Abstract
The Edentulus clade of the genus Engystomops is composed of E. pustulosus and the E. freibergi-E. petersi species complex, which includes between five and seven species. Three species within this complex exhibit heteromorphic X and Y sex chromosomes, while two others do not present chromosomal sexual heteromorphism. The sex chromosomes of E. pustulosus, the sister species to the E. freibe…