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 Rickettsiales Gieszczykiewicz 1939 (Approved Lists 1980)
           1 Family Anaplasmataceae Philip 1957 (Approved Lists 1980)
           2 Family Holosporaceae Görtz and Schmidt 2006 [monotypic]
           3 Family Rickettsiaceae Pinkerton 1936 (Approved Lists 1980)
           4 Genus Lyticum (ex Preer et al. 1974) Preer and Preer 1982, incertae sedis
           5 Genus Pseudocaedibacter Quackenbush 1982, incertae sedis
           6 Genus Symbiotes Philip 1956 (Approved Lists 1980), incertae sedis
           7 Genus Tectibacter (ex Preer et al. 1974) Preer and Preer 1982, incertae sedis