title: Sex chromosome polymorphism in Oryzomys longicaudatus philippii (Rodentia, Cricetidae).
abstract: Oryzomys longicaudatus philippii has a diploid number 2N = 56 (N.F. = 70). A polymorphism of X-chromosomes is described and a duplication as causal mechanism is postulated. The degree of chromosomal differences among the 4 karyological forms of O. longicaudatus and between those forms with O. l. philippii, enable us to postulate the level of full species for all of them.
mesh_terms: D000818:Animals; D005260:Female; D007621:Karyotyping; D008297:Male; D011110:Polymorphism, Genetic; D012377:Rodentia / Q000502:physiology*; D012730:Sex Chromosomes