A The dated mitochondrial phylogeny of Natrix tessellata, as adopted from Jablonski et al. (2024), which served as the basis for the division of the morphological and osteological dataset; B The geographic origin of the morphologically investigated specimens of Natrix tessellata from the ‘Greece’ and ‘Europe’ clades, divided, based on the mitochondrial distribution as per Guicking et al. (2009), Asztalos et al. (2021) and Jablonski et al. (2024); C Principal Component Analysis (PCA) of the ‘Europe’ (green) and the ‘Greece’ (purple) clades, based on metric characteristics compared in males and females separately. Most of the variation in the dataset are explained by the first two axes given in %; D Boxplot comparisons of metric characteristics between both clades. Black circles represent means. Asterisks denote the degree of significance ** p < 0.005, *** p < 0.0005; E Linear regression indicating HW rates against SVL rates between males and females of both clades.