Molecular cytogenetics of nucleolar organizer regions in Phyllomedusa and Phasmahyla species (Hylidae, Phyllomedusinae): a cytotaxonomic contribution

Abstract

Chromosome numbers, morphology, and nucleolus organizer region (NOR) locations are useful cytological characters for taxonomic and evolutionary studies. In this study, we provide the first cytogenetic analysis of Phyllomedusa bahiana and Phasmahyla spectabilis, and report new cytogenetic data on variation in NOR numbers and positions in Phyllomedusa rohdei and Phyllomedusa nordestina using conventional staining, AgNOR-banding, and 45S rDNA fluorescence in situ hybridization. All 4 species showed 2n = 26 chromosomes. P. spectabilis and P. bahiana had only 1 pair of NOR-carrying chromosomes. P. bahiana showed an NOR length polymorphism, and a rare homomorphic self-compatibility for both NOR lengths in anurans. Variation in the number of NOR-bearing chromosomes was found between the sampled populations of P. nordestina, ranging from 3 to 4. This study also clarified previous conflicting results concerning the occurrence of inter- and intra-population NOR variation in P. rohdei. The variation, confirmed by 45S rDNA fluorescence in situ hybridization analysis, was congruent with results obtained from AgNOR-banding in all species.