Estudos citogenéticos de espécies de marsupiais (Didelphidae) ocorrentes no cerrado de Aparecida do Rio Negro, Tocantins

Abstract

In the Mammalia class, we have the small non-flying mammals, which are represented by marsupials and rodents. In Brazil, the marsupial fauna is represented by the only existing order in the country, Didelphimorphia, which comprises approximately 56 species, distributed in 15 known genera. Considering that the didelphid marsupials constitute a significant component of the Brazilian mastofauna and that the study of the karyotypes of these animals helps in the recognition and characterization of the species, the present study aimed to identify species of marsupials (Didelphidae), in areas of Cerrado not yet studied, from the cytogenetic point of view, in a joint approach with systematics, morphology and geographical distribution. For this, 9 cell samples were analyzed, which are distributed in the following species: Monodelphis sp., Gracilinanus agilis, Marmosa demerarae, Didelphis marsupialis and Didelphis albiventris, collected at Lagedinho farm, in Aparecida do Rio Negro, Tocantins. The cell samples of these specimens were prepared in slides, whose analyzes allowed to determine the diploid number (2n), number of autosomes (NA), types and forms of chromosomes and C and RON band patterns of all species. The joint analyzes of the cytogenetic, morphological and geographic variations of these taxa in the literature allowed us to obtain the results as follows: Monodelphis sp. (2n = 18 and NA = 30), corroborated with six species of the same genus occurring in other states, but presented variations as to sex chromosomes (X and Y) and C and RON banding patterns. The data indicate that this may be an unprecedented occurrence for the state. The karyotypes of Didelphis albiventris and Didelphis marsupialis (2n = 22 and NA = 20), Micoureus demerarae and Gracilinanus agilis (2n = 14 and NA = 20 and 24, respectively) were, for the most part, the same as those analyzed in studies done in others States. However, in general, they presented differences in karyotypes, as in the patterns of distributions that characterize their location in Tocantins. These situations may be related to chromosomal evolution phenomena, influenced by biotic and abiotic factors.