size taken from Blattný 1925: 217; Bryant 1915: 299). Habitus as in Fig. 1. Head (Fig. 2 A) with short frontal rostrum, antennal tubercles moderately prominent and close; with setose frontal and vertexal foveae; with eleven antennomeres, clubs formed by apical three antennomeres; lacking postantennal notches at lateral margins; with indistinct lateral postantennal pits (Fig. 2 B); ocular-mandibular carinae present; ocular canthi variably present; maxillary palpi (Figs 4 D, 5D) with palpomeres II lengthily pedunculate, III and IV briefly pedunculate at bases, III triangular, IV elongately oval to fusiform, apices broadly rounded, with distinct palpal cone; gula (Fig. 2 C) flat, lacking median carina or sulcus, foveae close in transverse opening. Pronotum (Fig. 2 D) with transverse antebasal sulcus connecting median and lateral antebasal foveae; lateral procoxal foveae present (Fig. 2 E). Each elytron (Fig. 2 F) with two basal foveae; with subbasal fovea; sutural stria entire; discal stria exceeding elytral midpoint; apicolateral clefts present. Thorax (Fig. 3 A) with median mesoventral foveae in shared opening, lateral mesoventral foveae forked; lateral mesocoxal foveae and mesofurcal foveae present; with median metaventral fovea, posterior margin of metathorax medially emarginate. Legs with third tarsomeres longer than second tarsomeres; claws subequal in length. Abdomen (Figs 3 B–D) with tergite IV as long as to slightly longer than tergite V; tergite IV with shallow basal sulcus, large mediobasal foveae moving laterally approaching small anterior and posterior basolateral foveae on each side, median discal carina usually present; tergites V–VIII each with one pair of basolateral foveae; sternite IV with shallow basal sulcus; sternites IV–VII each with pair of basolateral foveae. Sexual dimorphism usually not obvious. Males of Asian species with the scape lightly modified and the mesotibiae apically protuberant. Distribution. Seven species are known from the Oriental region, three species and one subspecies from the Palearctic region, three species from the Nearctic region, and one extinct species described from Baltic amber (Hlaváč & Chandler 2005: 117). Biology. Biological information for Tyrus species, if known, is generally limited to statements on the habitats in which the adults have been collected. For the Nearctic species, T. corticinus (Casey) was found under bark of pines and Douglas fir, under bark of Betula occidentalis, and with ant Formica sanguinea (Casey 1887; Chandler 1997, 2003; Schwarz 1895), and T. humeralis (Aubé) was found under bark of pine, spruce and balsam fir, also from tree holes, in rotten pine log, at UV light, and with ants Aphaenogaster tennesseensis and Camponotus pennsylvanicus (Chandler 1997; Schwarz 1890; Eldredge pers. comm.). In the Palaearctic region, T. japonicus Sharp was collected under bark of large fallen trees, rotten woods and by flight intercept trap in the deciduous forest (Nomura pers. comm.), T. mucronatus mucronatus (Panzer) was found under bark of dead trees, in moss, and with ant Formica fuliginosa (Besuchet 1974; Casey 1887; Fleischer 1888; Jeannel 1950; Schatzmayr 1904), and T. peyroni Saulcy was taken under a stone (Saulcy 1874). The Oriental T. corticalis (Raffray) was collected from under tree bark (Raffray 1890), T. myrmecophilus Bryant was found under bark with ants (Bryant 1915, without statement of species or genus), Tyrus sinensis, and T. sichuanicus described below were taken from ant colonies of Formica spp. nesting under rock or fallen tree, and T. yajiangensis was possibly taken from sifted leaf litter or under tree bark. Comparative notes. Tyrus is allied to the largely Oriental Tyrodes Raffray, and New Zealand and Australian Hamotulus Schaufuss based on the basally pedunculate, elongate maxillary palpomeres II–IV, and the pronotum with an antebasal sulcus that connects the median and lateral antebasal foveae. Tyrodes is generally smaller, has small, nude, easily