The rodent genus Oecomys (Sigmodontinae) comprises ~16 species that inhabit tropical and subtropical forests in Central America and South America. In this study specimens of Oecomys paricola Thomas, 1904 from Belém and Marajó island, northern Brazil, were investigated using cytogenetic, molecular and morphological analyses. Three karyotypes were found, two from Belém (2n = 68, fundamental number (FN) = 72 and 2n = 70, FN = 76) and a third from Marajó island (2n = 70, FN = 72). No molecular or morphological differences were found between the individuals with differing cytotypes from Belém, but differences were evident between the individuals from Belém and Marajó island. Specimens from Belém city region may represent two cryptic species because two different karyotypes are present in the absence of significant differences in morphology and molecular characteristics. The Marajó island and Belém populations may represent distinct species that have been separated for some time, and are in the process of morphological and molecular differentiation as a consequence of reproductive isolation at the geographic and chromosomal levels. Thus, the results suggest that O. paricola may be a complex of species.

Current deforestation practices are likely to result in fragmentation of much of Amazonia. Extreme eastern Amazonia (here referring to the region east of the Tocantins River) is the most populated area of the Brazilian Amazon and, unfortunately, represents the likely future scenario for remaining Amazonia. Although data are available on mammals in central Amazon fragments (the BDFFP project, http://pdbff.inpa.gov.br/), surprisingly little is known about mammalian distribution and responses to fragmentation in eastern Amazonia. As an initial step towards understanding these responses, we compiled available data on mammalian assemblage composition in four fragments east of the Tocantins River, in northeastern Pará, Brazil, between 2002 and 2006. These fragments are privately owned and embedded within a matrix of secondary forest, pasture, slash-and-burn agriculture, and roads. Survey methods included diurnal line transect censusing, nocturnal censusing, live trapping of small mammals, opportunistic observations, and interviews with local informants. Despite environmental stresses, nearly all of the expected large mammalian fauna was recorded at least once, providing reason for optimism. We documented 58 species of mammals in nine orders, and most species we failed to encounter were small nocturnal taxa for which our sampling effort likely was inadequate. Although preliminary in nature, this study highlights the need for comprehensive faunal surveys and complementary ecological research on the fauna of extreme eastern Amazonia. It also indicates that the terrestrial fauna of the region shows indications of resilience in spite of a long history of exploitation.

Little is known about the genus Neusticomys , one of the most poorly represented sigmodontine rodents in scientifi c collections. In this report, we provide new records of Neusticomys ferrerai and N. oyapocki in the Brazilian Amazonia and discuss possible limits for their geographic distributions. Three individuals of N. ferreirai were recorded during three distinct survey events. The fi rst record extends the range of the species approximately 100 km westward, and the other two extend it approximately 1000 km northeastward. For N. oyapocki , our record extends the currently known range of the species approximately 300 km westward. All specimens were collected in primary forests by 60-liter pitfall traps. Considering our records of N. ferreirai and the ecoregions associated with them, we argue that the species range may extends north along the interfl uves Xingu-Tocantins and Madeira-Tapaj ó s and west to the Guapor é River. Similarly, the limits of the range of N. oyapocki may coincide with the Amazon river at south, the Negro river at west and the transition zones between the Guianan forests and savannas or coastal vegetation at east and north. Larger series of Neusticomys in collections are expected to be available in the future, as more inventories using pitfall traps are carried out in Amazonia.

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O controle ambiental de atividades de geração de energia por hidrelétricas de pequeno porte é definido por procedimentos legais previstos em normas federais e estaduais. Entretanto, a falta de regulamentação específica para elaboração dos termos de referência do licenciamento e monitoramentos ambiental comprometem a avaliação dos reais impactos causados pelo empreendimento. O presente estudo analisou os componentes e padrões bióticos adotados nesses termos de referência do licenciamento ambiental de pequenas centrais hidrelétricas, realizado pelo órgão estadual de controle ambiental, com fins de proceder à avaliação dos impactos provocados pela implantação desses empreendimentos e a capacidade de resiliência do meio. Foram revisados os processos de licenciamento ambiental das pequenas centrais hidrelétricas instaladas no Estado do Pará, e a literatura jurídica e ambiental para identificar quais componentes e padrões biológicos são selecionados na elaboração dos termos de referência. Ademais, foi realizada uma análise dos dados do monitoramento dos empreendimentos em operação apresentados à SEMAS-PA. Como resultado tem-se que os processos de licenciamento e monitoramento das pequenas centrais hidrelétricas em operação no Estado do Pará não apresentaram diretrizes formais sobre o processo de resiliência do meio transformado, o que torna a análise ambiental dessas centrais hidrelétricas inviável, dificultando o poder de polícia ambiental no âmbito do Estado.