Kingdom Plantae Haeckel (1866) - plants
   Subkingdom Rhodoplantae G.W.Saunders & Hommers. (2004)
     Phylum Rhodophyta Wettst. (1901) - red algae
       Subphylum Eurhodophytina G.W.Saunders & Hommers. (2004)
         Class Florideophyceae Cronquist (1960)
           Subclass Hildenbrandiophycidae G.W.Saunders & Hommers. (2004) [monotypic]
             1 Order Hildenbrandiales Pueschel & K.M.Cole (1982)