prokaryotes - bacteria see Domain Bacteria Woese et al. 1990
   Domain "Bacteria" Woese et al. 1990
     Phylum "Proteobacteria" Garrity et al. 2005 see Superphylum Proteobacteria Craig et al. 2010
       Class Gammaproteobacteria Garrity et al. 2005
         Order Methylococcales Bowman 2005
           Family Crenotrichaceae Hansgirg 1888 (Approved Lists 1980) [monotypic]
             1 Genus Crenothrix Cohn 1870 (Approved Lists 1980)