Division Haptophyta Hibberd
   Class Prymnesiophyceae D.J. Hibberd (1976) see Class Coccolithophyceae Rothm. (1951)
     Subclass Prymnesiophycidae (D.J. Hibberd) Cavalier-Sm. (1986) see Class Prymnesiophyceae D.J. Hibberd (1976)
       "Nannoliths"
         Family †Triquetrorhabdulaceae Lipps (1969)
           ?Genus †Watkinsia Covington (1994)