Bigyra Cavalier-Smith, 1998
   Subphylum Opalozoa Cavalier-Smith, 1992
     Infraphylum Placidozoa Cavalier-Smith, 2013
       Superclass Wobblata Cavalier-Smith, 2013 [paraphyletic]
         1 Class Placididea Moriya, Nakayama & Inouye, 2002 [monotypic]
         2 Class Nanomonadea Cavalier-Smith, 2013 [monotypic]
         3.1 Class Opalomonadea Cavalier-Smith, 2013