Phylogenomic evidence supporting the reclassification of Cedecea sulfonylureivorans within the genus Dryocola with subdivision into Dryocola clanedunensis subsp. clanedunensis comb. nov. and Dryocola clanedunensis subsp. sulfonylureivorans comb. nov.

Abstract

The bacterial order Enterobacterales has recently undergone major taxonomic revisions, with several new families and genera described. Within this framework, the rare genus Cedecea and the newly proposed genus Dryocola occupy closely related positions. The present study provides a comprehensive phylogenomic, phenotypic and functional assessment of Cedecea sulfonylureivorans LAM2020 T and Dryocola clanedunensis H11S18 T to clarify their taxonomic relationship. Genomic relatedness indices revealed high similarity between the two type strains, with average nucleotide identity, average amino acid identity and digital DNA–DNA hybridization values exceeding established species delineation thresholds. Phylogenetic analyses based on 16S rRNA, whole genomes and core gene sets consistently placed the two strains in a robustly supported monophyletic clade. These findings were further supported by shared metabolic and phenotypic traits. Taken together, the evidence demonstrates that C. sulfonylureivorans and D. clanedunensis represent members of the same biological species. Accordingly, and in line with Rule 42 of the International Code of Nomenclature of Prokaryotes, we propose the reclassification of C. sulfonylureivorans Li et al. 2024 as a later heterotypic synonym of D. clanedunensis Maddock et al. 2023. Furthermore, we propose two subspecies within this species: D. clanedunensis subsp. clanedunensis comb. nov. and D. clanedunensis subsp. sulfonylureivorans comb. nov.