Kingdom [Animalia] Linnaeus, 1758 - animals
   Subkingdom Protozoa Goldfuss, 1818 see Kingdom Protozoa Goldfuss, 1818
     Class Ciliata see [unranked] ciliates
       Order Holotricha
         Suborder Gymnostomata
           Genus [Didinium] Stein, 1859
             Didinium nasutum (O.F. Müller, 1773) Stein, 1859