Abstract
A study was conducted on the chromosomes of a Rhamdia hilarii (Pisces, Pimelodidae) population. The results suggest that the basic chromosome number is 2n=58, with numerical variation up to a limit of 2n=63, due to the presence of supernumerary chromosomes which seem to be mitotically stable. These chromosomes are metacentrics and can be different in size. The C-banding pattern, showing heterochromatin especially in both telomeric regions, permits their identification in the karyotype. The NORs are located on secondary terminal constrictions on the short arm of a pair of subtelocentric chromosomes. However, there may be heteromorphism in the size of the secondary constrictions and, consequently, in the size of the NORs.
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Fenocchio, A.S., Bertollo, L.A.C. Supernumerary chromosomes in a Rhamdia hilarii population (Pisces, Pimelodidae). Genetica 81, 193–198 (1990). https://doi.org/10.1007/BF00360864
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DOI: https://doi.org/10.1007/BF00360864