Open Access

W. David Sissom, Scott A. Stockwell

• Taxonomic characters of the recently resurrected scorpion genus Serradigitus Stahnke are discussed, leading to changes in the diagnosis and composition of the genus. Four species, S. baueri (Gertsch), S. bechteli (Williams), S. littoralis (Williams), and S. pacificus (Williams) are transferred into Serradigitus from the genus Vaejovis. The diversity of Serradigitus and distribution of its species in the Mexican state of Sonora are investigated. Serradigitus hearnei (Williams) and S. subtilimanus (Soleglad) are reported for the first time there, and four new species are described (two of which also occur in the United States): S. allredi from southern Arizona and central Sonora; S. polisi from Isla Tiburon and the Kino Bay area; S. yaqui from coastal Sonora, and S. agilis from southeastern Arizona, southwestem New Mexico, and eastern Sonora. A record for S. harbisoni (Williams) is referred to S. polisi. A key to the Serradigitus species of Sonora is provided.