Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         [crown] Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Clade neomura Cavalier-Smith, 1987
             Domain Archaea Woese et al. 1990 [paraphyletic]
               Superphylum TACK Guy and Ettema 2011
                 Phylum Crenarchaeota Garrity and Holt 2001
                   Class Thermoprotei Reysenbach 2002
                     Order Sulfolobales Stetter 1989 [monotypic]
                       Family Sulfolobaceaeᵀ Stetter 1989
                         Genus Acidianus Segerer et al. 1986
                           1 Acidianus ambivalens (Zillig and Böck 1987) Fuchs et al. 1996
                           2 Acidianus brierleyi (Zillig et al. 1980) Segerer et al. 1986
                           3 Acidianus infernusᵀ Segerer et al. 1986
                           4 Acidianus sulfidivorans Plumb et al. 2007