ICSPInternational Committee on Systematics of Prokaryotes

The Role of the ICSP (International Committee on Systematics of Prokaryotes) in the Nomenclature and Taxonomy of Prokaryotes

Hans G. Trüper, Chairman of the Judicial Commission of the ICSP

Brian J. Tindall, Vice-chairman of the Judicial Commission of the ICSP


The ICSP is an international committee within the International Union of Microbiological Societies (IUMS) which is responsible for matters relating to prokaryote nomenclature and taxonomy.

The ICSP consists of an executive board, the members of the Judicial Commission and members elected from member societies of the IUMS. In addition, the ICSP has a number of subcommittees which deal with matters relating to the nomenclature and taxonomy of specific groups of prokaryotes. The ICSP is also responsible for overseeing the publication of the International Code of Nomenclature of Bacteria (the Bacteriological Code) and the International Journal of Systematic and Evolutionary Microbiology (IJSEM) (formerly the International Journal of Systematic Bacteriology, IJSB). IUMS has now agreed to transfer copyright of future versions of the International Code of Nomenclature of Bacteria (to be renamed the International Code of Nomenclature of Prokaryotes) to the ICSP.

During the 1960s, the Judicial Commission recognized the need to deal with a problem which continues to affect other Codes of Nomenclature, the problem of knowing how to apply all published names of taxa. The solution which was sought involved the review of as many published names as possible, with respect to forgotten (old) and useless names. Although botany and zoology have examined ways of solving this problem by the use of 'Names in Current Usage' (botany) or introducing a rule by which names not used for 50 years need no longer be taken into consideration (zoology), none of these solutions have been totally satisfactory (or abandoned). The solution in prokaryote nomenclature was to introduce a list of protected names (the Approved Lists of Bacterial Names) together with an official system of registration/indexing of new names and combinations. The Bacteriological Code was altered in order to conform to this new way of working. The publication of the Approved Lists in January 1980 included those names which had been identified by appropriate types and circumscriptions. Names which were not included on this list were considered to no longer have standing in nomenclature. In addition, only names which were published in accordance with the Bacteriological Code (officially registered/indexed) could be considered to have standing in bacterial nomenclature. Technically, such names are 'validly published', but there may be confusion with the same term under the International Code of Botanical Nomenclature (ICBN), where it does not (currently) involve compulsory registration/indexing.

In order for the current system to work, all new names and combinations validly published appear in the IJSEM. This journal is the official journal of the ICSP and ensures that the system of valid publication of a name or a new combination is also overseen by the ICSP. Valid publication of a new name or a new combination may be either via an original publication in the IJSEM or by notification of the fact that effective publication of the name or new combination has appeared in another journal, via the 'Validation Lists'. In continuing its policy of innovation, members of the ICSP have also seen the need to provide a central list of changes of taxonomic opinion which have not resulted in the creation of new names or new combinations. Both these lists and the 'Validation Lists' are the responsibility of the Lists Editor, who is currently Dr Jean P. Euzéby.

Within the ICSP, the Judicial Commission is responsible for ruling on any problems which arise in the nomenclature of prokaryotes, and the editorial board of the Bacteriological Code is responsible for overseeing and publishing changes to the published version of the Code.

The ICSP (including the Judicial Commission and the Lists Editor) is responsible for the working of the current Bacteriological Code and its system of registering/indexing names. Consequently, this body is the sole 'authority' for governing on the implementation of the Bacteriological Code and determining which names are validly published (or may be validly published). Some confusion has arisen in the past (and continues to be perpetuated at present) by drawing up lists of names which either have not taken the Bacteriological Code into consideration, or have resulted from incorrect interpretation of the Code. It is important that any future work involving the drawing on of lists of names of prokaryotes involves those people who are familiar with those lists and their contents, together with the workings of the Bacteriological Code. This should avoid misunderstandings, or misinterpretations relating to the content and purpose of lists of validly published prokaryotic names, as well as using them as a basis for lists which may be developed, based on the application of the taxonomic opinion of appropriate authorities in this field.

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