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 Streptaxoidea Gray, 1860 [monotypic]
               Family Streptaxidae Gray, 1860
                 Subfamily Enneinae Bourguignat, 1883
                   Genus Ptychotrema Mörch, 1852
                     1 Subgenus Adjua Chaper, 1885
                     2 Subgenus Excisa Ailly, 1896
                     3 Subgenus Haplonepion Pilsbry, 1919
                     4 Subgenus Ptychoon Pilsbry, 1919
                     5 Subgenus Mirellia Thiele, 1933
                     6 Subgenus Nsendwea Dupuis & Putzeys, 1923
                     7 Subgenus Sphinctostrema Girard, 1894