Mycoplasma haemomuris
is causative of infectious anaemia or splenomegaly in rodents. We examined the nucleotide sequences of the non-ribosomal genes, rnpB and dnaK, in strains of the species
M. haemomuris
detected in small field mice and black rats. rnpB nucleotide sequences in strains of the species
M. haemomuris
isolated from small field mice and black rats had only 89 % sequence similarity, suggesting their separation into two distinct subgroups. dnaK had a nucleotide sequence similarity of 84 % between the subgroups. These results support the classification of
M. haemomuris
into two genetically distinct subgroups. Here we propose the establishment of these subgroups as ‘Candidatus Mycoplasma haemomuris subsp. musculi’, detected in small field mice (Apodemus argenteus), and ‘Candidatus Mycoplasma haemomuris subsp. ratti’, detected in black rats (Rattus rattus).