Procaryotic Genera
   Domain "Bacteria" Woese et al. 1990
     Phylum Proteobacteria Garrity and Holt 2001 see Phylum Proteobacteria Garrity et al. 2005
       Class "Gammaproteobacteria" nom. inval. see Class Gammaproteobacteria Garrity et al. 2005
         Order "Methylococcales" nom. inval. [monotypic] see Order Methylococcales Bowman 2005
           Family Methylococcaceae Whittenbury and Krieg 1984
             1 Genus Methylococcus Foster and Davis 1966 (Approved Lists 1980)
             2 Genus Methylobacter Bowman et al. 1993
             3 Genus Methylocaldum Bodrossy et al. 1998
             4 Genus Methylomicrobium Bowman et al. 1995
             5 Genus Methylomonas (ex Leadbetter 1974) Whittenbury and Krieg 1984
             6 Genus Methylosphaera Bowman et al. 1998