title: The karyotypes of the thorny catfishes Wertheimeria maculata Steindachner, 1877 and Hassar wilderi Kindle, 1895 (Siluriformes: Doradidae) and their relevance in doradids chromosomal evolution.
abstract: We studied the karyotypes of two doradids, the rare and endangered Wertheimeria maculata and a derived Amazonian species, Hassar wilderi. Cytogenetic characterization was assessed using conventional staining (Giemsa), C-banding, and NOR banding. Both species had 2n = 58 chromosomes but differed in their chromosome formulae, 24 m + 14sm + 8st + 12a for W. maculata and 32 m + 16sm + 10st for H. wilderi. In W. maculata heterochromatin was mainly telomeric, and three chromosomes had a fully heterochromatic arm; in H. wilderi heterochromatin was also predominantly telomeric and evident in many more chromosomes. Hassar wilderi also presented one pair of homologues with a fully heterochromatic arm. In both species, nucleolar organizer regions were restricted to one pair of subtelocentric chromosomes. Assuming a basal position for W. maculata, we hypothesized that underlying conserved diploid and NOR-bearing chromosome numbers, chromosomal evolution in doradids has involved pericentric inversions and an increase of heterochromatic blocks.
authors.affiliation: Genética, Conservação e Biologia Evolutiva, Instituto Nacional de Pesquisas da Amazônia, Av André Araújo, 2936, Petrópolis, Manaus, AM, Brazil.
authors.forename: Eduardo S
authors.initials: ES
authors.lastname: Eler
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Dergam
authors.forename: Paulo C
authors.initials: PC
authors.lastname: Vênere
authors.forename: Lílian C
authors.initials: LC
authors.lastname: Paiva
authors.forename: Gabriela A
authors.initials: GA
authors.lastname: Miranda
authors.forename: Alessandro A
authors.initials: AA
authors.lastname: Oliveira
mesh_terms: D000818:Animals; D001938:Brazil; D002397:Catfishes / Q000235:genetics*; D002875:Chromosomes; D019143:Evolution, Molecular; D005260:Female; D007621:Karyotyping; D010802:Phylogeny