Abstract
A cytogenetic study of two central Amazonian species of Colostethus with nidicolous tadpoles indicated that Colostethus stepheni had 2n=24 chromosomes, whereas Colostethus nidicola had 2n=22 chromosomes. These species also differed in their NOR localization and C-banding pattern. These results suggest that karyotypic variation with a probable reduction in chromosome number and the presence of nidicolous tadpoles are independent events that may have occurred more than once during dendrobatid evolution.