Comparative cytogenetics of tree frogs of the (Laurenti, 1768) group: conserved karyotypes and interstitial telomeric sequences.

The diploid number 2n = 30 is a presumed synapomorphy of Fitzinger, 1843, although a noticeable variation in the number of biarmed/telocentric chromosomes is observed in this genus. Such a variation suggests that several chromosomal rearrangements took place after the evolutionary origin of the hypothetical ancestral 30-chromosome karyotype; however, the inferred rearrangements remain unknown. Distinct numbers of telocentric chromosomes are found in the two most cytogenetically studied species groups of . In contrast, all three species of the (Laurenti, 1768) group that are already karyotyped presented five pairs of telocentric chromosomes. In this study, we analyzed cytogenetically three additional species of this group to investigate if the number of telocentric chromosomes in this group is not as variable as in other groups. We described the karyotypes of (Cope, 1868), (Caramaschi & Jim, 1983) and (Bokermann, 1968) based on Giemsa staining, C-banding, silver impregnation and hybridization with telomeric probes. , and presented five pairs of telocentric chromosomes, as did the remaining species of the group previously karyotyped. Though the species of this group show a high degree of karyotypic similarity, was unique in presenting large blocks of het-ITSs (heterochromatic internal telomeric sequences) in the majority of the centromeres. Although the ITSs have been interpreted as evidence of ancestral chromosomal fusions and inversions, the het-ITSs detected in the karyotype of could not be explained as direct remnants of ancestral chromosomal rearrangements because no evidence of chromosomal changes emerged from the comparison of the karyotypes of all of the species of the group.