Interior Shell Patterns among the Spondylid Species (Bivalvia: Spondylidae) in Mindanao, Philippines

Abstract

The variations among the species of the genus Spondylus were assessed based on its interior shell pattern using landmark- based geometric morphometry. Samples of the Spondylid species were collected and photographed and 15 landmarks from internal shell morphology were quantified and analyzed. Using the Canonical Variance Analysis (CVA) it was able to differentiate into clusters the local Spondylid species. The most distinct characteristic among the Spondylid species is the distance of the pallial line towards the ventral tip of adductor/muscle scar and the size of the cardinal tooth. Multivariate analysis of variance further showed significant differences in the internal shell characters among the Spondylid species across then sampling sites (p<0.05). The internal shell characters among the Spondylid species exhibit disparity despite its great morphological similarity. These shell characters can be used in the identification while conservation efforts are still in the initial stage of the development. The presence of notable dissimilarities in the internal shell characteristics among the Spondylid species indicates that even slight deviations can result in noticeable morphological distinctions. This discovery enhances the understanding of the species divergence within this group and underscores the significance of incorporating internal shell characteristics into taxonomic and ecological investigations.