ABSTRACT
We report the results of small mammals inventories conducted in the region of Jaíba, northern Minas Gerais state, southeastern Brazil, from 1990 to 1995. This region is located in the southern limit of the Caatinga biome, and harbors a unique set of natural ecosystems and extensive agricultural areas. With a total effort of 2964 trap-nights and 44 net sessions, we captured 893 small mammals from 46 species, including four marsupials, 13 rodents, and 29 bats. We report on species that are endemic to the Caatinga (Wiedomys pyrrhorhinos and Xeronycteris vieirai), and species that are new to the mammal fauna of the state of Minas Gerais (Tonatia saurophila, X. vieirai, and Myotis lavali). We also provide the first valid voucher-supported record of Micronycteris sanborni from southeastern Brazil, and extend the known range of X. vieirai 800 km southward. All bats highlighted here as endemic or representing new records were associated to limestone outcrops, suggesting that preservation of this kind of habitat may be particularly relevant to the conservation of these mammals.
Reportamos os resultados de inventários de pequenos mamíferos conduzidos na região de Jaíba, norte de Minas Gerais, sudeste do Brasil, entre 1990 e 1995. Essa região está localizada no limite sul do bioma Caatinga, e abriga um conjunto único de ecossistemas naturais e extensas áreas cultivadas. Com um esforço total de 2964 armadilhas-noite e 44 sessões de captura com redes de neblina, nós capturamos 893 pequenos mamíferos, que permitiram a identificação de 46 espécies, incluindo quatro marsupiais, 13 roedores e 29 morcegos. Nós reportamos espécies endêmicas da Caatinga (Wiedomys pyrrhorhinos e Xeronycteris vieirai) e espécies que são novas para a fauna de mamíferos de Minas Gerais (Tonatia saurophila, X. vieirai e Myotis lavali). Nós também fornecemos o primeiro registro válido, com material testemunho, de Micronycteris sanborni para o sudeste do Brasil, e estendemos a distribuição geográfica conhecida de X. vieirai em 800 km na direção sul. Todos os morcegos destacados aqui como endêmicos ou representando novos registros estiveram associados a afloramentos de calcário, sugerindo que a preservação deste tipo de hábitat pode ser particularmente relevante para conservação desses mamíferos.
ABSTRACT
The genetic variation of Brazilian populations of the mouse opossum Gracilinanus agilis was analyzed on the basis of the mitochondrial Cytochrome b gene (mt-Cytb) and the exon 28 of the nuclear Von Willenbrand factor (e28-vWF). The radiation of Gracilinanus was dated at 4.80 Ma, with the appearance of G. agilis around 1.93 Ma. Gracilinanus aceramarcae appeared as the first offshoot of the genus, followed by Gracilinanus emiliae and Gracilinanus microtarsus, which composed a sister clade of G. agilis. Phylogeographic analyses and genetic distance estimates indicate G. agilis as a single species, with haplotypes grouping in three well-supported clades, one from midwestern Brazil, a second one from northeastern Brazil, and a third one from eastern Brazil. Phylogeographic patterns in G. agilis were interpreted in search for congruence between genetic breaks and historic geomorphologic events documented for the region stretching northeastern to central-western of the Brazilian shield. The Rio São Francisco and the Serra Geral de Goiás were found to represent relevant geographic barriers to gene flow for G. agilis populations as well as for populations of several other widespread taxa.
