Interspecific morphological variation among members of the genus Cyprinion Heckel, 1843 (Teleostei: Cyprinidae) in Iran, using landmark-based geometric morphometric technique

Morphological variation among Cyprinion species in Iran was studied using landmark-based geometric morphometrics. A total of 848 specimens were caught from five basins throughout Iran during 2013-2015. A total number of 15 landmark-points were defined and digitized on 2D pictures. Despite of intraspecific differences among Cyprinion fishes, CVA divided all populations into three major groups viz. C. macrostomum, C. kais and C. tenuiradius (group X), C. watsoni and C. microphthalmum (group Y) and C. milesi (group Z). According to the results, C. macrostomum group can be distinguished from other groups by having deeper body, least head length and depth, the longest dorsal-fin base and least caudal peduncle length. Cyprinion milesi has the longest anal-fin base, least body depth, deepest caudal peduncle and longest head. Cyprinion watsoni has the longest caudal peduncle and least dorsal-fin base and C. microphthalmum is distinguished by having the least caudal peduncle length and depth. The main reasons of observed intraspecies morphological diversity among the fishes is proposed to be some phenotypic plasticity related to climatic and zoogeographical factors. The results suggest that the most possible factor influencing morphological variations among Iranian Cyprinion species is habitat related differences.