2.5. Morphological data analysis
A mixed data matrix was created with all morphological characters analysed. For multivariate analysis, a logarithmic transformation was made for quantitative variables (number of oral tentacles, number of longitudinal vessels in folds of the branchial sac, number of longitudinal vessels between the folds of the branchial sac, number of gonads and number of stomach folds). The height and width were not used for this analysis because these two characters are highly variable due to the elastic nature of the animal and the amount of water it contains. Nevertheless, correlation was tested among these two characters and the rest of the studied ones, and no significant relation was found (data not shown). Multivariate analyses were used to determine affinities between specimens of Cnemidocarpa verrucosa based on a morphological character matrix. Nonmetric multidimensional scaling (NMDS) was performed using three dimensions and Gower distance. Nonparametric multivariate analysis of variance (PERMANOVA) was used to assess differences between the groupings obtained in NMDS, each term of the analysis was tested using 9999 permutations. PAST 3.16 free statistical software was used for all the morphological data analyses (Hammer, Harper, & Ryan, 2001).