Chactidae Pocock, 1893

Soleglad, Michael E. & Fet, Victor, 2003, High-level systematics and phylogeny of the extant scorpions (Scorpiones: Orthosterni), Euscorpius 2003 (11), pp. 1-175 : 94-95

Family Chactidae Pocock, 1893

Type Genus. Chactas Gervais, 1844 .

Composition. As a result of a considerable revision presented in this paper, the family Chactidae now includes three subfamilies ( Chactinae , Brotheinae , and Uroctoninae ) and 11 genera. The content of Chactidae is

changed here compared to Sissom (2000a). We introduce here the subfamilial division as well as establish tribes and subtribes in Chactinae and Brotheinae . Two new family-group taxa are described: tribe Nullibrotheini and subtribe Neochactina , with a new genus Neochactas . The subfamily Uroctoninae (with genus Uroctonus ) is restored from synonymy and transferred to Chactidae from Vaejovidae , and the genus Anuroctonus is transferred to Uroctoninae from Iuridae (subfamily Hadrurinae ). The genus Belisarius is transferred from Troglotayosicidae to Chactidae (subfamily Brotheinae ), and the subfamily Belisariinae is downgraded to the tribe rank. We also reestablish the nominotypic subfamily Chactinae .

Distribution. Europe, North America, Central and South America.

Taxonomic history. Taxonomic history of Chactidae is given in detail by Sissom (2000a). When first introduced, this family included also Euscorpius (now in Euscorpiidae ), and later incorporated a variety of genera currently placed in Chaerilidae , Euscorpiidae , Iuridae , and Superstitioniidae . The important (but largely unpublished) revision of Stockwell (1989, 1992) elevated Euscorpiidae and Superstitioniidae to family rank, and restricted Chactidae to 10 genera. Sissom (2000a) did not recognize any subfamilies in Chactidae . Soleglad & Sissom (2001) transferred genus Chactopsis from Chactidae to Euscorpiidae .

Biogeographic history. The chactids are predominantly a tropical South American group (see distribution of genera and species in Table 10) However, this family also incorporates four genera, which give it a peculiar disjunct distribution: Nullibrotheas , Anuroctonus and Uroctonus in North America, and Belisarius in Europe (!). These four taxa split the family into a phylogeny, which exhibits a dazzling European-South American disjunction within subfamily Brotheinae . Existence of Belisariini in Europe, and of Nullibrotheini and Uroctoninae in North America indicate an ancient, possibly Pangean age of Chactidae . Monod & Lourenço (2001) note that, with the exception of Chactas keyserlingi (which inhabits dry non-forested mountains in Colombia), all South American chactids are restricted to tropical forests. Disjunct distribution of some South American genera can be attributed to the recent (Pleistocene) fluctuations of tropical rainforest (Lourenço, 1988, 1994, 1996b). In South America, prevalence of the taxa of subfamily Chactinae is observed in northwestern to central areas and those of Brotheinae , in north-central to eastern areas, both overlapping and concentrating in Venezuela, which accounts for over 50% of species (see Table 10). This concentration, however, could be an artifact due to the detailed research of M. A. González-Sponga (1996a, etc.) in Venezuela.

Diagnosis. Synapomorphies. Femur trichobothrium d is positioned equal or distal to i; chelal trichobothrium Eb 1 situated on ventral surface or on V1 carina; genital operculum of female separated for most of its length. Important Symplesiomorphies. Chela trichobothrium it positioned on palm, next to articular membrane of movable finger; chelal trichobothrium eb closest to fixed finger, esb angling toward dorsal edge; patellar trichobothrium v 3 positioned just proximal of or at midpoint of segment and definitely proximal of trichobothria est and et 3; chelal trichobothrium ib situated on extreme fixed finger base or on palm; chelal trichobothria series V 1 –V 4 shorten, V 1 –V 2 –V 3 juncture usually angled toward internal aspect; overall shape of pedipalp chela is rounded; stigma small and oval in shape; number of lateral eyes 0–2.

Characters key to delineating the subfamilies, tribes and subtribes of family Chactidae involve major neobothriotaxy, positions of orthobothriotaxic trichobothria on the chela and patella, the armature of the cheliceral movable finger ventral edge, development of the patella dorsal and ventral spurs (DPS and VPS), and position of the ventroexternal carina of the chela.

Key to the subfamilies, tribes and subtribes of family