Cytogenetic characterization of Hoplias malabaricus (Bloch, 1794) from the Ctalamochita River (Córdoba, Argentina) : first evidence for southernmost populations of this species com...

• Autores: Grassi, Diego Javier; Swarça, Ana Claudia; Abdala Dergam, Jorge; Pastori, María Cristina; Fenocchio, Alberto Sergio
• Año de publicación: 2017
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Biogeography; Cytogenetics; Hoplias malabaricus; Karyomorph A
• Institución: Universidad Nacional de Misiones

Fil: Grassi, Diego Javier. The Scripps Research Institute. Department of Molecular Therapeutics; United States.
Fil: Swarça, Ana Claudia. Universidad Estatal de Londrina. Centro de Ciencias Biológicas. Departamento de Histología; Brasil.
Fil: Abdala Dergam, Jorge. Universidad Federal de Viçosa. Departamento de Biología Animal; Brasil.
Fil: Pastori, María Cristina. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Departamento de Genética; Argentina.
Fil: Pastori, María Cristina. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Biología Subtropical; Argentina.
Fil: Pastori, María Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico (Nordeste). Instituto de Biología Subtropical; Argentina.
Fil: Fenocchio, Alberto Sergio. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Departamento de Genética; Argentina.
Fil: Fenocchio, Alberto Sergio. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Biología Subtropical; Argentina.
Fil: Fenocchio, Alberto Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico (Nordeste). Instituto de Biología Subtropical; Argentina.
Hoplias malabaricus (Bloch, 1794), a predatory freshwater fish with a wide distribution throughout South America, represents a species complex with seven well characterized karyomorphs at the cytogenetic level. Although this species has been extensively studied in several Brazilian basins, data are still scarce for hydrographic systems from other South American countries. This study aims to characterize cytogenetically the Hoplias malabaricus populations from the Argentinean Central Region, close to the southernmost distribution of this species complex. A total of 32 specimens from the Ctalamochita River, a tributary of Lower Paraná Basin located in the province of Córdoba, were analyzed using cytogenetic techniques (Giemsa staining, C- and Ag-NOR banding and fluorescent in situ hybridization with 18S rDNA). All the specimens showed diploid number 2n=42, chromosomic formula 22m + 20sm and absence of sexual chromosomes. Thus, the analyzed populations belong to the karyomorph named A. These populations showed a remarkable degree of divergence in their cytogenetic traits such as karyotypic formula, C-banding, NORs and 18S rDNA patterns for Hoplias malabaricus from other populations bearing the same karyomorph in the Middle and Upper Paraná Basin. These findings are consistent with molecular data from a recent study (where specimens collected in the present work were included), which indicate a closer phylogenetic relationship of Hoplias malabaricus populations from the Ctalamochita River with those from the Uruguay basin and the coastal regions of South Brazil than with populations from the Middle and Upper Paraná Basin. Overall, these pieces of evidence highlight the distinctive features of Hoplias malabaricus from the Ctalamochita River, and also reveal a complex history of dispersion of these populations. The present work is the first to provide cytogenetic information and include some phylogeographic aspects of Hoplias malabaricus populations living in close proximity to the southernmost extreme of its distribution area. Therefore, this study expands significantly upon the previously known geographical coverage for karyomorph A and contributes to a better understanding of the karyotypic diversification within this species complex.