Procaryotic Genera
   Domain "Bacteria" Woese et al. 1990 stat. inval. see Domain Bacteria Woese et al. 2024
     Phylum Proteobacteria Garrity and Holt 2001 nom. nud. see Phylum Proteobacteria Garrity et al. 2005 stat. inval.
       Class "Gammaproteobacteria" "Garrity and Holt 2001" nom. nud. see Class Gammaproteobacteria Garrity et al. 2005
         Order "Thiotrichales" "Garrity and Holt 2001" nom. nud. see Order Thiotrichales Garrity et al. 2005 nom. illeg.
           Family "Piscirickettsiaceae" "Garrity and Holt 2001" nom. nud. see Family Piscirickettsiaceae Fryer and Lannan 2005
             1 Genus Piscirickettsia Fryer et al. 1992
             2 Genus Cycloclasticus Dyksterhouse et al. 1995
             3 Genus Hydrogenovibrio Nishihara et al. 1991
             4 Genus Methylophaga Janvier et al. 1985
             5 Genus Thiomicrospira Kuenen and Veldkamp 1972 (Approved Lists 1980)