Genus Reddyanus Vachon, 1972 stat. n.

(Figs. 14, 199, 201–220, 225–236, 245–250, 254–402, 409–420, 551–554, 561–570, Tables 3–5)

Isometrus (Reddyanus): Vachon, 1972: 176–177, figs. 14, 16, 18, 20; Vachon, 1982: 90–101, 108–110, figs. 47–67, 88–91; Fet & Lowe, 2000: 150–154; Kovařík, 2003: 5–14, figs. 1–8; Kovařík & Ojanguren, 2013: 184–193, 347–354, 357–360, figs. 1265–1367, 1384–1409.

Isometrus ( Raddyanus [sic]): Tikader & Bastawade, 1983: 254–311 (in part), figs. 727–770, 841–895.

TYPE SPECIES. Isometrus acanthurus Pocock, 1899 .

DIAGNOSIS. Medium sized buthids, adults 19–75 mm. Sternum type 1, triangular in shape. Pedipalps orthobothriotaxic, type Aβ. Chelal trichobothrium db located between et and est. Three to five pairs of lateral eyes. Tibial spurs absent on all legs. Pedipalp movable finger with six rows of granules, several accessory granules and external and internal accessory granules. Pedipalp fixed finger with seven rows of granules and six external and seven internal accessory granules. Cheliceral fixed finger with a single ventral denticle. Third and fourth legs with tibial spurs. Tibia and tarsomeres of legs I–III with setae not arranged into bristle combs on dorsal surfaces. Tarsomere II of leg IV with two sparse rows of <20 spiniform setae on ventral surface. Mesosoma dorsally with one median carina. Telson with subaculear tooth pointed or more often rounded. Males of most species have longer metasomal segments and often also a wider pedipalp chela manus than females.

SUBORDINATE TAXA. Currently, 27 species are formally included under the genus (cf. Kovařík & Ojanguren (2013) for information about species not treated here): Reddyanus acanthurus (Pocock, 1899) comb. n., Reddyanus assamensis (Oates, 1888) comb. n., Reddyanus basilicus (Karsch, 1879) comb. n., Reddyanus besucheti (Vachon, 1982) comb. n., Reddyanus bilyi (Kovařík, 2003) comb. n., Reddyanus brachycentrus (Pocock, 1899) comb. n., Reddyanus ceylonensis Kovařík, Lowe, Ranawana, Hoferek, Jayarathne, Plíšková et Šťáhlavský, sp. n., Reddyanus corbeti (Tikader et Bastawade, 1983) comb. n., Reddyanus deharvengi (Lourenço et Duhem, 2010) comb. n., Reddyanus feti (Kovařík, 2013) comb. n., Reddyanus heimi (Vachon, 1976) comb. n., Reddyanus jayarathnei Kovařík, sp. n., Reddyanus jendeki (Kovařík, 2013) comb. n., Reddyanus khammamensis (Kovařík, 2003) comb. n., Reddyanus krasenskyi (Kovařík, 1998) comb. n., Reddyanus kurkai (Kovařík, 1997) comb. n., Reddyanus loebli (Vachon, 1982) comb. n., Reddyanus melanodactylus (L. Koch, 1867) comb. n., Reddyanus navaiae (Kovařík, 1998) comb. n., Reddyanus neradi (Kovařík, 2013) comb. n., Reddyanus petrzelkai (Kovařík, 2003) comb. n., Reddyanus problematicus (Kovařík, 2003) comb. n., Reddyanus ranawanai Kovařík, sp. n., Reddyanus rigidulus (Pocock, 1897) comb. n., Reddyanus tibetanus (Lourenço et Zhu, 2008) comb. n., Reddyanus vittatus (Pocock, 1900) comb. n. and Reddyanus zideki (Kovařík, 1994) comb. n. .

COMMENTS. Vachon (1972: 177) described the subgenus Reddyanus and distinguished it from the nominotypic subgenus Isometrus Ehrenberg, 1828 by the position of chelal fixed finger trichobothria (trichobothrium db located between dt and et in Isometrus, between et and est in Reddyanus). Vachon also cited the different positions of the e 2 trichobothria on the femur (see figs 15, 16 in Vachon, 1972: 176). Subsequently, Vachon (1982) added another character for distinguishing the two subgenera: Isometrus has pedipalp fixed fingers with six rows of granules and six external and internal accessory granules (Figs. 252–253 and figs. 64, 65 in Vachon, 1982: 100), and Reddyanus has pedipalp fixed fingers with seven rows of granules and six external and seven internal granules (Figs. 254–259 and figs. 66 and 67 in Vachon, 1982: 100). Here we propose two additional characters for distinguishing these taxa: (i) ventral aspect of tarsomere II of leg IV with two dense rows of> 30 longer, more filamentous setae in Isometrus (Figs. 196– 197), vs. two sparse rows of <20 shorter, thicker, more spiniform setae in Reddyanus (Figs. 199, 205–208); (ii) hemispermatophore with a relatively short, broad trunk, a short, broad, uncoiled flagellum, and a smaller, blunt basal lobe in Isometrus (Figs. 146–149), vs. a narrow trunk, a long, thin, coiled flagellum and a much enlarged, pointed basal lobe in Reddyanus (Figs. 283– 286). The form of the hemispermatophore of Isometrus appears more similar to that of Lychas (Figs. 183–186), than to Reddyanus . Differences in trichobothriotaxy, pedipalp finger dentition, tarsal setation and hemispermatophore structure provide characters that are useful for higher level classification of buthid scorpions (Kovařík, 2009; Lamoral, 1979; Sissom, 1990; Stahnke, 1972; Stockwell, 198; Vachon, 1952). Taken together, these differences support our taxonomic decision to elevate Reddyanus to a genus distinct from Isometrus .

DISTRIBUTION. Oriental region from India, China (Tibet) to Melanesia.