show Abstracthide AbstractTraditionally, dinoflagellates have been defined using morphological characters, although molecular evidence indicates that morphology alone cannot accurately describe all species. This is especially evident in Gambierdiscus, where toxicologically distinct groups have identical morphologies. In order to separate these functionally different organisms, this study sequenced phylogenies from a number of known Gambierdiscus species, as well as one ribotype whose identity had yet been determined. From this data, multigene phylogenies were generated, and rRNA sequences were pulled to create different perspectives to examine the relationships within the Gambierdiscus genus.