Acanthonchus viviparus Cobb, 1920 accepted as Acanthonchus (Acanthonchus) viviparus Cobb, 1920 (additional source)
Acanthopharyngoides Chitwood, 1936 (additional source)
Acanthopharyngoides tyrrhenicus Wieser, 1954 (additional source)
Acanthopharynx affinis Marion, 1870 (additional source)
Acanthopharynx micans (Eberth, 1863) Marion, 1870 (additional source)
Acanthopharynx micramphis Schuurmans Stekhoven, 1942 (additional source)
Acanthopharynx perarmata Marion, 1870 (additional source)
Acanthopharynx rigida Schuurmans Stekhoven, 1950 (additional source)
Acanthopharynx setosissima Schuurmans Stekhoven, 1943 (additional source)
Achromadora buikensis (Steiner, 1921) Micoletzky, 1925 accepted as Achromadora micoletzkyi (Stefanski, 1915) Micoletzky, 1925 (basis of record)
Achromadora dubia sensu Micoletzky, 1925 accepted as Achromadora inermis Altherr, 1952 (basis of record)
Achromadora inermis Altherr, 1952 (basis of record)
Achromadora micoletzkyi (Stefanski, 1915) Micoletzky, 1925 (basis of record)
Achromadora ruricola (De Man, 1880) Micoletzky, 1924 (basis of record)
Achromadoridae Gerlach & Riemann, 1973 (basis of record)
Achromadorinae Gerlach & Riemann, 1973 (basis of record)
Actinonema Cobb, 1920 (additional source)
Actinonema celtica Boucher, 1976 (additional source)
Actinonema fidatum Vitiello, 1970 (additional source)
Actinonema longicaudatum (Steiner, 1918) Wieser, 1954 (additional source)
Actinonema pachydermatum Cobb, 1920 (additional source)
Adeuchromadora Boucher & De Bovée, 1971 accepted as Actinonema Cobb, 1920 (additional source)
Adeuchromadora megamphida Boucher & Bovée, 1972 accepted as Actinonema pachydermatum Cobb, 1920 (additional source)
Adoncholaiminae Gerlach & Riemann, 1974 (additional source)
Aegialoalaimidae Lorenzen, 1981 (additional source)
Aegialoalaimus de Man, 1907 (additional source)
Aegialoalaimus elegans de Man, 1907 (additional source)
Aegialoalaimus punctatus (Allgén, 1929) (additional source)
Aegialoalaimus tenuicaudatus Allgén, 1932 (additional source)
Aegialoalaimus tenuis Kreis, 1928 (additional source)
Alaimella Cobb, 1920 (additional source)
Alaimella cincta Cobb, 1920 (additional source)
Alaimidae Micoletzky, 1922 (additional source)
Alaimus acutus Thorne, 1939 (basis of record)
Alaimus editorus Siddiqi & Husain, 1967 (basis of record)
Alaimus hamulus Siddiqi & Husain, 1967 (basis of record)
Alaimus meyli Andrássy, 1961 (basis of record)
Alaimus parvus Thorne, 1939 (basis of record)
Alaimus primitivus de Man, 1880 (basis of record)
Amphidelus Thorne, 1939 (additional source)
Amphidelus puccinelliae Lorenzen, 1966 accepted as Paramphidelus puccinelliae (Lorenzen, 1966) Coomans & Raski, 1988 (additional source)
Amphidelus stefanskii Juget, 1969 (basis of record)
Amphimonhystera Allgén, 1929 (additional source)
Amphimonhystera anechma (Southern, 1914) Lorenzen, 1977 (additional source)
Amphimonhystera helgolandica Riemann, 1967 accepted as Ammotheristus helgolandicus (Riemann, 1967) Lorenzen, 1977 (additional source)
Amphimonhystera paranechma Allgén, 1935 (additional source)
Amphimonhystera subtilis Lorenzen, 1972 accepted as Ammotheristus subtilis (Lorenzen, 1972) Lorenzen, 1977 (additional source)
