Kingdom Protoctista Hogg, 1860
   Phylum Oomycota Arx (1967)
     1 Subclass Saprolegniomycetidae Dick et al. (1984) see Class Oomycetes G.Winter (1880)
     2 Subclass Peronosporomycetidae M.W. Dick (1984) see Subclass Peronosporomycetidae M.W. Dick (2001)