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 Desulfurococcales Huber and Stetter 2002
                       Family Desulfurococcaceaeᵀ Zillig and Stetter 1983
                         Genus Ignicoccus Huber et al. 2000
                           1 Ignicoccus hospitalis Paper et al. 2007
                           2 Ignicoccus islandicusᵀ Huber et al. 2000
                           3 Ignicoccus pacificus Huber and Stetter 2000