Cytotaxonomy of Iberian loaches with some remarks on the karyological evolution of both families (Pisces, Cobitidae, Homalopteridae)

SUMMARY

The three species of cobitoids inhabiting the Iberian Peninsula were cytogenetically analysed—Cobitis calderoni, C. maroccana and Nemacheilus barbatulus. Metaphasic plates of specimens collected in several Portuguese and Spanish streams and, for the stoneloach, also in a central European river, were compared. All the species have a diploid value of 2n = 50 and are characterized by a high incidence of chromosomes with terminal/subterminal centromeres, particularly the cobitids. In spite of their phenotypical distinction, the spined-loaches karyotypes are grossly similar, suggesting only the occurrence of punctual chromosome rearrangements related to the respective differentiation processes. The lack of well-apparent interpopulation chromosome variability and the existence of diploid-polyploid relationships in these Euro-Asiatic families is finally discussed according to the new model of Cyprinidae karyological evolution.