Genome-based phylogeny of the genera Proteus and Cosenzaea and description of Proteus terrae subsp. terrae subsp. nov. and Proteus terrae subsp. cibarius subsp. nov.

The genera Proteus and Cosenzaea are closely related members of the family Morganellaceae . The genus Cosenzaea consists of the species Cosenzaea myxofaciens originally separated from the genus Proteus by rpoB gene analysis. Due to the high similarity of the 16S rRNA genes between species of both genera, the taxonomic status is here re-evaluated by a genome-based approach. Based on a core genome phylogeny and genome relatedness indices, it is shown that the taxonomy and nomenclature given for the basonym Proteus myxofaciens is more appropriate. Therefore, we propose to use this name in preference. Furthermore, the species status of Proteus terrae and Proteus cibarius was reassessed. Both species are related at subspecies level by digital DNA–DNA hybridization (dDDH) analysis. Additionally, average amino acid identity (AAI) and average nucleotide identity (ANI) do not support a separate species status, and therefore it is proposed to classify P. cibarius as a subspecies of P. terrae . Consequently, both species are being renamed Proteus terrae subsp. cibarius subsp. nov. and Proteus terrae subsp. terrae subsp. nov., respectively. The genome relatedness indices revealed a close relationship of the Proteus genomospecies 5 with P. terrae subsp. terrae . Thus, it has been assigned to the same subspecies.