Unveiling Shell Geometry: Morphometric Differences Between the Invasive Mussel <i>Perna viridis</i> and the Native <i>Perna perna</i>

Perna viridis is an invasive mussel species recently introduced to the southeastern coast of Brazil, where it coexists with the native Perna perna . Morphological similarity between these species, particularly in early life stages, has led to frequent misidentifications, compromising ecological assessments and management efforts. In this study, we applied geometric morphometrics to compare the shell shape of P . viridis and P . perna using 29 and 33 specimens, respectively, collected from Arraial do Cabo, Rio de Janeiro. Using Procrustes ANOVA, we detected significant shape differences ( F = 20.46, Z = 3.87, p &lt; 0.01), particularly in the umbo, ligament curvature, posterior edge, and inferior margin. Perna viridis exhibited a more elongated and flattened profile, while P. perna displayed a robust, rounded shell. These findings demonstrate the potential of geometric morphometrics to support accurate species identification, essential for ecological monitoring, regulation of shellfish trade, and the development of conservation strategies targeting non‐indigenous species. As P. viridis continues to expand its range along the Brazilian coast, reliable morphological tools are critical for distinguishing it from native species and mitigating its ecological and economic impacts.