Sculpting Venus: A geomorphometric analysis of selected species from the family Veneridae (Bivalvia) clams

Abstract

Veneridae, commonly known as Venus clams, is the largest family within phylum Bivalvia, encompassing over 800 species. Recent studies suggest that Veneridae subfamilies exhibit a high similarity in morphological characters, contributing to the taxonomic confusion within this diverse group – remaining poorly understood. However, a few studies have begun using geomorphometric analysis to describe variations in shape and morphology among similar genera of venerids. As such, this study conducted a preliminary geomorphometric analysis of six venerid species: Hyphantosoma nancyae, Liconcha philippinarum, Callista erycina, Paphia declivis, Periglypta puerpera, and Meretrix meretrix. Shell samples were collected from Mindoro Island, a major shellfish producer in the Philippines. The right valves of thirty to thirty-three individuals were subjected to landmark digitization to discriminate among and within species. Thirty-two landmarks were used, fifteen (15) inside and seventeen (17) outlining the shell. The principal component analysis reveals that the antero-ventral and postero-ventral tips of the anterior and posterior cardinal teeth and the postero-ventral tip of the pallial sinus account for the variation inside, while the landmark perpendicular to the junction of the ventral tip of the anterior adductor muscle scar and the pallial line accounts for the variation outlining the shell. Moreover, the canonical variance analysis reveals apparent clustering of individuals of the same species, except for an overlap between C. erycina and P. declivis. The MANOVA also reveals significant shape variation across all species pairs (p = 6.993E-255 < 0.05). This study represents the species differences considering the inside and outline of venerid clams. It highlights the importance of incorporating internal and external shell features for accurate species discrimination within Veneridae.