title: ZZ/ZW sex chromosome system in an undescribed species of the genus Apareiodon (Characiformes, Parodontidae).
abstract: The chromosomes of an undescribed species of the genus Apareiodon (Characiformes, Parodontidae) from the Verde River, a headwater affluent of the Tibagi River (Paraná State, Brazil), were investigated using conventional Giemsa and Ag stainings, C-banding, CMA(3) fluorescence and fluorescent in situ hybridization (FISH) using 18S and 5S rDNA probes. The diploid chromosome number was 2n = 54, with the karyotype composed of 48 meta/submetacentric and six subtelocentric chromosomes in males, and 47 meta/submetacentric + seven subtelocentric chromosomes in females. The difference is hypothesized to be due to a ZZ/ZW heteromorphic sex chromosome system, a cytotaxonomic characteristic previously observed only in some species of the genus Parodon (family Parodontidae). The presence of similar and/or identical heteromorphic sex chromosome systems might suggest that species of the genera Parodon and Apareiodon bearing ZZ/ZW heteromorphic sex chromosomes likely constitute a monophyletic group, a hypothesis to be tested by a robust phylogeny of the family.
authors.affiliation: Universidade Federal de São Carlos, Depto. de Genética e Evolução, São Carlos, SP, Brazil.
authors.forename: M R
authors.initials: MR
authors.lastname: Vicari
authors.forename: O
authors.initials: O
authors.lastname: Moreira-Filho
authors.forename: R F
authors.initials: RF
authors.lastname: Artoni
authors.forename: L A C
authors.initials: LA
authors.lastname: Bertollo
mesh_terms: D000818:Animals; D005260:Female; D005399:Fishes / Q000145:classification* / Q000235:genetics*; D007621:Karyotyping; D008297:Male; D008677:Metaphase / Q000235:genetics; D012730:Sex Chromosomes / Q000235:genetics*