Özet:
This study was carried out from 2008-2016 in order to determine, biogeographic distribution, morphologic and molecular characters and phylogeny of Squalius species in Ceyhan and Lower Euphrates basins. A total of 5 Squalius species determined from two river basin. Squalius kottelati and Squalius spurius determined in Ceyhan basin, Squalius lepidus, Squalius berak and Squalius semae determined in Lower Euphrates basin. Morphometric and meristic characters, cytochrome b (cyt b) gene sequences were determined from 5 Squalius species. All populations for PCA analysis performed on the basis of Ceyhan and the Euphrates basins under study was not pointed to the significant differences in the statistical sense. Squalus spurius, S. berak and S. kottelati are required to be studied in particular using different gene regions and detailed studies should be carried out in order to precisely identify the distribution areas of species.