Nemathelminthes Gegenbaur, 1859 see Phylum Nematoda Gegenbaur, 1859
   Class Nematoda Gegenbaur, 1859
     Subclass Secernentia (Von Linstow, 1905) Andrássy, 1976
       Order Tylenchida G. Thorne, 1949
         Suborder Tylenchina Chitwood, 1950
           01 Family Tylenchidae Örley, 1880
           02 Family Atylenchidae Skarbilovich, 1959
           03 Family Psilenchidae Paramonov, 1967
           04 Family Tylodoridae Paramonov, 1967
           05 Family Ecphyadophoridae Skarbilovich, 1959
           06 Family Dolichodoridae Chitwood, 1950
           07 Family Hoplolaimidae Filipjev, 1934
           08 Family Rotylenchulidae Husain & Khan, 1967
           09 Family Pratylenchidae Thorne, 1949
           10 Family Heteroderidae Filipjev & Schuurmans Stekhoven, 1941
           11 Family Meloidogynidae Skarbilovich, 1959
           12 Family Criconematidae Taylor, 1936 (1914)
           13 Family Hemicycliophoridae Skarbilovich, 1959
           14 Family Sphaeronematidae Raski & Sher, 1952
           15 Family Paratylenchidae Thorne, 1949
           16 Family Tylenchulidae Skarbilovich, 1947
           17 Family Neotylenchidae Thorne, 1941
           18 Family Anguinidae Nicoll, 1935 (1926)
           19 Family Iotonchiidae Goodey, 1953