Chaerilus pseudoconchiformus sp. n. and an updated key of the chaerilid scorpions from China (Scorpiones, Chaerilidae)

Abstract A new species, Chaerilus pseudoconchiformus sp. n., is described from Xizang, China. The present new species is distinguished from its congeners by a body length of 32−40 mm, carapace with the anterior margin straight, chela with length/width ratio average of 3.3 in males (3.2−3.4, two adults), and 2.5 in females (2.3−2.6, nine adults), eight or nine (eight usually) rows of denticles on fixed and movable fingers of pedipalp chelae, five pectinal teeth in males and three or four in females. To date, the chaerilid species fauna of China consists of nine species. An updated identification key to Chaerilus from China is presented.


Introduction
The small monotypic family, Chaerilidae, has been reported containing one genus with 39 species (1/2015, http://www.ntnu.no/ub/scorpion-files/). The only genus is Chaerilus, which is found in southern and southeast Asia. In Xizang (Tibet), the chaerilid scorpions live under stones and fallen trees in humid habitats.
Chaerilid scorpions have a unique type B trichobothrial arrangement (Vachon 1974;Soleglad and Fet 2001). Kovařík (2000) reported 18 species in this genus in his review. Kovařík (2012) published an identification key for the genus. Recently, new species were described (Kovařík et al. 2014;Lourenço and Pham 2014). Kovařík (2000) reported an old species and erected a new species of chaerilid from Xizang in his revision: C. pictus (Pocock, 1890) and C. tryznai Kovařík, 2000. In fact, one locality of C. tricostatus Pocock, 1899, Upper Rotung (Abor District), is also a territory belonging to Xizang (China). Therefore, Kovařík's revision recorded three species for China ). Zhu et al. (2004) recorded one chaerilid species (C. pictus) found in China. Qi et al. (2005) described one new species (C. tessellatus Qi, Zhu & Lourenço, 2005) and redescribed C. pictus (misidentification). Bastawade (2006) reported a new species from southeast Xizang: C. dibangvalleycus Bastawade, 2006. Zhu et al. (2008 redescribed C. tessellatus and C. tryznai, and pointed out that C. pictus as redescribed by Qi et al. (2005) was misidentified and erected it as a new species: C. conchiformus Zhu, Han & Lourenço, 2008. Zhu et al. (2008 also suggested that distribution of C. pictus in China was doubtful. Di and Zhu (2009) reported one new species: C. mainlingensis Di & Zhu, 2009 reviewed the genus Chaerilus in China, registered seven species, and described the female of C. tricostatus for the first time. Kovařík (2012) described a new species from Xizang: C. wrzecionkoi Kovařík, 2012. Di et al. (2014 reviewed the research history of the order Scorpiones from China, and recorded eight chaerilid species. To date, the chaerilid fauna of China consists of nine species including the new species described in this paper, C. pseudoconchiformus sp. n.

