methylocystis methylocystis methylocystis is a genus of bacteria from the family methylocystaceae. methylocystis scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: hyphomicrobiales family: methylocystaceae genus: methylocystis(ex whittenbury et al. 1970) bowman et al. 1993 type species m. parvus species m. bryophila belova et al. 2013 m. echinoides (ex gal'chenko et al. 1977) bowman et al. 1993 m. heyeri dedysh et al. 2007 m. hirsuta lindner et al. 2007 m. parvus (ex whittenbury et al. 1970) bowman et al. 1993 m. rosea wartiainen et al. 2006