Phylogenomics and comparative genomic analyses support the creation of the novel family Ignatzschineriaceae fam. nov. comprising the genera Ignatzschineria and Wohlfahrtiimonas within the order Cardiobacteriales.

The genera Ignatzschineria and Wohlfahrtiimonas were originally classified as members of the family Xanthomonadaceae, order Xanthomonadales of the class Gammaproteobacteria. With the recent taxonomic revisions in the order Xanthomonadales, the two genera were left unclassified in both family and order level. As members of these genera were considered emerging pathogens, their proper classification is therefore relevant. Here, a phylogenomics and comparative genomic approach was used to ascertain the taxonomic position of the two genera. Result showed that the members of the two genera formed a highly supported monophyletic clade with the members of the order Cardiobacteriales. This close affiliation was further supported by the results of the comparative analysis of the 16S rRNA sequence similarity values. The comparative analyses of the 16S rRNA sequence similarity and average amino acid identity values also implied that the two genera represent a single novel family. Conserved signature indels (CSIs) in seven protein sequences were exclusively shared by the members of the novel family. In addition, four CSIs were also found to be useful in delimiting members of the two genera at the genus level. To accommodate the two genera in a single family within the order Cardiobacteriales, the name Ignatzschineriaceae fam. nov. is proposed.