Thorellius Soleglad and Fet, 2008

Figures 1E, 5, 7, 17C, D, 20B, 21B; table 1

Vejovis intrepidus Thorell, 1876 [= Thorellius intrepidus (Thorell, 1876)], type species, by original designation.

Vejovis second section (part): Hoffmann, 1931: 134, 139.

Vaejovis second section (part): Francke and González-Santillán, 2007: 590.

Vaejovis intrepidus group (part): Sissom, 1989: 180; 1991: 24, 26; Stockwell, 1992: 409; Sissom, 1993: 68; Lourenço and Sissom, 2000: 135; Sissom, 2000: 537, 538, 551; Armas and Martín-Frías, 2001: 8; Hendrixson 2001: 47; González-Santillán, 2004: 30, 31; Ponce-Saavedra and Sissom, 2004: 539, 541; Graham and Fet, 2006: 7; McWest, 2009: 66, 69, 70, 100–102, table 1; Santibáñez-López and Sissom, 2010: 52.

Vaejovis punctipalpi group (part): Fet et al., 2006a: table 1; Soleglad and Fet, 2006: 6.

Thorellius Soleglad and Fet, 2008: 1, 95, 102 (part); Ayrey and Soleglad, 2011: 1 (part).

DIAGNOSIS: Thorellius may be separated from other genera of Syntropinae by the presence of nine fully developed retroventral macrosetae on the basitarsus of leg III (fig. 21B). Most of the other genera bear six or seven fully developed retroventral macrosetae, the other retroventral setae being smaller (McWest, 2009), whereas Syntropis has more than 10. The pedipalp patellar rlds and rlm carinae are weakly developed and smooth, the dorsal surface of the pedipalp femur finely and sparsely granular, and the ventral surface of the telson vesicle shagreened in all species of Thorellius.

Thorellius is most closely related to Balsateres, gen. nov., with which it shares broad pedipalpal and metasomal carinae. However, the carinae of Thorellius are moderately to densely granular, instead of smooth as in Balsateres, gen. nov. Both sexes of Thorellius, especially the female, exhibit a distinct proximal gap between the fixed and movable fingers, when closed, which is absent in Balsateres, gen. nov. The two genera also differ in base coloration and infuscation. Thorellius are dark and reddish in color, with various degrees of infuscation on the carapace and tergites, whereas Balsateres, gen. nov., is yellow and almost immaculate, except for the ocular tubercle, which is infuscate. Thorellius intrepidus (Thorell, 1876) shares with Balsateres, gen. nov., the presence of double basal prolateral denticles on the movable finger of the pedipalp chela (fig. 20A, B), but is readily separated from the latter by the densely granular carinae and intercarinal surfaces, which are smooth in Balsateres, gen. nov.

Species of Thorellius superficially resemble Kochius, but may be distinguished from the latter by the broad, raised pedipalp carinae, each comprising clustered granules (fig. 17C, D). The pedipalp carinae of Kochius are comparatively shallower and the granulation usually moniliform (fig. 18A, B). The two genera also differ in the macrosculpture of the vsm carinae of metasomal segments I–III, which are costate to weakly denticulate in Thorellius but granular in Kochius.

Thorellius contains the largest and most robust scorpions in the subfamily; the holotype of T. intrepidus is 94 mm in length (Sissom, 2000). Syntropis, the only genus with adults similar in total length, is comparatively slender, with narrow, elongated pedipalps, legs, and metasoma.

INCLUDED SPECIES: Thorellius atrox (Hoffmann, 1931); Thorellius cristimanus (Pocock, 1898); Thorellius intrepidus (Thorell, 1876).

DISTRIBUTION: Thorellius is endemic to Mexico, and recorded from nine states on the mainland: Aguascalientes, Colima, Estado de México, Guanajuato, Guerrero, Jalisco, Michoacán, Nayarit, and Sinaloa (fig. 5). Hoffmann’s (1931) records of T. intrepidus from Veracruz (Catemaco) on the eastern coast of Mexico are probably erroneous; extensive fieldwork has not yielded new collections from this area.

NATURAL HISTORY: There are relatively few data on the ecology of Thorellius. Species of the genus have mostly been collected on the surface at night with UV light detection or by turning stones during the day in subtropical deciduous forest from sea level to 1760 m altitude. As with Mesomexovis, gen. nov., Thorellius species are only active during the rainy season, and estivate during the dry season. Although González-Santillán (2004) suggested that T. intrepidus is pelophilous, the absence of fossorial adaptations suggests otherwise. The habitat and habitus of Thorellius are consistent with the lapidicolous ecomorphotype (Prendini, 2001a).

REMARKS: As redefined here, Thorellius accommodates a subset of species previously assigned to Hoffmann’s (1931) ‘‘second section’’ of Vaejovis, later termed the intrepidus group by Sissom (1989), for which Soleglad and Fet (2008) devised the name Thorellius, without quantitatively testing its monophyly or composition. Thorellius, as defined by Soleglad and Fet (2008), was consistently polyphyletic, and the group of species hereby assigned to it consistently monophyletic, in the phylogenetic analyses of González-Santillán and Prendini (in press) based on morphology and those based on morphology and DNA. The following species are therefore transferred to other genera in the present contribution: Balsateres cisnerosi, comb. nov., previously assigned to Thorellius (Soleglad and Fet, 2008) and the intrepidus group (Santibáñez-López and Sissom, 2010); Mesomexovis occidentalis, comb. nov., and Mesomexovis subcristatus, comb. nov., previously assigned to the intrepidus group (Hoffmann, 1931; Sissom, 2000) and then to Thorellius (Soleglad and Fet, 2008).

MATERIAL EXAMINED: Thorellius atrox (Hoffmann, 1931): MEXICO: Colima: Municipio de Colima: Colima, in house, holotype ♂ of Vaejovis intrepidus atrox Hoffmann, 1931 (AMNH), 18, 1♀ paratypes (AMNH). Thorellius cristimanus (Pocock, 1898): MEXICO: Colima: Municipio de Tonila: Tonila, 3.2 km S, 28.viii.1965, W.J. Gertsch and R. Hastings, 18, 1♀ (AMNH). Thorellius intrepidus (Thorell, 1876): MEXICO: Colima: Municipio de Armería: Mine La Salada, NW Ixtlahuacan, 19 ° 01.680 ′ N 103 ° 47.036 ′ W, 275 m, Mine staff, 18, 1♀ (AMNH). Municipio de Tecomán: Tecomán, 18 ° 54 ′ 30 " N 103 ° 52 ′ 28 " W, 18, 1♀ (AMNH).