overlooked frontal fovea (Hlaváč & Chandler 2005: 93) while Tyrus has greater size, and distinct and setose frontal fovea. Hamotulus has a pair of tubercles between the vertexal and frontal foveae on the head (absent in one species), and a deep sulcus at the base of tergite IV (Chandler 2001: 433), while Tyrus lacks these tubercles, and the basal sulcus of tergite IV is shallow. Tyrus sichuanicus Yin and Nomura, new species (Fig. 1 A, 4) Type material (6 33, 23 ♀♀). Holotype: CHINA: 3, labeled ‘ CHINA: Sichuan, Ya’an County / Shimian, Liziping N. R., Chaheba / roadside, 28°57ʹ21″N / 102°15ʹ0 1″E, alt. 2615 m, colony / of Formica sp., under rock / 16.vii.2012, Dazi, Peng & Yin leg. [1 ex. Formica sp. pinned under holotype]’ (SNUC). Paratypes: CHINA: 1 3, 10 ♀♀, same label data as holotype; 2 33, 11 ♀♀, same label data, except ’ 02.viii.2012, Zhong Peng leg.’ (SNUC); 1 3, labeled ‘Mt., Jiudingshan (3,200 m) / Chapingshan Mts. / Mao Xian, Sichuan Prov. // (SE-China) [should be SW-China!] / 22.ix.1996, S. Nomura leg. [1 ex. Formica sp. pinned under the paratype]’ (NSMT); 1 ♀, labeled ‘ China: Sichuan Prov. / Yakou (Meigu to Yuexi) / 28°39ʹN, 102°59ʹ E / 2550 m, 14-VI-2012 / Ye LIU leg. [2 ex. Formica sp. pinned under the paratype]’ (SNUC); 1 3, labeled ‘ CHINA: W-Sichuan (15) / Daxue Shan, Hailuogou Glacier / Park, Camp 2, 2550– 2700 m / 29°35ʹ16″N, 102°01ʹ53″E / 30./ 31.05.1997, M. Schülke’ (pcMS); 1 ♀, labeled ‘ China, Sichuan Prov., / Liziping env., near / Shimian, 200 km SW / of Ya’an, 27.vi–3.vii / 1991, Z. Kejval lgt’ (pcPH). Diagnosis. Antennomeres IX–X each subcylindrical; ocular canthi present; maxillary palpomeres IV nearly fusiform; mesotrochanters with two long spines; mesotibiae with long apical spur. Description. Male (Fig. 1 A). Length 2.29–2.70 mm. Head about as long as wide, HL 0.47–0.55 mm, HW 0.45–0.49 mm; eyes each composed of about 40–50 facets. Antennae (Fig. 4 A) elongate, scapes laterally expanded (Fig. 4 C), clubs as in Fig. 4 B. Maxillary palpi (Fig. 4 D) with palpomeres I short, II lengthily pedunculate, III nearly triangular, IV fusiform. Pronotum slightly longer than wide, PL 0.50–0.57 mm, PW 0.47–0.51 mm, with lateral margins nearly straight. Elytra wider than long, EL 0.61–0.68 mm, EW 0.90–1.01 mm. Protrochanters with triangular ventral spine, profemora with two blunt spines on ventral margin (Fig. 4 E); mesotrochanters (Fig. 4 F) with two large ventral spines; mesotibiae (Fig. 4 G) slightly arched, with long apical spur (Fig. 4 H). Abdomen broad at base and narrowed apically, AL 0.71–0.90 mm, AW 0.92–1.04 mm. Sternite IX as in Fig. 4 I. Aedeagus length 0.48–0.51 mm, with asymmetric median lobe (Figs 4 J–L). Female. Similar to male in general; BL 2.31–2.62 mm, HL 0.50–0.51 mm, HW 0.45–0.48 mm, PL 0.51–0.58 mm, PW 0.48–0.56 mm, EL 0.56–0.70 mm, EW 0.93–1.07 mm, AL 0.74–0.83 mm, AW 0.94–1.07 mm. Eyes each composed of about 40 facets. Scape simple; mesotibiae lacking apical spur; tergite VIII (Fig. 4 M) and sternite VIII (Fig. 4 N) transverse; genital complex as in Fig. 4 O. Distribution. Southwest China: Sichuan. Host ant. Formica sp. Biology. All adults were collected from ant nests during an investigation of myrmecophilous pselaphine in Liziping Natrual Reserve (Figs 7 A–C). More than one-hundred ant nests were explored, and 203 pselaphines placed in 11 species were collected. The environment was dominated by two ant species, Formica sp. and Myrmica sp. Both species build their nests under different sizes of rocks. Unfortunately the two ant species were confused at the collection site. The association of the new species with Formica sp. was confirmed based on the paratypes from Jiudingshan and from the Pass between Meigu and Yuexi (see collection data above). Etymology. The new species is named after the province where all individuals of the new species were found. Tyrus sinensis Raffray (Fig. 1 B, 5) Tyrus sinensis Raffray, 1912: 442. Type locality: Yunnan, Southwest China. Material examined (1 3). CHINA: 