The changes in shape of the marginal coenobial cells in an experimentally cultured population of Pediastrum duplex Meyen var. duplex were investigated. The methods of landmark-based geometric morphometrics, including sliding landmarks registration, were used. The populations were cultured at 11 different pH levels and the changes in shape related to pH were studied using multivariate regression. The results of relative warps analysis revealed that morphological trends are related to both size and pH. The potential application of the results of this geometric morphometrical analysis of Pediastrum for biomonitoring and palaeoecological studies are discussed.
The relationships of 14 Central European species of the genus Micrasterias were analysed using landmark-based geometric morphometrics. The analysis of relative warps was used to depict the principal components of the variation in shape and cluster analysis to reveal the groupings of individual species within the genus. All the analysed cells were correctly placed in their appropriate species clusters on the basis of geometric morphometric data. The width of the polar lobe associated with depth of the incisions between lateral lobules is the dominant morphological trend in the data investigated.