A 13-landmark morphometric truss network system was used to investigate the hypothesis of population fragmentation of Aphanius dispar (Pisces: Cyprinodontidae) from Ahram and Dalaki rivers in Bushehr, south of Iran. A total of sixty specimens were caught from the rivers . Principal component analysis (PCA), Discriminant function analysis (DFA) and clustering analysis (CA) were used to examine morphological differences. The PCA, scatter plot of individual component score between PC1 and PC2, showed that the specimens are grouped into two areas but with high and moderate overlap between two localities. Univariate analysis of variance showed significant differences between the means of the two groups for 42 standardized morphometric measurements out of 78 characters studied. CA indicated different populations of A. dispar in Ahram and Dalaki rivers. These populations of A. dispar are distinguished especially by pre anal, body height, distance from pectoral fin to ventral fin, distance from pectoral fin to anal fin, caudal peduncle length, head length, pre orbital, pre ventral, and dorsal length. Therefore, it is suggested considering these morphologically different populations as distinct stock in the studied rivers.
A. dispar, Truss network system, Population, Morphological divergence.