Geometric analysis of otoliths in Cyprinion kais and Cyprinion macrostomus

Cyprinion macrostomus and Cyprinion kais are species that inhabit in the Tigris River. These fishes, formerly considered as the same species, have been listed as different species by taking differences in jaw and mouth structures into consideration. The mouth shape of C. kais is distinct and small. The mouth is convex and has broad lateral lobes. The mouth of C. macrostomus is wider, is convex and lacks lateral lobes. This study aimed to determine the shape-dependent variability in the breed and sex factors of otoliths of the fish species C. kais and C. macrostomus. For this purpose, 30 right otoliths from both species were used. Geometric morphometric analyses were performed by marking semilandmarks on the otoliths. When examining the results of the analysis, it was found that the first base component accounted for the total shape difference by 26.871% and the first three base components accounted for the total shape difference by 52.235%. In the regression analysis of shape on dimension, it was found that 2.1020% of shape could be estimated in terms of size according to the groups. In the wire-frame wrap graph showing group-based shape differences, it was found that C. kais was wider than C. macrostomus at the level of the dorsal margin and the rostrum region of C. macrostomus was larger and sharply pointed. Consequently, it is believed that the data of the study can be reference for many disciplines, especially for taxonomic classification of species.