[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain Bacteria Woese et al. 1990
     Phylum Firmicutes corrig. Gibbons and Murray 1978 (Approved Lists 1980)
       Class "Clostridia" Garrity et al. 2001 nom. ined. see Class Clostridia Rainey 2010
         Order "Thermoanaerobacteriales" see Order Thermoanaerobacterales Wiegel, 2010
           Family "Thermoanaerobacteriaceae" see Family Thermoanaerobacteraceae Wiegel, 2010
             Genus Caldanaerobacter Fardeau et al. 2004
               [Caldanaerobacter subterraneus] (Fardeau et al. 2000) Fardeau et al. 2004
                 1 Caldanaerobacter subterraneus subsp. subterraneusᵀ (Fardeau et al. 2000) Fardeau et al. 2004
                 2 Caldanaerobacter subterraneus subsp. yonseiensis (Kim et al. 2001) Fardeau et al. 2004
                 n.1 Caldanaerobacter subterraneus subsp. pacificus (Sokolova et al. 2001) Fardeau et al. 2004 see Carboxydibrachium pacificum corrig. Sokolova et al. 2001
                 n.2 Caldanaerobacter subterraneus subsp. tengcongensis (Xue et al. 2001) Fardeau et al. 2004