Domain Eucaryota
   Subdomain Chlorota Doweld (2001)
     Kingdom Peridiniobiota Starobogatov ex Doweld (2001)
       Subkingdom Parameciobiotina Starobogatov, 1986 [monotypic]
         Phylum Parameciozoa Kussakin & Drozdov, 1998
           Subphylum Oxytrichozoina Doweld, 2001
             Class Spathidiatea Doweld, 2001
               Subclass Spathidiatinea Doweld, 2001
                 1 Order Buetschliida Doweld, 2001 [monotypic]
                 2 Order Spathidiida Foissner & Foissner, 1988
                 3 Order Helicoprorodontida Grain, 1994
                 4 Order Amphileptida Doweld, 2001 [monotypic]
                 5 Order Mesodiniida Grain, 1994