Infraspecific epithet

In botany, an infraspecific name is the scientific name for any taxon below the rank of species, i.e. an infraspecific taxon. (A "taxon", plural "taxa", is a group of organisms to be given a particular name.) The scientific names of botanical taxa are regulated by the International Code of Nomenclature for algae, fungi, and plants (ICN). This specifies a 'three part name' for infraspecific taxa, plus a 'connecting term' to indicate the rank of the name. An example of such a name is Astrophytum myriostigma subvar. glabrum, the name of a subvariety of the species Astrophytum myriostigma (bishop's hat cactus).

Names below the rank of species of cultivated kinds of plants and of animals are regulated by different codes of nomenclature and are formed somewhat differently.

Article 24 of the ICN describes how infraspecific names are constructed. The order of the three parts of an infraspecific name is:

It is customary to italicize all three parts of such a name, but not the connecting term. For example:

The recommended abbreviations for ranks below species are, for example:

Like specific epithets, infraspecific epithets cannot be used in isolation as names. Thus the name of a particular species of Acanthocalycium is Acanthocalycium klimpelianum, which can be abbreviated to A. klimpelianum where the context makes the genus clear. The species cannot be referred to as just klimpelianum. In the same way, the name of a particular variety of Acanthocalycium klimpelianum is Acanthocalycium klimpelianum var. macranthum, which can be abbreviated to A. k. var. macranthum where the context makes the species clear. The variety cannot be referred to as just macranthum.

Sometimes more than three parts will be given; strictly speaking, this is not a name, but a classification. The ICN gives the example of Saxifraga aizoon var. aizoon subvar. brevifolia f. multicaulis subf. surculosa; the name of the subform would be Saxifraga aizoon subf. surculosa.

For a proposed infraspecific name to be legitimate it must be in accordance with all the rules of the ICN. Only some of the main points are described here.

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