Domain Bacteria Woese et al. 1990
   Phylum Proteobacteria Garrity and Holt 2001 see Phylum Proteobacteria Garrity et al. 2005
     Class "Betaproteobacteria" Garrity et al. 2001 nom. ined. see Class Betaproteobacteria Garrity et al. 2006
       Order "Nitrosomonadales" see Order Nitrosomonadales Garrity et al. 2006
         1 Family "Nitrosomonadaceae" see Family Nitrosomonadaceae Garrity et al. 2006
         2 Family Spirillaceae Migula 1894 (Approved Lists 1980)
         3 Family Gallionellaceae Henrici and Johnson 1935 (Approved Lists 1980)