Basionym

A basionym is a term in botanical nomenclature that refers to the original name given to a taxon, which serves as the basis for a later name when the taxon is reclassified. It comes from Greek, meaning the “basis name.” The basionym must be validly published under the rules of the International Code of Nomenclature for algae, fungi, and plants (ICN).

When a taxon is moved to a different genus or rank, the new name is called a recombination or new combination, and the basionym remains the reference point for the epithet and for priority. In the citation of the new combination, the author who established the new combination follows the basionym author in parentheses, for example: NewGenus species (BasionymAuthor) NewAuthor.

A name can serve as a basionym only if it is legitimate; if the original name is illegitimate or later deemed superfluous, it cannot function as a basionym, and the nomenclatural situation may require a different treatment. The basionym is not necessarily the currently accepted name, but it preserves the historical basis and priority of the epithet.

Examples are typically stated with placeholders, such as a species originally described as GenusA speciesname by Author1 that is later transferred to GenusB by Author2, yielding GenusB speciesname (Author1) Author2. In this case, GenusA speciesname is the basionym, cited to reflect its priority and historical basis for the new combination.

See also: taxonomic nomenclature; recombination; synonym; ICN.