Position in a system
| system | Vitae - living organisms |
| domain | Eukaryota Whittaker & Margulis, 1978 - lifeforms with nucletic cells |
| superregnum | Bikonta - bikonts |
| Corticata | |
| kingdom | Chromalveolata Adl et al., 2005 |
| subregnum | Chromobionta Cavalier-Smith, 1991 |
| phylum | Peronosporomycota M. W. Dick, 1995 |
| class | Peronosporomycetes Locq., 1974 - water molds |
| subclass | Saprolegniomycetidae M. W. Dick, 2001 |
| order | Saprolegniales E. Fisch., 1892 |
| family | Leptolegniaceae M. W. Dick, 1999 |
| genus | Aphanomyces de Bary, 1860 |
| species | Aphanomyces astaci Schikora, 1906 - Crayfish Plague |