Unveiling otolith shape variation: geometric morphometric analysis of three croaker species (Acanthuriformes: Sciaenidae)

In this study, we employed landmark-based geometric morphometric analysis (GMA) of otoliths in 2D to examine inter-species variations within the genus Johnius of the family Sciaenidae collected from the Gopalpur coast of Odisha, India. Our objective was to determine whether otolith shape variation aligns with their morphological uniqueness. A total of 71 left-side otoliths with 14 designated landmarks were considered for GMA. We conducted Principal Component Analysis (PCA), Discriminant Function Analysis (DFA), and Canonical Variate Analysis (CVA) to assess shape variations among Johnius macrorhynus, Johnius dussumieri, and Johnius carutta. Our findings indicate significant shape variation (p < 0.05) among these species' otoliths, consistent with their taxonomic distinctiveness. In conclusion, this study highlights the potential of otolith-based geometric morphometric analysis to enhance taxonomic identification and inform future research on fish diversity and evolutionary dynamics.