basionyms

A basionym is a formal term in biological nomenclature referring to the original name given to a taxon that is retained as the basis for a new name when the taxon is moved to a different genus or rank. The basionym’s epithet is typically retained in the new combination, and the authorship of the basionym is cited in the full citation of the new name. The concept is most prominently used in botanical nomenclature under the International Code of Nomenclature for algae, fungi, and plants (ICN).

Under the ICN, if a species is transferred to a different genus, the resulting name is a new combination. The basionym provides priority for the epithet, and the new combination preserves that epithet while indicating its origin by citing the basionym’s author in parentheses in the formal citation. If the basionym is illegitimate or preoccupied, the taxon may require a new epithet or other adjustments according to the code.

Example: a plant previously named Aster novae-angliae was moved to the genus Symphyotrichum, becoming Symphyotrichum novae-angliae. Here, Aster novae-angliae is the basionym; the new name retains the epithet, and the full citation shows the basionym author in parentheses.

Notes: While basionyms are a central concept in botany, the underlying idea—an original name serving as the basis for a renamed taxon—appears in other groups as well, though different terminology may be used. Understanding basionyms helps trace taxonomic history, preserve priority, and annotate revised classifications.