Phylum Mollusca Linnaeus, 1758 - molluscs
   Class Gastropoda Cuvier, 1795 - snails and slugs
     Subclass Opisthobranchia Milne-Edwards, 1848 - opisthobranchs see Order Opisthobranchia Milne-Edwards, 1848
       Order Nudibranchia Cuvier, 1814 - "true" nudibranchs
         Suborder Arminina Odhner, 1934
           Superfamily Arminoidea Iredale & O'Donoghue, 1923 (1841)
             Family Heterodoridae Verrill & Emerton, 1882, orth. inval. see Family Heterodorididae Verrill & Emerton, 1882
               Genus Atthila Bergh, 1899