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 Alphaproteobacteria Garrity et al. 2006
         Order Caulobacterales Henrici and Johnson 1935 (Approved Lists 1980)
           1 Family Caulobacteraceae Henrici and Johnson 1935 (Approved Lists 1980)
           2 Family Hyphomonadaceae Lee et al. 2005