[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain Bacteria Woese et al. 1990 stat. inval. see Domain Bacteria Woese et al. 2024
     Phylum "Proteobacteria" Garrity et al. 2005 stat. inval. see Phylum Pseudomonadota Garrity et al. 2021
       Class Gammaproteobacteria Garrity et al. 2005
         Order Methylococcales Bowman 2005
           Family Methylococcaceae Whittenbury and Krieg 1984
             Genus Methylocaldum Bodrossy et al. 1998
               1 Methylocaldum szegediense Bodrossy et al. 1998
               2 Methylocaldum gracile (ex Romanovskaya et al. 1978) Bodrossy et al. 1998
               3 Methylocaldum tepidum Bodrossy et al. 1998