Kingdom Fungi R.T.Moore (1980) - fungi
   Phylum Chytridiomycota Doweld (2001)
     Class Chytridiomycetes Moebius (1929)
       Family Thalassochytriaceae Doweld (2014), incertae sedis [monotypic]
         Genus Thalassochytrium Nyvall, M. Pedersén & Longcore (1999) [monotypic]
           Thalassochytrium gracilariopsidisᵀ Nyvall, M. Pedersén & Longcore (1999)