Material and methods
Illustrations and measurements were made using a Motic K700 stereomicroscope with an Abbe drawing tube and an ocular micrometer. The photos were taken with a Canon (650D) camera. Measurements follow Sissom (1990) and are given in mm. Trichobothrial notations follow Vachon (1974) and morphological terminology mostly follows Hjelle (1990 (Table 2); carapace with the anterior margin straight; chela with length/width ratio: average of 3.3 in males, and 2.5 in females (Table  2); eight or nine (usually eight) rows of denticles on fixed and movable fingers of pedipalp chelae; five pectinal teeth in males and three or four in females. Chaerilus pseudoconchiformus sp. n. can be distinguished from the geographically and morphologically closely related species (Tables 2−3, and key). Morphologically closest are C. conchiformus and C. wrzecionkoi. Both these species have similar body lengths, as well as similar numbers of denticle rows on fixed and movable fingers of the pedipalp chelae. They can be distinguished by the length/width ratio of the pedipalp chela: manus of pedipalp in male narrow and long, chela length/width ratio in male higher than 3 (average of 3.3 in two males, and 2.5 in nine females) in C. pseudoconchiformus sp. n.; manus of pedipalp in male robust (Kovařík 2012: Fig. 68), chela length/width ratio in both sex adults lower than 2.6 in C. wrzecionkoi (Kovařík, 2012: 2); manus of pedipalp in both sex adults robust (Zhu et al. (2008): Figs 3, 17), chela length/width ratio in one male adult is 2.4 (paratype: Ar.-MHU-XZ0102), in two females (including the holotype) lower than 2.0 in C. conchifor-  mus. Furthermore, C. pseudoconchiformus sp. n. has more slender pedipalps than C. wrzecionkoi (Table 1; Kovařík 2012: 13), in other words, the length ratio of pedipalp (LRP) is distinctly larger than the length ratio of total length (LRT) of C. pseudoconchiformus sp. n. and C. wrzecionkoi: 1.14 (LRP), 1.01 (LRT) in male holotypes; 1.08 (LRP), 0.95 (LRT) in female allotypes of C. pseudoconchiformus sp. n. and C. wrzecionkoi (Table 1). Etymology. The specific name refers to the geographically and morphologically most closely related species C. conchiformus, adding the Greek prefix "pseudo−" as "pseudoconchiformus", because the habitus of both sexes is very similar to that of C. conchiformus.
Description. Based on male holotype and female paratype. Coloration (Figs 1−4). Basically reddish brown. Carapace dark red-brown with black parts and yellowish stripes. Mesosomal tergites dark red-brown with yellowish stripes. Metasoma: all segments dark red-brown. Telson dark red-brown with reddish brown part; aculeus light red-brown. Chelicerae reddish brown with dark reticular pattern on dorsal surface. Pedipalps: femur, patella and chela dark red-brown with dark carinae. Legs dark red-brown and red-brown on distal segments. Sternum, genital operculum and sternites red-brown with some light parts. Pectines light yellow.
Morphology. Carapace carinated, with the anterior margin straight; with dense granules of nearly equal size; lateral furrow moderately deep; large granules form two longitudinal lateral carinae (Fig. 5). Median ocular tubercle with granules. Lateral ocular tubercle small with a pair of lateral eyes and some granules (Fig. 6). Lateral eyes distinctly smaller than median eyes (Fig. 5). Mesosoma: Tergites uniform distributing with granules of larger and unequal size; tergites I to II without carinae, each of tergites III to VI bearing a pairs of obsolete granular carinae on posterior margin, tergite VII bearing two pairs of obsolete granular lateral carinae, but middle pair is represented only by ridges without expressed carinae; sternum pentagonal; genital operculum triangular; pectinal teeth count 5/5 in males and 3−4 in females, with fulcra well developed (Figs 12−13); sternites III to VI are smooth, sternite VII granular without carinae (Fig. 11).
* 2 Nine rows of denticles on movable fingers of pedipalp chelae in the holotype (Kovařík 2012: Fig. 64), but the author described eight rows in C. wrzecionkoi (Kovařík 2012: 11). segments with sparse small granules. Vesicle is almost smooth; aculeus slightly curved (Figs 16−17). Chelicerae: Tibia surfaces smooth; thickly covered with numerous short, silky hairs, extending to ventral aspect of chelicerae and dorsal aspect of fixed fingers; ventral inner edges of movable finger with some minute teeth (2−3 obsolete teeth in two males and 3−9 well developed and obsolete teeth in nine females) (Figs 7−10).
Legs: Tibia without tibial spur. Basitarsus with two pedal spurs strongly developed. Tarsi with two rows of spiniform setae.
Variation. Coloration and morphology in holotype and paratypes are very similar (feature datasets please see Table 2).
Habitat. Found under the stones in mixed forest.

Distribution. China (Xizang).
Update key to species of the genus Chaerilus in China