Anaplectus granulosus (Bastian, 1865) De Coninck & Schuurmans Stekhoven, 1933 (basis of record)
Anonchinae (basis of record)
Anoplostoma Bütschli, 1874 (additional source)
Anoplostoma blanchardi de Man, 1888 accepted as Anoplostoma campbelli Allgén, 1932 (additional source)
Anoplostoma campbelli Allgén, 1932 (basis of record)
Anoplostoma elegans Kreis, 1929 (additional source)
Anoplostoma exceptum Schulz, 1935 (additional source)
Anoplostomatidae Gerlach & Riemann, 1974 (additional source)
Anoplostomatinae (additional source)
Anticoma Bastian, 1865 (additional source)
Anticoma acuminata (Eberth, 1863) Bastian, 1865 (additional source)
Anticoma arctica Steiner, 1916 (additional source)
Anticoma brevicaudata Kreis, 1963 (additional source)
Anticoma brevisetosa Platonova, 1967 (additional source)
Anticoma eberthi Bastian, 1865 (additional source)
Anticoma ecotronis Boucher, 1977 (basis of record)
Anticoma insulaealbae Filipjev, 1927 (additional source)
Anticoma longicaudata Kreis, 1928 (additional source)
Anticoma minor Filipjev, 1927 (additional source)
Anticoma pellucida Bastian, 1865 accepted as Anticoma limalis novozemelica Filipjev, 1927 accepted as Anticoma acuminata (Eberth, 1863) Bastian, 1865 (additional source)
Anticoma stekhoveni Wieser, 1953 accepted as Anticoma wieseri Mawson, 1958 (additional source)
Anticoma strandi Allgén, 1940 (additional source)
Anticoma wieseri Mawson, 1958 (basis of record)
Anticomidae Filipjev, 1918 (additional source)
Anticomopsis Micoletzky & Kreis, 1930 (additional source)
Anticomopsis typica Micoletzky, 1930 (additional source)
Anticyathus Cobb, 1920 (additional source)
Anticyclus Cobb, 1920 (additional source)
Anticyclus exilis Cobb, 1920 (additional source)
Anticyclus gigas Vitiello, 1969 (additional source)
Antomicron Cobb, 1920 (additional source)
Antomicron elegans (de Man, 1922) De Coninck, 1965 (additional source)
Antomicron pellucidum Cobb, 1920 (additional source)
Antomicron pratense Lorenzen, 1966 (additional source)
Antomicron profundum Vitiello, 1971 (additional source)
Aphanolaimus aquaticus von Daday, 1894 (basis of record)
Aphanolaimus attentus de Man, 1880 (basis of record)
Aphelenchoidea Fuchs, 1937 (basis of record)
Aponchiidae Gerlach, 1963 (additional source)
Aponchium cylindricolle Cobb, 1920 (basis of record)
Aponema Jensen, 1978 (additional source)
Aponema torosus (Lorenzen, 1973) Jensen, 1978 accepted as Aponema torosum (Lorenzen, 1973) Jensen, 1978 (basis of record)
Araeolaimus de Man, 1888 (additional source)
Araeolaimus bioculatus (de Man, 1876) de Man, 1988 (additional source)
Araeolaimus demani (Schuurmans Stekhoven, 1950) Wieser, 1956 (additional source)
Araeolaimus elegans de Man, 1888 (additional source)
Araeolaimus filipjevi Schuurmans Stekhoven & Adam, 1931 (additional source)
Araeolaimus gajevskii Paramonov, 1929 (additional source)
Araeolaimus longicauda Allgén, 1929 (additional source)
Araeolaimus longisetosus Wieser, 1954 (additional source)
Araeolaimus macrocirculus Kreis, 1928 (additional source)
Araeolaimus mediterraneus (de Man, 1876) de Man, 1888 (additional source)
Araeolaimus microphthalmus (de Man, 1893) Filipjev, 1918 accepted as Araeolaimoides microphthalmus de Man, 1893 (additional source)