Ablechroiulidae Andrássy, 1976 (extant flag source)
Ablechroiulidae Andrássy, 1976 (current name source)
Ablechroiulidae Andrássy, 1976 (habitat flag source)
Ablechroiulidae Andrássy, 1976 (basis of record)
Achromadoridae Gerlach & Riemann, 1973 (current name source)
Achromadoridae Gerlach & Riemann, 1973 (habitat flag source)
Actinolaimidae Thorne, 1939 (habitat flag source)
Actinolaimidae Thorne, 1939 (current name source)
Acuariidae Railliet, Henry & Sisoff, 1912 (habitat flag source)
Acuariidae Railliet, Henry & Sisoff, 1912 (current name source)
Acugutturidae Hunt, 1980 (basis of record)
Acugutturidae Hunt, 1980 (extant flag source)
Acugutturidae Hunt, 1980 (current name source)
Acugutturidae Hunt, 1980 (habitat flag source)
Adenophorea (current name source)
Aegialoalaimidae Lorenzen, 1981 (habitat flag source)
Aegialoalaimidae Lorenzen, 1981 (current name source)
Aetholaimidae Jairajpuri, 1965 (habitat flag source)
Aetholaimidae Jairajpuri, 1965 (current name source)
Agfidae Dougherty, 1955 (current name source)
Agfidae Dougherty, 1955 (habitat flag source)
Alaimida (current name source)
Alaimidae Micoletzky, 1922 (habitat flag source)
Alaimidae Micoletzky, 1922 (current name source)
Alirhabditidae Suryawanshi, 1971 (current name source)
Alirhabditidae Suryawanshi, 1971 (habitat flag source)
Allantonematidae Pereira, 1931 (current name source)
Alloionematidae Chitwood & McIntosh, 1934 (current name source)
Alloionematidae Chitwood & McIntosh, 1934 (habitat flag source)
Anatonchidae Jairajpuri, 1969 (habitat flag source)
Anatonchidae Jairajpuri, 1969 (current name source)
Anatrichosomatidae Yamaguti, 1961 (current name source)
Anatrichosomatidae Yamaguti, 1961 (habitat flag source)
Ancylostomatidae Looss, 1905 (current name source)
Andrassyidae Tchesunov & Gagarin, 1999 (habitat flag source)
Andrassyidae Tchesunov & Gagarin, 1999 (current name source)
Angiostomatidae Blanchard, 1895 (current name source)
Anguillicolidae Yamaguti, 1935 (current name source)
Anguinidae Nicoll, 1935 (current name source)
Anisakidae Railliet & Henry, 1912 (current name source)
Anoplostomatidae Gerlach & Riemann, 1974 (habitat flag source)
Anoplostomatidae Gerlach & Riemann, 1974 (current name source)
Anticomidae Filipjev, 1918 (current name source)
Anticomidae Filipjev, 1918 (habitat flag source)
Aphanolaimidae Chitwood, 1936 (current name source)
Aphasmida (current name source)
Aphelenchida accepted as Panagrolaimida (source of synonymy)
Aphelenchidae Fuchs, 1937 (habitat flag source)
Aphelenchidae Fuchs, 1937 (current name source)
Aphelenchoididae Skarbilovich, 1947 (current name source)
Aphelenchoididae Skarbilovich, 1947 (habitat flag source)
Aponchiidae Gerlach, 1963 (habitat flag source)
Aponchiidae Gerlach, 1963 (current name source)
Aporcelaimidae Heyns, 1965 (current name source)
Aproctidae Yorke & Maplestone, 1926 (current name source)
Araeolaimida accepted as Monhysterida (source of synonymy)
Ascaridae Baird, 1853 accepted as Ascarididae Baird, 1853 (source of synonymy)
Ascaridida accepted as Spirurida (source of synonymy)
Ascaridiidae Travassos, 1920 (current name source)
Aspidoderidae Skrjabin & Schikhobalova, 1947 (current name source)
Atractidae Railliet, 1917 (current name source)
Atylenchidae Skarbilovich, 1959 (current name source)
Aulolaimidae Jairajpuri & Hopper, 1968 (current name source)
Aulolaimidae Jairajpuri & Hopper, 1968 (habitat flag source)
Aulolaimoididae Jairajpuri, 1964 (current name source)
Aulolaimoididae Jairajpuri, 1964 (habitat flag source)
Axonolaimidae De Coninck & Schuurmans Stekhoven, 1933 (habitat flag source)
Axonolaimidae De Coninck & Schuurmans Stekhoven, 1933 (current name source)
Bastianiidae De Coninck, 1935 (current name source)
Bastianiidae De Coninck, 1935 (habitat flag source)
Bathyodontida (current name source)
Bathyodontidae Clark, 1961 (habitat flag source)
Bathyodontidae Clark, 1961 (current name source)
Belondiridae Thorne, 1939 (current name source)
Belonolaimidae Whitehead, 1959 (current name source)
Benthimermithida (current name source)
Benthimermithidae Petter, 1980 (current name source)
Benthimermithidae Petter, 1980 (habitat flag source)
Berntsenidae Hodda, 2003 (basis of record)
Berntsenidae Hodda, 2003 (habitat flag source)
Berntsenidae Hodda, 2003 (current name source)
Berntsenidae Hodda, 2003 (extant flag source)
Bicirronematidae Andrássy, 1978 (habitat flag source)
Bicirronematidae Andrássy, 1978 (current name source)
Bodonematidae Jensen, 1991 (current name source)
Boleodoridae Khan, 1964 (current name source)
Brevibuccidae Paramonov, 1956 (current name source)
Bunonematidae Paramonov, 1956 (current name source)
Camacolaimidae De Coninck & Schuurmans Stekhoven, 1933 (current name source)
Camacolaimidae De Coninck & Schuurmans Stekhoven, 1933 (habitat flag source)
Camallanida accepted as Spirurida (source of synonymy)
Camallanidae Railliet & Henry, 1915 (habitat flag source)
Camallanidae Railliet & Henry, 1915 (current name source)
Campydoridae Clark, 1961 (current name source)
Capillariidae Railliet, 1915 (current name source)
Capillariidae Railliet, 1915 (habitat flag source)
Carabonematidae Stammer & Wachek, 1952 (current name source)
Carcharolaimidae Thorne, 1967 (current name source)
Carnoyidae Filipjev, 1934 (extant flag source)
Carnoyidae Filipjev, 1934 (current name source)

 Taxonomic remark

 for Diplogastridae

Hodda (2011) and Ruggiero et al. (2014) use spelling Diplogasteridae, although this spelling (Diplogastridae) is ... [details]