 "Gymnodinium" was one of many dinoflagellate genera declared when taxonomic nomenclature was limited to features only visible with the light microscope.In 2000, Hansen and Moestrup analyzed ultrastructural details of the organism using large-subunit (LSU) rDNA sequencing.Aided by this new technology, the scientists were able to declare variations in the path of the apical groove of the organism (found on the flagellar apparatus).