ABSTRACT
Introduction to the red algae (Rhodophyta) ..................................................................................104 An ancient and diverse group ............................................................................................104 Unique combination of features ........................................................................................104 Bangiophyceae: relatively simple morphologies...............................................................104 Diverse, complex Florideophyceae....................................................................................105
Ordinal classification has firm foundations ...................................................................................105 Florideophyceae: the enduring legacy of Schmitz and Kylin...........................................105 Bangiophyceae: fewer, less robust orders .........................................................................105 Pit-plug ultrastructure: a crucial catalyst...........................................................................106
Molecular tools and their contribution to systematics ..................................................................106 Pioneer papers ....................................................................................................................106 Molecular phylogenetic markers .......................................................................................107 Higher taxonomic levels: relationship between Bangiophyceae and Florideophyceae ..........................................................................................................108 Ordinal systematics of the Florideophyceae .....................................................................110 Species-level systematics and DNA barcoding .................................................................111
The future of red algal systematics ...............................................................................................113 Molecular markers .............................................................................................................113 Deep-level phylogenetics ...................................................................................................114 Species-level systematics ...................................................................................................115 Speciation research ............................................................................................................116
Acknowledgments ..........................................................................................................................116 References ......................................................................................................................................117
Red algal systematics has a solid morphological foundation, based on analyses of female reproductive structures and post-fertilization development by Kylin and other workers. Recognition of the value of pit-plug ultrastructure was a catalyst leading to refinement of the Kylinian ordinal classification. Molecular approaches to systematics have further advanced our understanding of the red algae at every level and led to the proposal of several new orders. Species diversity in particular has traditionally been underestimated due to the presence of cryptic and pseudo-cryptic species.
