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

CAFFETTI, JACQUELINE D.; RAU, ANGEMARA I.; FENOCCHIO, ALBERTO S.

Foz do Iguazu

Congreso; International Congress of Genetics; 2018

Sociedade Brasileira de Genética

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