Genus UroctonusThorell 1876
Uroctonus Thorell, 1876a: 11; type species by monotypy Uroctonus mordax Thorell, 1876.
Uroctonus: Thorell, 1876b: 196; Karsch, 1879b: 103; Pocock, 1893: 328; Thorell, 1893: 374; Kraepelin, 1894: 182, 193; Kraepelin, 1899: 182; Pocock, 1902: 14; Comstock, 1912: 30; Ewing, 1928: 12; Hoffmann, 1931: 402; Werner, 1934: 283-284; Mello-Leitão, 1934a: 81; Kästner, 1941: 273; Mello-Leitão, 1945: 128; Gertsch & Allred, 1965: 4; Bücherl, 1971: 329; Gertsch & Soleglad, 1972: 553-568 (part); Hjelle, 1972: 9 (part); Soleglad, 1973b: 351-360 (part); Vachon, 1974: 914, 916; Williams, 1974: 15 (part); Stahnke, 1974a: 119, 129-130, 132, fig. 7A, 8A, 8B, tab. 3, 4; Sissom, 1990a: 111, 114 (part); Williams & Savary, 1991: 272, 274, 284; Stockwell, 1992: 409, 416, 419, fig. 47, 49, 51, 52, 53; Kovarík, 1998: 145; Sissom, 2000:527-528; Soleglad & Fet, 2004: 83-90; Soleglad & Fet, 2003a: 40-43, 57, 58, 84-86, 102-104, 141, figs. 39, 116, 117, Tabs. 3, 4, 9.
Description. - The genus Uroctonus includes medium-sized species with robust, carinated pedipalps. The epigean forms, U. mordax and U. franckei, are dark reddish brown to dark brown in color; the troglophilic U. grahami is pale yellow brown in color.
Prosoma. – Anterior carapacial margin more or less bilobed, with deep rounded anterior median indentation.
Mesosoma. – Pectinal tooth counts 11-15 in males, 8-12 in females. All female pectinal teeth similar in size and shape, and with sensorial areas.
Metasoma. – Dorsal carinae of segments I-IV with even granulation, lacking an enlarged, subspinoid distal denticle. Ventral submedian carinae of segments I-IV paired; on segments I-II obsolete to smooth, on III-IV granular to crenulate. Segment V with bifurcated ventromedian carina. [Note: all metasomal carinae moderately to strongly reduced in U. grahami].
Chelicerae. – Ventral margin of the cheliceral movable finger with 4-7 distinct denticles; fixed finger lacking ventral denticles. Serrula well developed distoventrally on movable finger.
Pedipalps. – Patella: Inner face with three well developed basal tubercles; lacking inner longitudinal carina. Chelal carinae: Ventromedian carina absent, producing flattened ventral chelal face. Dorsomarginal carina granular. Digital and ventroexternal carinae well developed, smooth. [Note: Pedipalpal carinae of U. grahami are considerably reduced]. Chela dentition: Terminal denticles not prominent, conically shaped. Chela fixed finger with primary denticle row divided into six subrows of denticles, these are flanked by seven or eight inner accessory denticles. Chela movable finger with primary denticle row divided into seven subrows of denticles, these flanked by eight or nine inner accessory denticles. Denticles of denticle row subconical, more or less rounded.
Trichobothrial Pattern. Patella with three ventral trichobothria along ventroexternal carina. Four V trichobothria on chela manus. Chelal trichobothrium ib positioned on the distal end of the chela palm, rather than on the fixed finger. Chela trichobothrium est much closer to et than to esb.
Legs. – Basitarsi and telotarsi without setal combs. Telotarsi ventrally with a median row of small spinules that are flanked distally by a pair of slightly larger spinules. Ventromedian spinule row flanked laterally by setae.
Hemispermatophore. – Mating plug absent. Lamellar hook blunt to rounded, positioned at base of ectal edge of distal lamina.
Included species. – U. mordax Thorell, 1876 with two subspecies U. m. mordax Thorell, 1876 andU. m. pluridens Hjelle, 1972;U. franckei Williams, 1986.
Similar taxa. See Pseudouroctonus Stahnke, Uroctonites Williams & Savary, Vaejovis C. L. Koch (mexicanus group).
Remarks. - Once containing most species now in Pseudouroctonus and Uroctonites, this genus has been extensively redefined by various workers and currently includes only 3 species and 1 subspecies (Stahnke 1974; Williams 1980; Williams & Savary 1991; Soleglad & Fet 2004). Soleglad & Fet (2004) provide a key to the species and subspecies. Uroctonus mordax may be encountered under rocks, logs and in burrows along the California coast and into montane forests (the Cascades and Sierras) at elevations ranging from 24-1900 m (Hjelle 1972; Gertsch & Soleglad 1972). Uroctonus franckei is known only from yellow pine forests above 2133 m in the Sierra Nevada. The third species, U. grahami, is troglophilous. We consider Uroctonus to be a vaejovid, and not a chactid, as maintained by Soleglad & Fet (2003, 2004), for reasons provided in the remarks [hyperlink] to family Vaejovidae.
Gertsch, W.J. & Soleglad, M.E. 1972. Studies of North American scorpions of the genera Uroctonus and Vejovis. Bulletin of the American Museum of Natural History 148: 549–608.
Hjelle, J.T. 1972. Scorpions of the northern California coast ranges. Occasional Papers of the California Academy of Sciences 92: 1–59.
Soleglad, M.E. & Fet, V. 2003. High-level systematics and phylogeny of the extant scorpions (Scorpiones: Orthosterni). Euscorpius 11: 1–175.
Soleglad, M.E. & Fet, V. 2004. The systematics of the scorpion subfamily Uroctoninae (Scorpiones: Chactidae). Revista Ibérica de Aracnología 10: 81–128.
Stahnke, H.L. 1974. Revision and keys to the higher categories of Vejovidae. Journal of Arachnology 1: 107–141.
Williams, S.C. & Savary, W.E. 1991. Uroctonites, a new genus of scorpion from Western North America (Scorpiones: Vaejovidae). Pan-Pacific Entomologist 67: 272–287.
Williams, S.C. 1980. Scorpions of Baja California, México, and adjacent islands. Occasional Papers of the Califorinia Academy of Sciences 135: 1–127.