title: Description of karyotype in Hypostomus regani (Ihering, 1905) (Teleostei, oricariidae) from the Piumhi river in Brazil with comments on karyotype variation found in Hypostomus.
abstract: The paper represents a comparative cytogenetic analysis of three populations of Hypostomus regani in Brazil.Two populations belong to the Upper Paraná River Basin and the third one, the karyotype of which is described for the first time, was probably introduced into the São Francisco River Basin through transposition from the Piumhi River. Karyotype features of populations of Hypostomus regani from the Piracicaba and Tietê River Basins are also discussed. The occurrence of Hypostomus regani in the São Francisco River Basin is reported for the first time here. The study also revealed distinct differences in the location of the Ag-NORs between the analyzed populations that enable individuals from the Piumhi River, Mogi-Guaçu River and Tietê River to be distinguished from one another. Thus, the data obtained indicate the possibility of geographic variation fixing different karyotypes even in the same basin of origin.
authors.affiliation: Universidade Federal de São Carlos. Depto. Genética e Evolução. São Carlos, SP, Brazil.
authors.forename: Ernani de Oliveira
authors.initials: Ede O
authors.lastname: Mendes-Neto
authors.forename: Marcelo Ricardo
authors.initials: MR
authors.lastname: Vicari
authors.forename: Roberto Ferreira
authors.initials: RF
authors.lastname: Artoni
authors.forename: Orlando
authors.initials: O
authors.lastname: Moreira-Filho
keywords: cytotaxonomy; karyotype diversification; rDNA