Cryptogenic species, those whose native and introduced ranges are unknown, pose a challenge not only to conservation but also to studies of ecology, biogeography, and evolution. One such species is the Lesser Antillean frog, Eleutherodactylus johnstonei, which is broadly distributed through the Caribbean and mainland South America. The Lesser Antilles pose a particular challenge with regard to cryptogenic species because these islands have been anthropogenically connected since before recorded history. We combined genetic (available on...