Discriminant-based study of the shell morphometric relationships of Patella caerulea (Gastropoda: Prosobranchia) of the western Mediterranean Sea

Abstract

Our work is a contribution to the study of the morphometric dissimilarity of the limpet Patella caerulea (Linnaeus, 1758) inhabiting the seashore of the western Mediterranean Sea. For this study, 438 individuals of this species were sampled in 24 stations and separated into 2 groups of individuals: the first group (G1) originating from the upper infralittoral and the lower mediolittoral areas, and the second group (G2) originating from the upper mediolittoral area. The biometry of P. caerulea has been studied by considering the total length (L), the total width (W), and the total height (H) of the shell. These parameters revealed a strong positive correlation, and were used for the principal component analysis (PCA). Other combined parameters (L/W, L/H, and W/H) were added for the discriminant function analysis (DFA). Both multivariate analyses showed that both groups (G1 and G2) were well separated. The morphometric survey based on the calculation of the geometric mean (GM) and the gibbosity index (GIB) revealed the existence of a morphological dissimilarity between the shells of groups G1 (flattened and stocky) and G2 (high and short). This morphological dissimilarity is discussed and compared with the results of other works on the same species and other related species.