[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   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
         Order Clostridiales Prévot 1953 (Approved Lists 1980) see Order Eubacteriales Buchanan 1917 (Approved Lists 1980)
           Family "Peptostreptococcaceae" "Garrity and Holt 2001" nom. nud. see Family Peptostreptococcaceae Ezaki 2010
             Genus Peptostreptococcus Kluyver and van Niel 1936 (Approved Lists 1980)
               1 Peptostreptococcus anaerobius (Natvig 1905) Kluyver and van Niel 1936 (Approved Lists 1980)
               2 Peptostreptococcus stomatis Downes and Wade 2006