Geometric morphometric analyses of silica-scale variation in four Mallomonas species (Synurophyceae, Stramenopiles)

The tools of geometric morphometrics (GM) were used to examine morphological variation of silica-scales in four Mallomonas species (M. calceolus, M. kalinae, M. flora and M. striata). Relative warps analysis revealed the main trends in morphological variation to be associated with the width, length and shape of the V-rib, while the proximal border region was found to be more stable. Almost all of the scales investigated were successfully differentiated and assigned to an individual species by means of multivariate statistics, the classification experiments were done in a pairwise manner. Geometric morphometric based analyses did not corroborate the classification of these species into traditionally defined sections. M. kalinae and M. striata were found to be the most similar, although they are classified into different sections of the genus, while M. kalinae and M. calceolus that are both traditionally classified as belonging to the section Papillosae, proved to be the most dissimilar species pair.