 Prokaryotic nomenclature

Prokaryotic nomenclature is the system of rules used to attach scientific names to taxa of bacteria and archaea. Naming supplies stable references for scientific communication; deciding which organisms belong together remains a question of taxonomy and evidence. The 2025 revision of the International Code of Nomenclature of Prokaryotes explicitly preserves freedom of taxonomic thought.^[ref]

A nomenclatural type anchors a name to a reference element. A type strain serves this role for a named species under the ordinary species rules. The reference need not be the most typical member of its group: it fixes how the name is applied when the boundaries of a taxon are reconsidered.^[ref]

For an invented classification example, suppose a named species contains bacterial strains A, B and C, with A its type strain. New evidence divides the group into A+B and C. Anchoring the old name to A identifies which resulting group retains that reference; finding that C has an unusual metabolism does not itself move the name to C. The example separates a reproducible naming decision from the biological evidence for splitting the group.

A species name combines a genus name with a specific epithet. Valid publication and the use of a correct name involve further rules, including publication and priority requirements. A name appearing somewhere in print is therefore not automatically a name with standing under this Code.^[ref]