First cytogenetic characterization of the native mussel Diplodon cf. rhuacoicus (Mollusca: Bivalvia) in Northeastern Argentina

FENOCCHIO, AS; RAU, AI; CAFFETTI JD

Foz do Iguaçu

Congreso; 2018 International Congress of Genetics; 2018

Latin American Association of Genetics, Sociedade Brasileira de Genética e International Genetics Federation

Introduction: Argentina represents the second hydrographic region with the greatest species richness of native freshwater mussels. Bivalves of the Neotropical Region are included in two families widely spread, Hyriidae and Etheriidae. The genus Diplodon belongs to Hyriidae family and they are represented by 17 species in La Plata river basin. These species are susceptible to environmental pollution and their habitat to invasion of exotic bivalves. Objectives: This study aims to describe for the first time the Diplodon cf. rhuacoicus karyotype, in order to contribute with new cytogenetic data. Materials and Methods: Eleven specimens D. rhuacoicus were collected in Uruzú, Ramos and Cuña Pirú streams (Misiones, Argentina). Chromosome preparations were obtained by means of cell suspension from gonads and gills tissues. Metaphases were analyzed by conventional and differential staining (Ag-NOR and C banding). Results and Conclusions: All analyzed specimens presented a diploid chromosome number of 2n= 34 (FN= 68). Karyotypic formulae shows 9 pairs of metacentric and 8 pairs of submetacentric chromosomes. Ag-NOR staining revealed 4 active NORs, localized on terminal region of long arms of at least 1 pair of metacentric and other submetacentric. The visualization of C-bands showed positive regions at the centromeres of most chromosomes. Additionally, telomeric C-bands were observed in some chromosomes. This study contribute significantly to the cytogenetics of the genus Diplodon, in view of the scarce number of this kind of studies in South America. In addition, the data obtained associated with other studies could help to elucidate the controversial taxonomic problems of the group.