A robust taxonomy is essential for the organized study of prokaryotes and the effective communication of microbial knowledge. The genus rank is the mainstay of biological classification as it brings together under a common name a group of closely related organisms sharing the same recent ancestry and similar characteristics. Despite the unprecedented resolution afforded by whole-genome sequencing in defining evolutionary relationships, a consensus approach for phylogenomics-based prokaryotic genus delineation remains elusive. Taxonomists use different demarcation criteria, sometimes leading to genus rank over-splitting and the creation of multiple new genera. This work reports a simple, reliable, and standardizable method that seeks to minimize subjectivity in genomics-based demarcation of prokaryotic genera, exemplified through application to the order Mycobacteriales. Formal descriptions of proposed taxonomic changes based on our study are included.
Keywords: Corynebacteriineae; Mycobacteriales phylogenomics; Mycobacteriineae; Mycobacterium; Mycobacteroides; Prescottella; Rhodococcoides; Rhodococcoides fascians; Rhodococcus; Rhodococcus equi; genus demarcation; prokaryotic genus definition.