Distribution map of snakes similar to Thamnophis scalaris in Mexico. Circles represent museum records; squares represent verified iNaturalist observations, or field observations made by us but without a specimen deposited in a collection. The diamond represents the type locality of Thamnophis ahumadai sp. nov. We have included the different populations of Thamnophis bogerti in the key with their former names in quotation marks, and we used different shades of green to depict their individual ranges.