Centruroides rileyi Sissom, 1995

Figures 2, 3, 5C, D, 8C, D, 11B, 12B, 17G, J, 18G, J, 19G, J, 20G, J, 21G, J, 22G, J, 23G, J, 24G, J, 25G, G, 26, 27, tables 1, 2, 10

Centruroides rileyi Sissom, 1995: 96–99, figs. 19–27; Armas et al., 2002: 1; 2003: 95; Cancino and Blanco, 2002: 71; Sissom and Hendrixson, 2005: 126, 127, 134, 475; Esposito et al., 2017: 14, 30, fig: 14; 2018: 97, 116; Esposito and Prendini, 2019: 4, fig. 2; Ponce-Saavedra and Francke, 2019: 3; Crews and Esposito, 2020: 14, fig. 11; Goodman and Esposito, 2020: 1–9, fig. 1C (misidentification).

TYPE MATERIAL: MEXICO: Tamaulipas: Município Gómez Farías: Holotype ♂, paratype ♀ (USNM), Bocatoma, 7 km SSE of Gómez Farías, 22°56′30.2″N 99°06′19.3″W, 25–30. iii.1978, E.G. Riley; paratype ♀ (FSCA), Gómez Farías, 16.iii.1977, R. Schmidt. San Luis Potosí: Município Tamazunchale: Paratype ♀ (NAU), 5 km N of Tamazunchale off Hwy 85, 21°18′13.6″N 98°47′58.7″W, 1.viii.1987, J.A. Nilsson.

DIAGNOSIS: Centruroides rileyi is most closely related to C. cuauhmapan, from which it differs as follows. The posterosubmedian carinae of the carapace are weakly developed in C. rileyi (fig. 5A, B), but absent in C. cuauhmapan (fig. 5C, D). The retrodorsal carina of the pedipalp chela manus is smooth, the dorsomedian carina weakly granular, and the prodorsal carina weakly granular and restricted to the distal half of the segment, in the male of C. rileyi (figs. 11, 12A) whereas the retrodorsal carina is finely granular, the dorsomedian carina distinct, granular, and the prodorsal carina distinct, granular and complete in the male of C. cuauhmapan (figs. 11, 12B). The ventrolateral and ventrosubmedian carinae of mesosomal sternite VII are obsolete to absent and the intercarinal surfaces smooth in C. rileyi, whereas the ventrolateral and ventrosubmedian carinae are distinct, granular and the intercarinal surfaces finely granular in C. cuauhmapan . The metasoma and telson are shorter in the male and slenderer, proportionally shorter and narrower, in the female of C. rileyi (figs. 17A, D, 18A, D, 19A, D, 20A, D, 21A, D, 22A, D, 23A, D, 24A, D, 25A, D, table 2) than C. cuauhmapan (figs. 17G, J, 18G, J, 19G, J, 20G, J, 21G, J, 22G, J, 23G, J, 24G, J, 25G, J, table 3). The ventral carinae are granular on metasomal segment I in the female, vestigial on segments I–III and smooth on IV and V in the male of C. rileyi (figs. 18A, D, 19A, D, 20A, D, 21A, D, 22A, D) but distinct, granular on segments I–V in the male and female of C. cuauhmapan (figs. 18G, J, 19G, J, 20G, J, 21G, J, 22G, J). The surfaces of the telson vesicle of the female are smooth in C. rileyi (figs. 24A, D, 25A, D) but granular in C. cuauhmapan (figs. 24G, J, 25G, J).

TABLE 9 continued

1 Sum of carapace, tergites I–VII, metasomal segments I–V, and telson; 2 distance between median ocelli; 3 sum of trochanter, femur, patella, and chela; 4 measured from base of condyle to tip of fixed finger; 5 sum of tergites I–VII; 6 sum of metasomal segments I–V and telson.

VARIATION: Adult males and females differ as follows. The dorsomedian carinae of the pedipalp patella are absent, the mesosoma proportionally longer and slenderer, and the metasoma longer, in males (figs. 26A, B, 27A, B, 28A, B, 29A, B, table 2). The first pair of legs are longer in males and the metasomal carinae more pronounced and finely serrate in females (figs. 17A, D, 18A, D, 19A, D, 20A, D, 21A, D, 22A, D, table 2).

DISTRIBUTION: Centruroides rileyi is endemic to northern Mexico, east of the Sierra Madre Oriental. The species is fairly widespread, with records from the states of Puebla, Tamaulipas, San Luis Potosí, and Veracruz (fig. 3).

ECOLOGY: The localities at which C. rileyi has been recorded range in altitude from 100 to 2554 m. The habitat at these localities varies from subtropical and semi-deciduous forests near the El Cielo Biosphere Reserve, Tamaulipas, to tropical and subtropical moist broadleaf forest at La Sierra Gorda, San Luis Potosí, and tropical humid moist forest in Veracruz (Mendoza-Villa et al., 2018). The habitat and habitus are consistent with the arboreal, corticolous ecomorphotype (Prendini, 2001a).

REMARKS: Centruroides rileyi has never been confused with other species of the “ thorellii ” clade nor with C. thorellii, perhaps due to its occurrence in northern Mexico. Furthermore, the small size and distinctive mottling pattern contrast with other buthids, such as Centruroides gracilis (Latreille, 1804) and Centruroides vittatus (Say, 1821), that occur in sympatry (Shelley and Sissom, 1995).

MATERIAL EXAMINED: MEXICO: Puebla: Município Cuetzalan el Progreso: Cuetzalan, Santiago Yancuitlalpan, 18°54′ 42.2″ N 98°35′15.3″W, 2554 m, 19.v.1995, G. Oclogaig Barrzia, juvs (CNAN SC3999). San Luis Potosí: Município Axtlan de Terrazas: Axtlan de Terrazas, 21°25′34.9″N 98°52′42″W, 100 m, 28.iv.2006, O.F. Francke, A. Valdez, G. Villegas and R. Paredes, 1 ♂ (AMNH [LP 6445]), 1 ♀, 2 juv. ♀ (CNAN SC4003). Veracruz: Município Papantla: Papantla, 20°27′24.1″N 97°18′56.1″W, 2197 m, iii.2000, J.L. Castelo, 1 ♂ (CNAN SC4000). Município Tamiahua: Moralillo, Cerro Azul, 21°11′03.8″N 97°44′49.6″W, 153 m, 27.ii.2007, E. Barrera and L. Cervantes, 2 ♀ (CNAN SC3985), 1 juv. ♀ (CNAN SC4002).