MARTIN Gabriel Mario
congresos y reuniones científicas
Systematics of Thylamys, the xeric adapted marsupials of South America
Simposio; 10th International Mammalogical Congress; 2009
Institución organizadora:
Grupo Investigaciones en Biodiversidad / CCT Mendoza / International Federation of Mammalogists
The genus Thylamys includes a group of mouse opossums adapted to xeric environments throughout South America from northeastern Brazil and central PerĂº south to Patagonia, Argentina. I here propose a phylogenetic hypothesis of the genus based on a cladistic analysis of 55 characters (including 3 exosomatic, 21 craniomandibular, 29 dental and 2 molecular) with 13 species of Thylamys plus Micoureus demerarae, Cryptonanus chacoensis and Gracilinanus agilis. Parsimony analysis retained a single tree where Thylamys was recovered as monophyletic, with T. macrurus as the basal species. The most derived forms were the arid-adapted species (e.g., T. elegans, T. pallidior, T. tatei) and the pampas' T. fenestrae, recovered as a sister group to T. cinderella and T. venustus which inhabit the “yungas” of Bolivia and Argentina. T. pusillus is recovered in an intermediate position between T. macrurus + the argentine species T. citellus and T. pulchellus, which inhabit the humid and dry chaco ecosystems, respectively. The Brazilian forms T. karimii and T. velutinus were recovered in an intermediate position, and as the sister group to the most derived arid-inhabiting species + the yungas species.This analysis shows that the genus has adapted to xeric environments on different ocasions, first to “chacoan” ecosystems (e.g., Caatinga, Cerrado and Chaco s.s.), and later on to “andean” (e.g., Monte, Puna) and “subantarctic” (e.g., Patagonia, central Chilean) ecosystems.