3, labeled ‘ CHINA: Xizang, Mangkang Count. / Hongla Shan Mt., 29°12ʹ12ʹʹN / 98°39ʹ40ʹʹE, ca. 3700 m, colony / of Formica sp. under dead wood / 25.vii.2011, Wen-Xuan Bi leg. [1 ex. Formica sp. pinned under the paratype]’ (SNUC). Diagnosis. Antennomeres IX obconical, X nearly trapezoidal, slightly transverse; ocular canthi absent; maxillary palpomeres IV nearly oval; mesotrochanters with two long spines; mesotibiae with short apical spur. Redescription. Male (Fig. 1 B). Length 2.60 mm. Head about as long as wide, HL 0.40 mm, HW 0.41 mm; eyes each composed of about 45 facets. Antennae (Fig. 5 A) elongate, scapes slightly expanded laterally (Fig. 5 C), clubs as in Fig. 5 B. Maxillary palpi (Fig. 5 D) with palpomeres I short, II lengthily pedunculate, III nearly triangular, IV oval. Pronotum about as long as wide, PL 0.52 mm, PW 0.51 mm, with lateral margins nearly straight. Elytra wider than long, EL 0.68 mm, EW 1.02 mm. Protrochanters with short triangular ventral spine, profemora with two blunt spines on ventral margin (Fig. 5 E); mesotrochanters (Fig. 5 F) with two large ventral spines; mesotibiae (Fig. 5 G) strongly arched, with short apical spur (Fig. 5 H). Abdomen broad at base and narrowed apically, AL 1.00 mm, AW 1.08 mm. Sternite IX as in Fig. 5 I. Aedeagus length 0.51 mm, with asymmetric median lobe (Figs 5 J–L). Female. Not examined. Similar to male in general; BL 2.40 mm (Raffray 1912: 443). Distribution. Southwest China: Yunnan, Xizang (= Tibet, new provincial record). Host ant. Formica sp. Biology. The single male was collected from a colony of Formica sp. nesting on the ground under a dead tree (Bi per. comm.) (Fig. 7 D). Comments. The type material of T. sinensis (a female) was not examined, but the form of the antennomeres, the simple postgenae, and the nearly oval maxillary palpomeres IV of the single male from the Hongla-Shan Mountain highly agree with the descriptive details provided by Raffray (1912: 443), in combination with the fact that the collection site of this male is near the border of Xizang and Yunnan, it is therefore identified as T. sinensis. Tyrus yajiangensis Yin and Li, new species (Fig. 6) Type material (1 3). Holotype: CHINA: 3, labeled ‘ CHINA: W-Sichuan 1999 / Ganzi, Tibet. Aut. Pref., Yajiang Co. / Shalui Shan, Bachtal 6 km WSW / Yajiang, 3250 m, 30°01ʹN / 100°57ʹE, Laubstreu, Rinde, Pilze / 4.VII., leg. M. Schülke’ (pcMS). Diagnosis. Antennomeres IX–X each elongate, narrowed apically; ocular canthi present; maxillary palpomeres IV nearly oval; mesotrochanters with two long spines; mesotibiae with short apical spur. Description. Male. Length 2.48 mm. Head about as long as wide, HL 0.52 mm, HW 0.50 mm; eyes each composed of about 45 facets. Antennae (Fig. 6 A) elongate, scapes expanded laterally (Fig. 6 C), clubs as in Fig. 6 B. Maxillary palpi (Fig. 6 D) with palpomeres I short, II lengthily pedunculate, III nearly triangular, IV nearly oval. Pronotum about as long as wide, PL 0.52 mm, PW 0.54 mm, with lateral margins nearly straight. Elytra wider than long, EL 0.68 mm, EW 1.07 mm. Protrochanters triangularly projecting ventrally, profemora with two blunt spines on ventral margin (Fig. 6 E); mesotrochanters (Fig. 6 F) with two large ventral spines; mesotibiae (Fig. 6 G) slightly arched, with short apical spur (Fig. 6 H). Abdomen broad at base and narrowed apically, AL 0.76 mm, AW 1.00 mm. Sternite IX as in Fig. 6 I. Aedeagus length 0.45 mm, with asymmetric median lobe (Figs 6 J–L). Female. Unknown. Distribution. Southwest China: Sichuan. Biology. The adult was possibly taken from sifted leaf litter or under tree bark. Etymology. The new species is named after the type locality.

Published as part of Yin, Zi-Wei, Nomura, Shûhei & Li, Li-Zhen, 2013, Redescription of Tyrus Aubé and T. sinensi s Raffray (Coleoptera: Staphylinidae: Pselaphinae), and two new species from Sichuan, Southwest China, pp. 47-57 in Zootaxa 3637 (1) on pages 48-54, DOI: 10.11646/zootaxa.3637.1.5, http://zenodo.org/record/283594