title: Structural chromosome polymorphism in a Pimelodus maculatus La Cepède, 1803 population (Siluriformes, Pimelodidae) from the Paranapanema River basin, PR, Brazil.
abstract: In the present cytogenetic study of Pimelodus maculatus, 13 specimens (8 males and 5 females) from the Congonhas Stream in Paraná State, Brazil, were examined using conventional staining. All of them showed a karyotype of 2n=56, with a chromosome distribution of 20m + 20sm + 10st + 6a. However, four individuals (2 males and 2 females) were found to have a variant karyotype (cytotype) with two heteromorphic chromosomes in the group of submetacentric chromosomes--one of them corresponds to the second largest chromosome of this group and the other is a chromosome of small size. This variation suggests the existence of a structural polymorphism in the studied population.
authors.affiliation: Departamento de Biologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil.
authors.forename: J
authors.initials: J
authors.lastname: Mazzuchelli
authors.forename: A C
authors.initials: AC
authors.lastname: Swarça
authors.forename: A L
authors.initials: AL
authors.lastname: Dias
mesh_terms: D000818:Animals; D001938:Brazil; D002874:Chromosome Mapping; D020732:Cytogenetic Analysis / Q000379:methods*; D005260:Female; D005399:Fishes / Q000235:genetics*; D007621:Karyotyping; D008297:Male; D011110:Polymorphism, Genetic / Q000235:genetics*