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 "Methanomicrobia" Garrity et al. 2005 nom. inval.
                     Order Methanomicrobialesᵀ Balch and Wolfe 1981
                       Family Methanospirillaceae Boone et al. 2002
                         Genus Methanospirillumᵀ Ferry et al. 1974 (Approved Lists 1980)
                           Methanospirillum hungateiᵀ corrig. Ferry et al. 1974 (Approved Lists 1980)