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 Betaproteobacteria Garrity et al. 2006
         Order Nitrosomonadales Garrity et al. 2006
           Family Spirillaceae Migula 1894 (Approved Lists 1980) [monotypic]
             1 Genus Spirillum Ehrenberg 1832 (Approved Lists 1980)