ABSTRACT
Introduction ....................................................................................................................................197 General characters..........................................................................................................................198 Life cycle........................................................................................................................................201 Evolution ........................................................................................................................................202 Molecular phylogeny and classification ........................................................................................203 Conclusions ....................................................................................................................................206 Acknowledgments ..........................................................................................................................210 References ......................................................................................................................................210
Cryptomonads have a set of unique morphological and biological features and a fascinating and intricate evolutionary history. Due to their complexity, this group still harbours many mysteries. Different characters were used in the past to derive a unified taxonomic scheme (e.g. colour, cell shape, periplast structure, morphology of the furrow/gullet system, and the phycobilin type). However, views on the phylogenetic value of these characters have changed drastically in the light of results of molecular analyses that have also highlighted the importance of heteromorphic life cycle in this group. Conventional characterization methods have been shown to have limited phylogenetic capacity, whereas the application of new techniques is constrained by the little molecular information so far available for this group of species. The future challenge to fill the current gap in the knowledge of cryptomonads is to combine molecular analyses with improved observational and cultivation techniques.
