XVI International Botanical Congess

Relationships among chrysophyte species and the associated processes generating biological diversity are poorly understood. Of those taxa referred to as chrysophytes, classification at lower taxonomic levels is developed best in the Synurophyceae where morphological variation in siliceous scales is utilized to distinguish taxa. Recent studies from other laboratories use scale morphology and ssu rDNA sequences in phylogenetic or phenetic analyses. Here, ITS/5.8S DNA sequences and a rigorous analysis of character homology from scale development are considered with the previous investigations to identify specific phylogenetic hypotheses. Two ITS types are identified from 17 Synura petersenii isolates originating from 3 continents. Although Synura is polyphyletic, Mallomonas is supported, thus far, as monophyletic. Some characteristics from life history, biogeography or physiology are mapped to clades as hypothetical evolutionary correlates.