Dichotomous key and distribution of the Stenocereus griseus species complex (Cactaceae)

In order to distinguish species that are part of the Stenocereus griseus complex (Cactaceae), we reviewed morphological characters and geographic data from herbarium specimens and records on biodiversity databases. Morphological features of 307 specimens deposited in 7 herbaria were registered and geographical records were projected through geographic information system, considering both political divisions and physiographic regionalization. Nineteen diagnostic characters were detected, through them, a dichotomous key was generated which is capable of distinguishing the Stenocereus griseus complex members from each other and from other Stenocereus. The key is supplemented with complete descriptions and photographs. In addition, maps were generated in order to update the knowledge of the Stenocereus griseus complex distribution as well as their biogeographical associations. The products generated are intended to be useful taxonomic tools for this complex species group.