Phylum Mollusca Linnaeus, 1758 - molluscs
   Class Gastropoda Cuvier, 1795 - snails and slugs
     Subclass Divasibranchia Minichev & Starobogatov, 1975
       Order Stylommatophora Schmidt, 1855 see Infraorder Stylommatophora Schmidt, 1855
         (Achatinid Sigmurethra)
           Suborder Sigmurethra Pilsbry, 1900 see Group Sigmurethra Pilsbry, 1900
             Superfamily Punctoidea Morse, 1864
               Family Discidae Thiele, 1931 (1866)
                 Genus Discus Fitzinger, 1833
                   1 Subgenus Discus Fitzinger, 1833
                   2 Subgenus Antediscus Baker, 1948
                   3 Subgenus Atlantica Ancey, 1887
                   4 Subgenus Calogoniodiscus Pfeffer, 1929
                   5 Subgenus Keraea Gude, 1911
                   6 Subgenus Mexicodiscus Pilsbry, 1926
                   7 Subgenus Nanopatula Pfeffer, 1929
                   8 Subgenus Nematodiscus Pilsbry, 1948