Geographic variants of Boana crepitans and Boana xerophylla (Anura, Hylidae, Cophomantini) and their chromosomal diversification process

Boana crepitans and Boana xerophylla are species that, until recently, were a synonym of the former Hypsiboas crepitans. They were previously considered two discontinuous and widely distributed population of B. crepitans across different landscapes in Brazil. We analyzed B. crepitans chromosomes from six localities and B. xerophylla from two, using different chromosomal markers. All individuals of both species presented 2n=24 chromosomes and FN=48. The heterochromatin pattern was variable in B. crepitans from different localities, which allowed us to distinguish different geographical variants. The location of nucleolar organizer regions (NORs) was also variable among populations of B. crepitans, with single markings located in the chromosome pairs 7, 10 and 11, suggesting that NOR may be a valuable taxonomic marker for B. crepitans from each locality already cytogenetically studied, since it presented a unique chromosomal organization, likely product of local adaptation that may be associated to other pre-mating mechanisms which can contribute to geographically differentiation. The B. xerophylla individuals on the other hand, presented a conserved chromosomal organization, which may be related to its occurrence in a more homogeneous environment.