[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 "Bacilli" Garrity et al. 2001 nom. ined. see Class Bacilli Ludwig et al. 2010
         Order Bacillales Prévot 1953 (Approved Lists 1980)
           Family Bacillaceae Fischer 1895 (Approved Lists 1980)
             Genus Geobacillus Nazina et al. 2001
               01 Geobacillus stearothermophilus (Donk 1920) Nazina et al. 2001
               02 Geobacillus caldoxylosilyticus (Ahmad et al. 2000) Fortina et al. 2001
               03 Geobacillus debilis Banat et al. 2004 see Caldibacillus debilis (Banat et al. 2004) Coorevits et al. 2012
               04 Geobacillus gargensis Nazina et al. 2004
               05 Geobacillus jurassicus Nazina et al. 2005
               06 Geobacillus kaustophilus (Priest et al. 1989) Nazina et al. 2001
               07 Geobacillus lituanicus Kuisiene et al. 2004
               08 Geobacillus pallidus (Scholz et al. 1988) Banat et al. 2004 see Aeribacillus pallidus (Scholz et al. 1988) Miñana-Galbis et al. 2010
               09 Geobacillus subterraneus Nazina et al. 2001
               10 Geobacillus tepidamans Schäffer et al. 2004 see Anoxybacillus tepidamans (Schäffer et al. 2004) Coorevits et al. 2012
               11 Geobacillus thermocatenulatus (Golovacheva et al. 1991) Nazina et al. 2001
               12 Geobacillus thermodenitrificans (Manachini et al. 2000) Nazina et al. 2001
               13 Geobacillus thermoglucosidasius (Suzuki et al. 1984) Nazina et al. 2001
               14 Geobacillus thermoleovorans (Zarilla and Perry 1988) Nazina et al. 2001
               15 Geobacillus toebii Sung et al. 2002
               16 Geobacillus uzenensis Nazina et al. 2001
               17 Geobacillus vulcani (Caccamo et al. 2000) Nazina et al. 2004