[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain "Archaea" Woese et al. 1990 stat. inval. see Domain Archaea Woese et al. 2024
     Phylum "Euryarchaeota" Garrity and Holt 2002 stat. inval. see Kingdom Methanobacteriati (Garrity and Holt 2023) Oren and Göker 2024
       Class Methanococci Boone 2002
         Order Methanococcales Balch and Wolfe 1981
           Family Methanocaldococcaceae Whitman et al. 2002
             Genus Methanocaldococcus Whitman 2002
               Methanocaldococcus vulcanius (Jeanthon et al. 1999) Whitman 2002