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. see Order Methylococcales Bowman 2005 Family Methylococcaceae Whittenbury and Krieg 1984 Genus Methylobacter Bowman et al. 1993 Genus Methylocaldum Bodrossy et al. 1998 Genus Methylomicrobium Bowman et al. 1995 Genus Methylomonas (ex Leadbetter 1974) Whittenbury and Krieg 1984 Genus Methylosphaera Bowman et al. 1998 1 Genus Methylococcus Foster and Davis 1966 (Approved Lists 1980)