Elemental Composition and Morphometry of Rhyssoplax olivacea (Polyplacophora): Part II—Intraspecific Variation

Abstract

Rhyssoplax olivacea is a common mediterranean chiton that exhibits great geographic distribution characterized by variability in its abiotic parameters. Using morphometric measurements of the valves and radula, as well as the element composition of its tooth types from individuals sampled from five different regions across the Hellenic seas, intraspecific differences were examined. The relationship between the abiotic factors and elemental composition was also investigated. Hierarchical clustering on principal components (HCPC) was employed separately on the radular and valve characteristics to determine whether these traits can distinguish regions in the form of clusters, while canonical correspondence analysis (CCA) with ANOVA testing were used to examine the effect of temperature, depth and salinity on these features. Both datasets resulted in three clusters; however, investigation of the radula appeared to better distinguish populations among the examined regions, differentiating Kymi and Pagasitikos. The morphometrics of the valves distinguished the North Aegean Sea (Chalkidiki) from the other regions. The CCA reported that the depth, minimum temperature and average salinity influenced the elemental composition of the radular teeth, while the depth and maximum temperature explained variation regarding the valve morphometrics.