[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 "Alicyclobacillaceae" da Costa & Rainey, 2010 see Family Alicyclobacillaceae da Costa and Rainey 2010
             Genus Alicyclobacillus Wisotzkey et al. 1992
               [Alicyclobacillus acidocaldarius] (Darland and Brock 1971) Wisotzkey et al. 1992
                 1 Alicyclobacillus acidocaldarius subsp. acidocaldariusᵀ (Darland and Brock 1971) Nicolaus et al. 2002
                 2 Alicyclobacillus acidocaldarius subsp. rittmannii Nicolaus et al. 2002