Genome analysis-based union of the genus with the genus .

Early characterization of strains designated into the genera and was based upon biological and chemical characteristics. With the advent of 16S rRNA gene sequence analysis as an added taxonomic character, it became clear that the two genera did not form distinct and separate monophyletic clusters. A genome-level analysis of all 17 validly published species within the family has recently been performed. Phylogenetic analyses, comparisons of gene content, and the lack of genus-specific genes supported that species from the two genera are intermixed and should not be taxonomically separated. This level of analysis clearly reveals the necessity to revise the taxonomy of this family by merging the two genera into one, . Additionally, it was definitively determined that the strain originally designated as resides in this cluster and should be formally renamed as . Merging and yields a paraphyletic genus, but is supported by cell morphology and ecology to be distinguished from the genera and .