Strain SB0023/3( T), isolated from spores of the arbuscular mycorrhizal fungusGlomus iranicumvar.tenuihypharum, was analysed to determine whether it represents a new species. It was studied for its applicability in the field of agriculture to reduce the input of nitrogen fertilizers. Comparative analysis of the 16S rRNA gene sequence shows the strain to be affiliated to the genusMethylobacterium, the closest similarities (98.7%) being shared withMethylobacterium dankookense. Further phylogenomic analysis through Up-to-date Bacterial Core Gene (UBCG) confirmedMethylobacterium dankookenseas its closest relative. Average Nucleotide Identity (ANI) and in silico DNA-DNA hybridization (DDH) were lower than 92% and 44%, respectively, of the values shown by its phylogenetic relatives. Its genome had an approximate length of 6.05 Mb and the G + C content of the genome was 70.1 mol%. The main cellular fatty acid was Summed Feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c). It is a Gram-staining-negative, pink-pigmented, strictly aerobic and facultative methylotroph; it grows at 28 oC and can grow at up to 3% salinity in the presence of sodium chloride. All the data collected support the naming of a novel species to accommodate the strain SB0023/3( T), for which the nameMethylobacterium symbioticumsp. nov. is proposed. The type strain is SB0023/3( T)(=CECT 9862( T) =PYCC 8351( T)).