Evaluation I found major concerns along this manuscript, and suggest a substantial revision.
Taxonomists have traditionally circumscribed the high taxa (specially orders and classes) with great subjectivity, i.e., without well accepted criteria. In terms of phylogenetic trees one premise has always been clear, a taxon must be monophyletic. This principle has been used in the present work to reconsider the status of some high taxa. However, authors do not explain objective criteria to properly interpret the rank of the clades, which impedes making a profound evaluation of the archaeal classification. Therefore, although authors have strong tools and dataset, they just achieved a small revision of the high taxa which is, indeed, quite biased by the underlying 16S guidelines.