Domain Eucaryota Subdomain Chlorota Doweld (2001) Kingdom Peridiniobiota Starobogatov ex Doweld (2001) Subkingdom Parameciobiotina Starobogatov, 1986 [monotypic] Phylum Parameciozoa Kussakin & Drozdov, 1998 Subphylum Spirostomozoina Doweld, 2001 Class Spirostomatea Doweld, 2001 [monotypic] Order Spirostomida Doweld, 2001 [monotypic] Family Spirostomidae Stein, 1867 Genus Spirostomum Ehrenberg, 1834