Bigyra Cavalier-Smith, 1998
   Subphylum Opalozoa Cavalier-Smith, 1992
     Infraphylum Placidozoa Cavalier-Smith, 2013
       Superclass Wobblata Cavalier-Smith, 2013 [paraphyletic]
         Class Placididea Moriya, Nakayama & Inouye, 2002 [monotypic]
           Order Placidida Moriya, Nakayama & Inouye, 2002 [monotypic]
             Family Placidiidae Moriya, Nakayama & Inouye, 2002
               1 Genus Placidia Moriya, Nakayama & Inouye, 2002
               2 Genus Wobblia Moriya, Nakayama & Inouye, 2000