Description of the karyotype of Rhagomys rufescens Thomas, 1886 (Rodentia, Sigmodontinae) from Southern Brazil Atlantic forest

Rhagomys rufescens (Rodentia: Sigmodontinae) is an endemic species of the Atlantic forest from Southern and Southeastern Brazil. Some authors consider Rhagomys as part of the tribe Thomasomyini; but its phylogenetic relationships remain unclear. Chromosomal studies on eight specimens of Rhagomys rufescens revealed a diploid number of 2n = 36 and a number of autosome arms FN = 50. GTG, CBG and Ag-NOR banding and CMA3/DAPI staining were performed on metaphase chromosomes. Eight biarmed and nine acrocentric pairs were found in the karyotype of this species. The X and Y chromosomes were both acrocentric. Most of the autosomes and the sex chromosomes showed positive C-bands in the pericentromeric region. The X chromosome showed an additional heterochromatic block in the proximal region of the long arm. Nucleolus organizer regions (NORs) were located in the pericentromeric region of three biarmed autosomes (pairs 4, 6 and 8) and in the telomeric region of the short arm of three acrocentrics (pairs 10, 12 and 17). CMA3/DAPI staining produced fluorescent signals in many autosomes, especially in pairs 4, 6, and 8. This study presents cytogenetic data of Rhagomys rufescens for the first time.

Variações na coloração de iraras (Eira barbara Linnaeus, 1758 - Carnivora, Mustelidae) da Reserva Biológica Estadual do Sassafrás, Santa Catarina, sul do Brasil / Variation in coat color of tayras (Eira barbara Linnaeus, 1758 - Carnivora, Mustelidae) in the State Biological Reserve of Sassafrás, Santa Catarina, South Brazil

Iraras apresentam variações de coloração por toda sua área de distribuição, sendo o objetivo deste estudo contribuir para o conhecimento destas variações. Na Reserva Biológica Estadual do Sassafrás, Santa Catarina, Brasil, foram obtidos 21 registros fotográficos de iraras, abrangendo diferentes colorações de pelagem. Duas classes de coloração foram observadas entre os indivíduos fotografados: corpo escuro com cabeça e pescoço cinzas e corpo, cabeça e pescoço branco-amarelados. A freqüência dos registros não variou significativamente entre as duas classes de coloração, indicando que a coloração de pelagem branco-amarelada é comum para esta população local.

Tayras present color variations along their range of distribution. The objective of this study is to contribute to the understanding of these variations. In the State Biological Reserve of Sassafrás, Santa Catarina, Brazil, 21 photographic records of tayras were obtained, comprising different coat colors. Two coat color classes were observed among photographed individuals: dark body with gray head and neck, and body, head and neck homogeneously white-yellowish. The frequency of records did not varied significantly between the two color classes, indicating that the white-yellowish coloration is common for this local population.