The paper discusses the analysis of shape variation in symmetric structures, distinguishing between object symmetry (where a structure is symmetric in itself) and matching symmetry (where two mirror-image structures exist on opposite sides). It introduces a method for partitioning shape variation into symmetric and asymmetric components using Procrustes superimposition and a two-factor ANOVA model. This method is compatible with fluctuating asymmetry studies and allows for the analysis of both symmetric and matching structures. The method is applied to the pharyngeal jaws of the Neotropical cichlid Amphilophus citrinellus, revealing that symmetric variation is dominated by differences between two trophic morphs, while directional asymmetry is subtle but statistically significant. The study emphasizes the importance of considering symmetry in morphometric analyses to avoid statistical issues and provides a framework for testing effects in a two-factor model using MANOVA. The paper also discusses the implications of symmetry for morphological variation, the challenges of analyzing symmetric structures, and the use of geometric morphometrics to study shape variation. It concludes with a case study demonstrating the application of the method to the pharyngeal jaws, highlighting the role of symmetric and asymmetric components in shaping morphological variation.The paper discusses the analysis of shape variation in symmetric structures, distinguishing between object symmetry (where a structure is symmetric in itself) and matching symmetry (where two mirror-image structures exist on opposite sides). It introduces a method for partitioning shape variation into symmetric and asymmetric components using Procrustes superimposition and a two-factor ANOVA model. This method is compatible with fluctuating asymmetry studies and allows for the analysis of both symmetric and matching structures. The method is applied to the pharyngeal jaws of the Neotropical cichlid Amphilophus citrinellus, revealing that symmetric variation is dominated by differences between two trophic morphs, while directional asymmetry is subtle but statistically significant. The study emphasizes the importance of considering symmetry in morphometric analyses to avoid statistical issues and provides a framework for testing effects in a two-factor model using MANOVA. The paper also discusses the implications of symmetry for morphological variation, the challenges of analyzing symmetric structures, and the use of geometric morphometrics to study shape variation. It concludes with a case study demonstrating the application of the method to the pharyngeal jaws, highlighting the role of symmetric and asymmetric components in shaping morphological variation.