title: Description of the karyotype of Rhagomys rufescens Thomas, 1886 (Rodentia, Sigmodontinae) from Southern Brazil Atlantic forest.
abstract: 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 CMA(3) /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). CMA (3) /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.
authors.affiliation: Laboratório de Citogenética Animal, Departamento de Genética, Universidade Federal do Paraná, Curitiba, PR Brazil.
authors.forename: André Filipe
authors.initials: AF
authors.lastname: Testoni
authors.forename: Sérgio Luiz
authors.initials: SL
authors.lastname: Althoff
authors.forename: André Paulo
authors.initials: AP
authors.lastname: Nascimento
authors.forename: Francisco
authors.initials: F
authors.lastname: Steiner-Souza
authors.forename: Ives José
authors.initials: IJ
authors.lastname: Sbalqueiro