Bigyra Cavalier-Smith, 1998
   Subphylum Opalozoa Cavalier-Smith, 1992
     Infraphylum Placidozoa Cavalier-Smith, 2013
       Superclass Wobblata Cavalier-Smith, 2013 [paraphyletic]
         Class Opalomonadea Cavalier-Smith, 2013
           ?Genus Barthelona Bernard, Simpson & Patterson, 2000 [monotypic]
             1 Barthelona vulgaris Bernard, Simpson & Patterson, 2000