procaryotes
   Domain Bacteria Woese et al. 1990 stat. inval. see Domain Bacteria Woese et al. 2024
     Phylum Firmicutes (Gibbons and Murray 1978) Garrity and Holt 2001 stat. inval. see Phylum Bacillota Gibbons and Murray 2021
       Class "Clostridia" "Garrity and Holt 2001" nom. nud. see Class Clostridia Rainey 2010
         1 Order Clostridiales Prévot 1953 (Approved Lists 1980) see Order Eubacteriales Buchanan 1917 (Approved Lists 1980)
         2 Order "Thermoanaerobacteriales" "Garrity and Holt 2001" nom. nud. [monotypic] see Order Thermoanaerobacterales Wiegel 2009 nom. inval.
         3 Order Haloanaerobiales Rainey and Zhilina 1995 see Order Halanaerobiales corrig. Rainey and Zhilina 1995