Position in a system
| system | Vitae - living organisms |
| domain | Eukaryota Whittaker & Margulis, 1978 - lifeforms with nucletic cells |
| superregnum | Unikonta |
| system | Opisthokonta Cavalier-Smith, 1987 |
| kingdom | Animalia Linnaeus, 1758 - animals |
| subregnum | Eumetazoa Butschli, 1910 |
| divisio | Bilateria Hatschek, 1888 - bilaterians |
| subdivisio | Protostomia Grobben, 1908 - protostomes |
| phylum | Nematoda Rudolphi, 1808 - nematodes |
| class | Adenophorea von Linstow, 1905 |
| subclass | Enoplia Pearse, 1942 |
| order | Enoplida Filipjev, 1929 |
| suborder | Ironina Siddiqi, 1983 |
| superfamily | Ironoidea de Man, 1876 |
| family | Ironidae de Man, 1876 |
| subfamily | Criptonchinae Chitwood, 1937 |
| genus | Criptonchus Cobb, 1913 |
| species | Criptonchus tristis (Ditlevsen, 1911) |