Bigyra Cavalier-Smith, 1998
Count: [*] 6c;10o;21f;34g;8s
   Subphylum Opalozoa Cavalier-Smith, 1992
  Count: [*] 6c;10o;20f;33g;6s [15 Mar 2016]
     Infraphylum Placidozoa Cavalier-Smith, 2013
    Count: [*] 5c;5o;7f;12g;2s [15 Mar 2016]
       Superclass Opalinata Wenyon, 1926
      Count: [*] 2c;3o;4f;6g [15 Mar 2016]
         Class Opalinea Wenyon, 1926
        Count: [*] 2o;3f;5g [15 Mar 2016]
           Order Proteromonadida Grassé, 1952 [monotypic]
          Count: [*] 1f;1g [15 Mar 2016]
             1 Family Proteromonadidae Grassé, 1952 [monotypic]
            Count: [*] 1g [15 Mar 2016]