The Thecal Surface of Some Dinophyceae: A Comparative SEM Approach

Abstract

The micromorphological characters of the theca of some Dinophyceae have been examined by SEM. Different ornamentation types (depressions, pores, ridges and other reliefs) can be detected on the plates. One or more ornamentation patterns may occur on a single plate. Based upon ornamentation types, it has been possible to classify the plates by structural models (from simple to complex). While these structural characters of the plates have been proved to be a useful parameter for distinguishing taxa of lower rank, they are of little significance for the distinction of superior taxa. In fact, plates with different ornamentation patterns may be observed in the same subject and subjects of different genera may have plates exhibiting the same ornamentation. By arranging the various ornamentation types according to their morphological structures (ranging from simple to complex) a certain morphological trend can be determined even though without an evolutive value.