There is no official classification of prokaryotes, but the names given to prokaryotes are regulated. The International Code of Nomenclature of Bacteria (Bacteriological Code) and its successors contain General Considerations, Principles, Rules and Recommendations which govern the way in which the names of prokaryotes are to be used. The last revision of the Code is the cornerstone of prokaryotic nomenclature.

In 1975, the Bacteriological Code (1975 Revision) introduced a new concept, that of the valid publication of names of prokaryotes. Since then nomenclature is regulated in prokaryote systematics by an official system of registering (or indexing) via a centralized system those names which may be used in prokaryote taxonomy. The "valid publication (of a name)" is the formal term for registering a name. The International Code of Nomenclature of Bacteria (1990 Revision) states that the name of a taxon is validly published, and therefore has standing in nomenclature, if its proposal is accompanied by a number of criteria.

The designation of a nomenclatural type is among these criteria. Much like physics, which has reference points for the meter or the kilogram, biology has the nomenclatural types as the reference points for a taxon. In the cases of the species and subspecies, these reference points are represented by type strains. Given their central importance, it is crucial that type strains be made available as widely as possible.

The publication of the Approved Lists of Bacterial Names in 1980 was part of the concept of valid publication, and set a new starting point in prokaryotic nomenclature. This system was unique to the International Code of Nomenclature of Bacteria (even though virology has followed this principle) and was introduced in 1980 to combat uncertainties in the usage of the c. 40,000 names that had accumulated over the previous c. 200 years. With the introduction of the Approved Lists of Bacterial Names, only 2,000+ names were accepted for transfer into the modern system.

The Bacteriological Code (1990 Revision) and its successors also state that only correct names are to be used, i.e. based on (1) valid publication, (2) legitimacy, and (3) priority of publication (Principle 6). This does not mean that there is an official classification of bacteria [1], even though there is an official nomenclature. It is indeed important to be aware that taxonomy is not regulated by the code although nomenclature is formally regulated, i.e. there are names validly published as a result of conformity with the Rules of Nomenclature. For instance, the code recognizes a "valid published species name", but the term "validly published species" has no meaning. It is nevertheless being frequently met with in some of the literature. Similarly, the frequently used term "validly described" is meaningless.

"Many microbiologists are not particularly interested in nomenclature and are unaware of or indifferent to the problem they sometimes create" [2]. However, nomenclature is a vital component of systematic bacteriology and it is neither esoteric nor absurd. The Bacteriological Code (1990 Revision) and its most recent successor, which is the cornerstone of prokaryotic nomenclature, are not always easy to use. In fact, the formal system of naming bacteria appears sometimes tiresome, confusing and even exasperating to the working bacteriologist [3]. Accordingly, some bacteriologists are not aware of the Rules.


  1. SNEATH (P.H.A.) and BRENNER (D.J.): "Official" nomenclature lists. ASM News, 1992, 58, 175.
  2. GIBBONS (N.E.): Reference collections of bacteria. - The need and requirements for type and neotype strains. In: R.E. BUCHANAN and N.E. GIBBONS (editors), Bergey’s Manual of Determinative Bacteriology, eighth edition, The Williams & Wilkins Company, Baltimore, 1974, p. 14-17.
  3. BOUSFIELD (I.J.): Bacterial nomenclature and its role in systematics. In: M. GOODFELLOW and A.G. O’DONNELL (editors), Handbook of new bacterial systematics, Academic Press, London, 1993, p. 317-338.

A variety of resources are provided which assist in reading and comprehending this "List of Prokaryotic Names with Standing in Nomenclature". Users of LPSN are advised to consult these resources in addition to those available at the website of the ICSP, the body that governs the International Code of Nomenclature of Prokaryotes. Information on nomenclature available at LPSN:

The notes on the pages for the individual taxon names also included many hints on nomenclatural topics. The taxon pages refer to LPSN glossary for clarifying a variety of issues; aspects of nomenclature are among them.

A special aspect of nomenclature is the correct formation of names according to the orthographical rules of Latin or Greek. Yet another page treats taxonomy and systematics.

A selection of publications on nomenclature (cited in chronological order, without Judicial Opinions and Requests for an Opinion and without publications focussing on the formation of names):

















The collections of internet links found in the previous versions of LPSN may not be continued as such but the content distributed over pages dedicated to specific topics. Please see the archived version.

Some of the ancient LPSN pages on nomenclature are not going to be moved to the new system. The contained information is either outdated or available via the general search page. The archived versions of these pages are found here:

This LPSN page was printed on 2023-01-29 12:56:53