Göker, Markus

The naming of prokaryotes is governed by the International Code of Nomenclature of Prokaryotes (ICNP) and partially by the International Code of Nomenclature for Algae, Fungi and Plants (ICN). Such codes must be able to determine names of taxa in a universal and unambiguous manner, thus serving as a common language across different fields and activities. This unity is undermined when a new code of nomenclature emerges that overlaps in scope with an established, time-tested code and uses the same format of names but assigns different nomenclatural status values to the names. The resulting nomenclatural confusion is not beneficial to the wider scientific community. Such ambiguity is expected to result from the establishment of the ‘Code of Nomenclature of Prokaryotes Described from DNA Sequence Data’ (‘SeqCode’), which is in general and specific conflict with the ICNP and the ICN. Shortcomings in the interpretation of the ICNP may have exacerbated the incompatibility between the codes. It is reiterated as to why proposals to accept sequences as nomenclatural types of species and subspecies with validly published names, now implemented in the SeqCode, have not been implemented by the International Committee on Systematics of Prokaryotes (ICSP), which oversees the ICNP. The absence of certain regulations from the ICNP for the naming of as yet uncultivated prokaryotes is an acceptable scientific argument, although it does not justify the establishment of a separate code. Moreover, the proposals rejected by the ICSP are unnecessary to adequately regulate the naming of uncultivated prokaryotes. To provide a better service to the wider scientific community, an alternative proposal to emend the ICNP is presented, which would result in Candidatus names being regulated analogously to validly published names. This proposal is fully consistent with previous ICSP decisions, preserves the essential unity of nomenclature and avoids the expected nomenclatural confusion.

The International Code of Nomenclature of Prokaryotes (ICNP) recently underwent some major modifications regarding the higher taxonomic ranks. On the one hand, the phylum category was introduced into the ICNP, which rapidly led to the valid publication of more than forty names of phyla. On the other hand, a decision on the retroactivity of Rule 8 regarding the names of classes was made, which removed most of the nomenclatural uncertainty that had affected those names during the last decade. However, it turned out that a number of names at the ranks of class, order and family are either not validly published or are validly published but illegitimate, although these names occur in the literature and are based on the type genus of a phylum with a validly published name. A closer examination of the literature for these and similar cases indicates that the names are unavailable under the ICNP either because of minor formal errors in the original descriptions, because another name should have been adopted for the taxon when the name was proposed, because of taxonomic uncertainties that were settled in the meantime, or because the names were placed on the list of rejected names. The purpose of this article is to fill the gaps by providing the missing formal descriptions and to ensure that the resulting taxon names are attributed to the original authors who did the taxonomic work.