The genus Chaerilus Simon , 1877 ( Scorpiones , Chaerilidae ) in the Himalayas and description of a new species

A new species is described belonging to the genus Chaerilus Simon, 1877. Chaerilus annapurna sp. n. was discovered in the high plateaux of the Himalayas in Central-Western Nepal. For comparative purposes a precise re-diagnosis is proposed for Chaerilus truncatus Karsch, 1879, originally described from an imprecise locality in Himalaya. Th is species has recently been discussed by several authors: nevertheless, it has sometimes been the subject of misidentifi cation.


Introduction
Th e family Chaerilidae with its single genus Chaerilus remains among the least known taxa of extant scorpions.In the Catalog of Scorpions of the World (Fet 2000), 21 species have been listed in the genus Chaerilus Simon, 1877.In a very approximate revision of the genus, Kovařík (2000) defi ned 18 species as valid.He subsequently added two new species (Kovařík 2005).More recently, other new species from China, Indonesia, Laos, the Philippines and Vietnam have been described (Qi et al. 2005;Lourenço and Zhu, 2008;Lourenço and Ythier, 2008;Zhu et al. 2008;Lourenço 2009).A precise historical account of the group can be found in Lourenço and Zhu (2008).
Th e family Chaerilidae is distributed only in the Oriental Region, mainly in South and Southeast Asia.It was suggested (Lamoral 1980) that the ancestors of the chaerilids originated in Pangaean times as an eastern Laurasian relic that moved into the Oriental Region after the Indian plate become connected with Laurasia.Th e group became isolated in the Oriental Region as the Himalayas were raised up.
Although the type species of the genus, Chaerilus variegatus was described by Simon (1877) from Java, several species have subsequently been described from the Himalayas and nearby regions.Th e species from India, Nepal, Bangladesh and China, have proved to be extremely uniform in their morphology, and most were defi ned on the basis of weak diagnostic characters.Th e main reason for this comes from the fact that specimens are globally rare and poorly represented in collections.In several cases, species are represented by only one of the sexes or by juveniles of both sexes.Type material is frequently old and poorly preserved.Th is lead Kovařík (2000) to place several of the old Himalayan species in synonymy with Chaerilus truncatus Karsch, 1879, the fi rst to be described.Although the revision by Kovařík (2000) is rather poor, we concluded that these synonymies should be confi rmed with the aid of the available samples we had.It is quite possible that several old Himalayan species have been diagnosed on the basis of intra-specifi c variability.One exception is Chaerilus pictus (Pocock 1890) from Bangladesh which presents very marked sexual dimorphism in the shape of the telson.As a result, Chaerilus truncatus now appears to have a widespread distribution in the Himalayas.Even so, this rather 'common species', discussed by several authors, has also been the subject of subsequent misidentifi cations.In many cases, females have been identifi ed as males.Our conclusion is that males have never been clearly described.At present, a precise re-diagnosis is proposed for Chaerilus truncatus and a new associated species is described from Central Western Nepal.

Methods
Illustrations and measurements were made with the aid of a Wild M5 stereo-microscope with a drawing tube (camera lucida) and an ocular micrometer.Measurements follow Stahnke (1970) and are given in mm.Trichobothrial notations follow Vachon (1974) and morphological terminology mostly follows Hjelle (1990).

