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)
           Family Holosporaceae Görtz and Schmidt 2006 [monotypic]
             Genus Holospora (ex Hafkine 1890) Gromov and Ossipov 1981