Landmark-Based Morphological Differences Among the Exotic Rhinogobius lindbergi and Its Two Sympatric Gobies (Actinopterygii: Perciformes: Gobiidae) in Sefid River, in the Southern Caspian Sea Basin

Introduced species may cause harm to native fish populations, which to design any conservative program to control the exotics an identification key is necessary. To find the morphological differences among the exotic Rhinogobius lindbergi and its sympatric congeners including the endemic Ponticla iranicus and the native Ponticla gorlap, a 15-landmark morphometric system was used to examine 90 specimens in Sefid River, in the Southern Caspian Sea basin. Univariate analysis of variance showed significant differences among the means of the three groups for 79 out of 105 standardized morphometric measurements. Principal component analysis (PCA) and canonical variates analysis (CVA) confirmed the statistically significant difference among these species. The CVA scatter plot showed that the 90 studied specimens grouped into three distinct areas with a degree of overlap between P. iranicus and P. gorlap. Clustering based on Euclidean distances among the groups of centroids using an UPGMA indicated segregation of the three species into two distinct clusters: P. iranicus and P. gorlap in one group and R. lindbergi in the other group. The exotic Rhinogobius can be distinguished from the sympatric gobies in Sefid River by short snout (vs. longer), deep body (vs. shallow), deeper head, stout body, and smaller ventral disc.