Genus Charmus Karsch, 1879

(Figs. 12, 41–43, 47–119, 194, 423–426, 548, Tables 1– 2)

Charmus Karsch, 1879: 104; Kraepelin, 1899: 39; Pocock, 1900: 31–32; Kraepelin, 1913: 131; Vachon, 1982: 79, 81; Tikader & Bastawade, 1983: 140–152, figs. 382–416; Sissom, 1990: 101; Kovařík, 1998: 120; Lourenço, 2000: 295; Kovařík, Soleglad & Fet, 2007: 201; Kovařík, 2009: 31.

= Heterocharmus Pocock, 1892: 46–47,

type species by monotypy Heterocharmus cinctipes Pocock, 1892 (= Charmus laneus Karsch, 1879) (syn. by Kraepelin, 1899: 39; Pocock, 1900: 31).

TYPE SPECIES. Charmus laneus Karsch, 1879

DIAGNOSIS. Small buthids, adults 12 mm (male) – 23.5 mm (female). Sternum type 1, subpentagonal, roughly as wide as long, exhibiting horizontal compression. Pedipalps trichobothrial pattern Aα; femur trichobothrium d 2 located dorsally, patella d 3 dorsal of dorsomedian carina; chela with 3 Eb trichobothria on manus. Movable finger of pedipalp longer than manus. Pectines with or without fulcra. Dentate margin of pedipalp chela movable finger with distinct granules divided into 8–9 linear rows, apical rows of 4–6 granules, and 3 terminal granules. Cheliceral fixed finger armed with two denticles on ventral surface (Fig. 67a). Tergites I –VI granular, with one clearly visible carina. Carapace granular without carinae, anterior edge with epistome present medially. Metasomal segments IV–V punctate without developed carinae. Telson vesicle punctate, without subaculear tooth. Pedipalps, metasoma and telson densely hirsute. Legs III and IV with well developed long tibial spurs, first and second tarsomeres with ventral setae.

NOTE. A remarkable feature of the metasoma and telson of Charmus laneus is the extremely dense pubescence (Figs. 71–73). All segments bear an abundance of fine setae of various lengths emerging from pits containing sockets or perforations in the thickened cuticle. These setae can be divided into at least two types: (1) straight or uniformly curved, non-fluorescent golden setae; and (2) terminally curved, brightly fluorescent, translucent setae with intense pinpoint fluorescence at the tip (Figs. 6 8–70). Comparing these setae to similar kinds of setae found in other scorpions, we suggest that type 1 setae may be mechanoreceptive and tactile, and type 2 setae may be chemoreceptive in function. Putative chemotactic microsetae in other scorpions are typically also fluorescent and exhibit a similar, apically curved shape, but are usually quite short compared to the long fluorescent setae seen here. A similar densely hirsute metasoma is also present in C. saradieli sp. n. and was also described in the other two known members of the genus, C. indicus Hirst, 1 915 and C. singhagadensis Tikader et Bastawade, 1983 (Sreenivasa Reddy, 1966: 247–256; Tikader & Bastawade, 1983: 140–152). A similar, probably homologous development of dense setation is also observed in the closely related genus Thaicharmus (Kovařík, 1995, 2013; Mirza et. al., 2016). This massive concentration of multimodal sensory input indicates that Charmus is another example of the evolution of the metasoma into a specialized sensory organ. As noted previously, this has apparently occurred independently in several different buthid lineages, e.g. Butheoloides Hirst, 1925; Isometroides Keyserling, 1885; Karasbergia Hewitt, 1914; Microbuthus Kraepelin, 1898; Orthochirus Karsch, 1892; etc. (E. Fet et al., 2003; Lourenço, 2001, 2003; Lowe, 2010; Prendini, 2004).

DISTRIBUTION. India, Sri Lanka.