Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Clade neomura Cavalier-Smith, 1987
             Domain Archaea Woese et al. 2024 [paraphyletic]
               Kingdom Methanobacteriati (Garrity and Holt 2023) Oren and Göker 2024
                 Phylum Methanobacteriotaᵀ Garrity and Holt 2023
                   Class Thermoplasmata Reysenbach 2002
                     Order Thermoplasmatalesᵀ Reysenbach 2002
                       Family Picrophilaceae Schleper et al. 1996 [monotypic]
                         Genus Picrophilusᵀ Schleper et al. 1996
                           1 Picrophilus oshimae Schleper et al. 1996
                           2 Picrophilus torridus Zillig et al. 1996