Phylogenomic analysis of the understudied Neisseriaceae species reveals a poly- and paraphyletic Kingella genus

Taxonomic classification and phylogenetic analysis of the Neisseriaceae family have focused on the pathogens Neisseria meningitidis and Neisseria gonorrhoeae. Less is known about the relationships of commensal Neisseria species and other Neisseriaceae genera, raising the possibility that the phylogeny of this family may not agree with current taxonomy. In this study, we used available nucleotide sequences and a phylogenetic approach to assess the Kingella genus and its relatives. We found that this genus is both paraphyletic and polyphyletic. Kingella potus is more closely related to Neisseria bacilliformis than to other Kingella species. The Alysiella and Simonsiella genera form a distinct clade within the Kingella genus that is closely related to the pathogens K. kingae and K. negevensis. We find a phylogenetic relationship between Conchiformibius, Alysiella, Simonsiella, and Kingella, which we name the CASK clade. Finally, we define the gene sets that differentiate each genus of the CASK clade from one another and from the rest of the Neisseriaceae family.