ABSTRACT
BACKGROUND: Dendropsophus is a monophyletic anuran genus with a diploid number of 30 chromosomes as an important synapomorphy. However, the internal phylogenetic relationships of this genus are poorly understood. Interestingly, an intriguing interspecific variation in the telocentric chromosome number has been useful in species identification. To address certain uncertainties related to one of the species groups of Dendropsophus, the D. microcephalus group, we carried out a cytogenetic analysis combined with phylogenetic inferences based on mitochondrial sequences, which aimed to aid in the analysis of chromosomal characters. Populations of Dendropsophus nanus, Dendropsophus walfordi, Dendropsophus sanborni, Dendropsophus jimi and Dendropsophus elianeae, ranging from the extreme south to the north of Brazil, were cytogenetically compared. A mitochondrial region of the ribosomal 12S gene from these populations, as well as from 30 other species of Dendropsophus, was used for the phylogenetic inferences. Phylogenetic relationships were inferred using maximum parsimony and Bayesian analyses. RESULTS: The species D. nanus and D. walfordi exhibited identical karyotypes (2n = 30; FN = 52), with four pairs of telocentric chromosomes and a NOR located on metacentric chromosome pair 13. In all of the phylogenetic hypotheses, the paraphyly of D. nanus and D. walfordi was inferred. D. sanborni from Botucatu-SP and Torres-RS showed the same karyotype as D. jimi, with 5 pairs of telocentric chromosomes (2n = 30; FN = 50) and a terminal NOR in the long arm of the telocentric chromosome pair 12. Despite their karyotypic similarity, these species were not found to compose a monophyletic group. Finally, the phylogenetic and cytogenetic analyses did not cluster the specimens of D. elianeae according to their geographical occurrence or recognized morphotypes. CONCLUSIONS: We suggest that a taxonomic revision of the taxa D. nanus and D. walfordi is quite necessary. We also observe that the number of telocentric chromosomes is useful to distinguish among valid species in some cases, although it is unchanged in species that are not necessarily closely related phylogenetically. Therefore, inferences based on this chromosomal character must be made with caution; a proper evolutionary analysis of the karyotypic variation in Dendropsophus depends on further characterization of the telocentric chromosomes found in this group.
Subject(s)
Anura/genetics , Phylogeny , Animals , Anura/classification , Chromosomes , KaryotypingABSTRACT
A Area de Proteção Ambiental Jundiaí, na Serra do Japi, é uma importante reserva ambiental situada entre duas metrópoles - São Paulo e Campinas - do estado de São Paulo. Trata-se de uma área de grande interesse para a conservação e a pesquisa científica, por se tratar de uma região de transição entre a Mata Atlântica Ombrófila e a Mata Atlântica Estacional Semidecídua do Planalto Ocidental Paulista, abrigando uma grande diversidade de espécies representativas de ambos os ecossistemas. Apesar de ser objeto de estudos desde meados da década de 80, não há nenhuma chave de identificação das espécies da anurofauna disponível para a área até o momento. Trinta e uma espécies de anuros de seis famílias diferentes já foram registradas na vertente do Município de Jundiaí. Apresentamos aqui uma chave dicotômica ilustrada de identificação para os anfíbios anuros da vertente do rio Jundiaí na Serra do Japi.
