Microtityus (Microtityus) franckei sp. nov. is described from both male and female specimens from the transition zone of the Tayrona Natural National Park, located in the Caribbean region of Colombia. The new species, which is the first of the genus reported from Colombia, is characterized, among other features, by reductive neobothriotaxy on the pedipalp femur and chela. The new species raises to 25 the number of known species of Microtityus, ten of which are present in continental South America. A revised diagnosis of the genus, a species check-list, and some biogeographic and taxonomic considerations are included.