title: Cytogenetic study of heptapterids (Teleostei, Siluriformes) with particular respect to the Nemuroglanis subclade.
abstract: The catfish family Heptapteridae (order Siluriformes) is endemic to the Neotropics and is one of the most common of the fish families in small bodies of water. Although over 200 species have been identified in this family, very few have been characterized cytogenetically. Here, we analyze the chromosome genomes of four species of Heptapteridae: Cetopsorhamdiaiheringi (Schubart & Gomes, 1959), 2n = 58, comprising 28 metacentric (m) + 26 submetacentric (sm) + 4 subtelomeric (st) chromosomes; Pimelodellavittata (Lütken, 1874), 2n = 46, comprising 16m + 22sm + 8st; Rhamdiapropequelen (Quoy & Gaimard, 1824), 2n = 58 comprising 26m + 16sm + 14st + 2 acrocentric; and Rhamdiopsispropemicrocephala (Lütken, 1874), 2n = 56, comprising 12m + 30sm + 14st. The nucleolus organizer regions (NORs) were located in a single chromosome pair in all species. The two species that belonged to the subclade Nemuroglanis, Cetopsorhamdiaiheringi and Rhamdiapropequelen, had a diploid chromosome number of 58 and an interstitial NOR adjacent to a C(+) block located on one of the larger chromosome pairs in the complement. Our results from conventional cytogenetic techniques in combination with FISH using 18S and 5S rDNA probes corroborated the taxonomical hypothesis for the formation of the Nemuroglanis subclade.
authors.affiliation: Taiamã Ecological Station, Chico Mendes Biodiversity Conservation Institute, Mato Grosso, Brazil.
authors.forename: Daniel Luis Zanella
authors.initials: DL
authors.lastname: Kantek
authors.affiliation: Environmental Protection Area Meanders of the Araguaia river, Chico Mendes Biodiversity Conservation Institute, Mato Grosso, Brazil.
authors.forename: Wellington Adriano
authors.initials: WA
authors.lastname: Moreira Peres
authors.affiliation: Laboratory of Molecular Biodiversity and Cytogenetics, Department of Genetics and Evolution, Federal University of São Carlos, São Paulo, Brazil.
authors.forename: Orlando
authors.initials: O
authors.lastname: Moreira-Filho
keywords: 5S and 18S rDNA; Heptapteridae; Siluriformes; chromosomes; cytotaxonomy