The International Committee on Systematics of Prokaryotes serves to administer the rules of prokaryotic nomenclature via the International Code of Nomenclature of Prokaryotes, ensures the publication of the International Journal of Systematic and Evolutionary Microbiology, and works to represent the interests of the microbiological disciplines regarding prokaryotic nomenclature. The functions and mechanisms of operation of the International Committee on Systematics of Prokaryotes (ICSP) are defined in its Statutes, which were last revised in 2019. As members of the 2020-2023 and the 2023-2026 ICSP Executive Board and the Judicial Commission, we propose here some further revisions to help improve the clarity and functionality of the Statutes.

Following a proposal to emend Appendix 9 of the International Code of Nomenclature of Prokaryotes with guidelines for the naming of genera after geographical locations, I here report the outcome of the ballot on this proposal by the members of the International Committee on Systematics of Prokaryotes and present the guidelines to be incorporated in Appendix 9.

In 2014, it was reported that the bacterial genus name Rhodococcus Zopf 1891 was illegitimate due to the priority of the cyanobacterial genus name Rhodococcus Hansgirg 1884. Since that time, the consequences of this conclusion have been largely ignored, whilst changes have been made to relevant Rules of the International Code of Nomenclature of Prokaryotes, including significant changes to the way in which the Code treats the names of members of Cyanobacteriota. Given the complexity of the nomenclatural issues, we request the opinion of the Judicial Commission of the International Committee on Systematics of Prokaryotes as to whether the genus name Rhodococcus Zopf 1891 (Approved Lists 1980) is illegitimate.

The International Code of Nomenclature of Prokaryotes (ICNP) now includes the categories domain and kingdom. For the purpose of the valid publication of their names under the ICNP, we consider here the two known domains, \'Bacteria\' and \'Archaea\', as well as a number of taxa suitable for the rank of kingdom, based on previous phylogenetic and taxonomic studies. It is proposed to subdivide the domain Bacteria into the kingdoms Bacillati, Fusobacteriati, Pseudomonadati and Thermotogati. This arrangement reflects contemporary phylogenetic hypotheses as well as previous taxonomic proposals based on cell wall structure, including \'diderms\' vs. \'monoderms\', Gracilicutes vs. Firmicutes, \'Negibacteria\' vs. \'Unibacteria\', \'Hydrobacteria\' vs. \'Terrabacteria\', and \'Hydrobacterida\' vs. \'Terrabacterida\'. The domain Archaea is proposed to include the kingdoms Methanobacteriati, Nanobdellati and Thermoproteati, reflecting the previous division into \'Euryarchaeota\', \'DPANN superphylum\' and \'TACK superphylum\'.

Following an electronic discussion on proposals to emend Principle 8, Rules 5b, 8, 15, 33a, and Appendix 7 of the International Code of Nomenclature of Prokaryotes (ICNP), I here report the outcome of the ballot on these proposals by the members of the International Committee on Systematics of Prokaryotes. These emendations enact the addition of the categories of kingdom and domain to the ICNP.

Following an electronic discussion on proposals to emend Rules 8, 15, 22, 25a, 30(3)(b), 30(4), 34a, and Appendix 7 of the International Code of Nomenclature of Prokaryotes, I here report the outcome of the ballot on these proposals by the members of the International Committee on Systematics of Prokaryotes.

Appendix 9, Section E of the International Code of Nomenclature of Prokaryotes provides guidelines on how to form adjectival specific and subspecific epithets that reflect the geographical location where the organism was found or studied. It does not mention ways of naming genera after geographical locations. We here propose emendation of Appendix 9 with the recommendations on how to form such names. Comments on the implementation of the current wording of Appendix 9, Section E are also made.

The nomenclature of prokaryotes is regulated by the rules of the International Code of Nomenclature of Prokaryotes (ICNP) and is based on the Linnaean binomial system. The current rules of the Code only cover the nomenclature of the cultivated minority. Proposals to incorporate the uncultivated majority of bacteria and archaea under the rules of the Code were recently rejected by the International Committee on Systematics of Prokaryotes. The provisional rank of Candidatus can be used to name uncultivated prokaryotes whose names cannot be validly published under the rules of the ICNP, but their names can now be validated under the Code of Nomenclature of Prokaryotes Described from Sequence Data (the SeqCode), which was recently established to cover the nomenclature of the uncultivated majority. Metagenomics, single-cell genomics, and high-throughput cultivation techniques have led to a flood of new organisms currently waiting to be named. Automated programs such as GAN and Protologger can assist researchers in naming and describing newly discovered prokaryotes, cultivated as well as uncultivated. However, Latin and Greek skills remain indispensable for proper quality control of names that must meet the standards set by the codes of nomenclature.

The validation of the name of a prokaryotic taxon under the International Code of Nomenclature of Prokaryotes (ICNP) is occasionally attempted although the original proposal of the name does not meet all requirements. The publication of a corrigendum is necessary in such a case but authors must ensure that the corrigendum contains the full description of the respective taxon. The modification of the original article is not compatible with the ICNP. One requirement for valid publication is that the effective publication of a taxon name constitutes a permanent record. Journals which modify articles after publication are not acceptable as a source of effective publications.

To complete the ongoing revision of the International Code of Nomenclature of Prokaryotes, we here propose emendation of Rules 8, 15, 22, 25a, 30(3)(b), 30(4), 34a and Appendix 7. These proposed emendations deal with: the nomenclatural type of taxa above genus; the suitability of names published in supplementary material or in papers published on e-print servers for effective publication; the number of culture collection designations to be included in an effective publication of a name of a species or subspecies to qualify for validation of the name; the kinds of restrictions that may be attached to deposits of type strains; and the question whether elevation of a subspecies to the rank of species or lowering of a species to the rank of subspecies establish new combinations. Some of these emendations change the meaning of the Code while others are mere textual clarifications.