This is the first record of the presence of Montivipera albizona (Nilson, Andren & Flardh 1990), in Kahramanmaras province, Mediterranean Region of Turkey. Here, one young male specimen was collected and is described. The present record of M albizona extends its known distribution (Kulmac Mountain Range, Sivas) some 250 km to the south-west, where the Anatolian Diagonal exhibits a bifurcation. Our data based on the electropheoretic analysis of blood-sera, indicate that the M. xanthina populations from the western Anatolia and M albizona distributed along the Anatolian Diagonal show significant differences, qualitatively and quantitatively. Accordingly, it is concluded that M albizona should not be included within the polymorphic species M. xanthina which lives in western Anatolia and therefore, it should be accepted as a valid species. Moreover, the actual distributions of the related taxa in Anatolia and the geographic structure of the Anatolian Diagonal were discussed. (C) Koninklijke Brill NV, Leiden, 2009.