Taxonomic treatment
Chaerilidae Pocock, 1893 Chaerilus Simon, 1877 Chaerilus truncatus Karsch, 1879 Figs 1-11 Revised diagnosis.Scorpions of moderate to large size in relation to the other species of the genus, with a total length of 41 to 45 mm for males and 52 to 66 for females.General coloration reddish-yellow to reddish-brown with granulations and carinae somewhat more blackish on metasomal segments and pedipalps.Th is pattern of pigmentation proves to be invariably in preserved males, females and juveniles.
Anterior margin of carapace with a minute concavity in males; tegument smooth; straight and moderately granular in females; presence of two longitudinal carinae in both sexes; furrows moderately deep; two pairs of lateral eyes; one pair of small median eyes, about 1.5 times the size of lateral eyes; median eyes only slightly anterior to the centre of the carapace.Tergites smooth in males, intensely granulated in females; carinae obsolete.Sternum pentagonal, longer than wide; genital operculum plates with a sub-triangular shape.Pectinal tooth count 5-6 in males, 4-4 in females.Sternites smooth with spiracles small and oval-shaped; only VII weakly granulated in females.Metasoma: Carinae weakly granular in males, better marked in females; ventral carinae reduced or absent on segment I. Vesicle elongated with a pear-like shape in both sexes, smooth, with a short aculeus.Pedipalps slightly narrower in males; carinae well marked in both sexes; granulations more intensely marked in females.Fixed and movable fi ngers shorter than manus in both sexes with 9(10)-10(11) rows of granules on the dentate margins.Chelicerae characteristic of the family Chaerilidae (Vachon 1963).Trichobothriotaxy of type B; orthobothriotaxic (Vachon 1974); femur with 9 trichobothria, patella with 14, and chela with 14. Legs with pedal spurs moderately developed.Tarsi with two rows of spiniform setae.Hemispermatophore of Fusiform Type, with the distal lamina short and straight.
Material used for the diagnosis.India, Himalaya-Koollao, 1 female, MNHN-RS-0605; Himalaya-Dehra-Dun, 3 males, MNHN-RS-0606; W. Himalaya-Katta (Kalta) Pani, 1 male, MNHN-RS-0598; W. Diagnosis.Species of moderate size in relation to that of the other species in the genus, 49 to 55 mm in total length.General coloration reddish-yellow, marked intensely with variegated brownish spots.Th e exocuticular pigmentation becomes darker with age and fi nally turns blackish.Th is phenomen has already been observed in several other groups of scorpions (Lourenço and Cloudsley-Th ompson 1996).However, in the present case, it was also observed among juveniles.Th is would suggest that intermolt periods are rather long.Carapace moderately narrowed toward the anterior edge; better marked in females; acarinate and smooth in males; moderately granulated in females; anterior margin straight; furrows shallow in males, moderately deep in females.Metasomal carinae moderately marked in males; strongly marked in females; ventral carinae obsolete on segment I, weakly marked on segment II; latero-ventral and ventral carinae on segments IV-V composed of strong spinoid granules; other carinae with moderately marked spinoid granules.Telson with an elongated pear-like shape; dorsal surface strongly depressed in males, only slightly in females.Male pedipalps strongly elongated in comparison with female pedipalps; chela fi ngers strongly granulated in males, in particular on the ventral surface of movable fi nger; dentate margins of fi xed Figures 5-11.Chaerilus truncatus from India.5-6 Sternum, genital operculum and pectines, male and female 7-8 Metasomal segment V and telson, lateral aspect, male and female.9-11 Chaerilus anthracinus Pocock (= C. truncatus), male lectotype and female paralectotype.9-10 Metasomal segment and telson, lateral aspect, male and female 11 Cutting edge of movable fi nger with rows of granules, male (scales = 3 mm).Etymology.Th e specifi c name is placed in apposition to the generic name, and refers to the Annapurna Mountain, in the vicinity of which the new species was found, and seems to be endemic.
Description.Coloration: Basically reddish-brown, intensely marked with variegated brownish spots, before tegumental sclerifi cation (see diagnosis).Carapace reddishyellow.Tergites of the same colour as carapace; both with variegated spots.Metasomal segments yellowish to reddish-yellow; carinae reddish.Telson yellowish; tip of aculeus reddish.Chelicerae yellowish with diff used variegated spots; fi ngers and teeth reddish.Pedipalps reddish; chela fi ngers with the carinae dark to blackish; dentate margins of fi ngers almost blackish.Legs reddish-yellow with diff used brownish spots.Venter and sternites yellowish; pectines pale yellow.Once tegumental sclerifi cation has taken place general appearance is blackish and only pectines remain pale yellow.
Morphology: Carapace moderately narrowed anteriorly in males, more strongly marked in females; anterior margin straight, almost acarinate; smooth in males, moderately granulated in females; furrows shallow in males, moderately deep in females.Two  pairs of lateral eyes, and one pair of moderate median eyes, about 1.5 times the size of lateral eyes; median eyes anterior to the centre of the carapace.Tergites smooth in males with moderately marked granulations females; carinae obsolete in both sexes.Sternum pentagonal, longer than wide; genital operculum plates with sub-oval shape.Pectinal tooth count 5-5 in male holotype, 3-3 in female paratype.Sternites smooth with spiracles small and oval-shaped; carinae absent from VII. Metasoma: Segments I and II wider than long; segments III to V longer than wide.All the carinae moderately to strongly granular; ventral carinae obsolete on I, weakly marked on II; segments IV and V with latero-ventral and ventral carinae composed of strong spinoid granules.Vesicle very elongated with a pearlike shape, smooth; strongly dorsally depressed in males, only weakly depressed in females; aculeus moderately short.Pedipalps strongly elongated in males in comparison with females; femur with fi ve carinae; internal with spinoid granules.Patella with seven carinae; dorso-external weakly granular; dorso and basal-internal with spinoid granules.Chela with eight carinae, moderately to strongly granular; ventral median carinae moderate.Tegument moderately granular.Fixed and movable fi ngers longer than manus, strongly granular with 10-12(11-13) rows of granulations on the dentate margins.Chelicerae characteristic of the family Chaerilidae (Vachon 1963).Trichobothriotaxy of type B; orthobothriotaxic (Vachon 1974); femur with 9 trichobothria, patella with 14, and chela with 14. Legs with pedal spurs strongly developed.Tarsi with two rows of spiniform setae.Hemispermatophore of Fusiform Type, with the distal lamina short and curved on its distal portion.

Relationships
Chaerilus annapurna sp.n., shows morphological similarities with Chaerilus truncatus Karsch, 1879, also described from the Himalayas.Th e new species can, however, be readily distinguished by the following features: (i) the shape and structure of the telson, strongly depressed dorsally in males, (ii) male pedipalps much more elongated than female pedipalps (see Table I), (iii) movable fi nger of chela with very strongly marked granulation.

Conclusions
Although this study is only preliminary, some insights have been gained concerning the species of Chaerilus found in the Himalayas and nearby regions of India and Tibet.
Chaerilus truncatus is undoubtedly a rather common species, presenting intra-specifi c variations that led to the description of several 'closely associated' species.Consequently we agree with the decisions of previous authors (Kraepelin 1899;Kovařík 2000) who placed several of these species in synonymy of C. truncatus.
Chaerilus insignis Pocock, 1894, remains poorly characterized.Very few specimens are known and the type specimen, originally stored dry, is poorly preserved.Th e study of more material may show that this species is also conspecifi c with C. truncatus.

Table 1 .
Kovařík (2000)cribed and properly illustrated C. tryznai, without the study of the type of C. assamensis a fi nal decision cannot be taken in relation to these two species.Chaerilus pictus (Pocock, 1890) is one of the most peculiar species in the genus.Chaerilus gemmifer Pocock, 1894, is unquestionably a synonym of C. pictus, as already suggested on several museum labels (by Kraepelin and Simon; results not published) for the material deposited in Hamburg and Paris.Kovařík (2000)confi rmed this synonymy.Morphometric values (in mm) of Chaerilus truncatus, male and female from India and Chaerilus annapurna sp.n., male holotype and female paratype.