High-level systematics and phylogeny of the extant scorpions (Scorpiones: Orthosterni) Author Soleglad, Michael E. Author Fet, Victor text Euscorpius 2003 2003-12-26 2003 11 1 175 http://dx.doi.org/10.18590/euscorpius.2003.vol2003.iss11.1 journal article 10.18590/euscorpius.2003.vol2003.iss11.1 1536-9307 13237351 86191695-B841-4C9D-BFF2-CBC76D1861BA Tribe Chactini Pocock, 1893 Type Genus. Chactas Gervais, 1844 . Composition. The tribe is established here. It includes three genera ( Chactas , Teuthraustes , Vachoniochactas ). Distribution . Central and South America. Taxonomic history . Sissom (2000a) retained the division of Chactas into five subgenera. Biogeographic history . Chactini mainly inhabit the tropical South America, where they exhibit a high diversity ( Table 10 ). A single species, Chactas exsul , is found in Central America ( Panama , Costa Rica ). Diagnosis . Synapomorphies. Chelal finger outer denticles (OD) removed outward from the MD row; chelal finger median denticle (MD) row divided into 7–9 groups; pectinal middle lamellae composed of a single plate or two, semi-fused with anterior lamellae, fulcra quite reduced. Important Symplesiomorphies. Chelal trichobothria Db basal, Dt situated at palm midpoint; patellar trichobothria series em 1 –em 2 and esb 1 proximal of segment midpoint; neobothriotaxy Ch1 present on patellar ventral surface; neobothriotaxy Ch1 present on patellar external surface.