Inbotany, aninfraspecific name is thescientific name for anytaxon below therank ofspecies, i.e. aninfraspecific taxon orinfraspecies. The scientific names of botanical taxa are regulated by theInternational Code of Nomenclature for algae, fungi, and plants (ICN).[1] As specified by the ICN, the name of an infraspecific taxon is a combination of the name of a species and aninfraspecific epithet,[2] separated by a connecting term that denotes the rank of the taxon. An example of an infraspecific name isAstrophytum myriostigma subvar. glabrum, the name of a subvariety of the speciesAstrophytum myriostigma (bishop's hat cactus). In the previous example,glabrum is the infraspecific epithet.
Names below the rank of species of animals and of cultivated plants are regulated by different codes of nomenclature and are formed somewhat differently.
Article 24 of the ICN describes how infraspecific names are constructed.[2] 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.[3] For example:
The recommended abbreviations for ranks below species are:[4]
Although the connecting terms mentioned above are the recommended ones, the ICN allows for other connecting terms in validly published infraspecific taxa. It specifically mentions that Greek letters α, β, γ, etc. can be used in this way in the original document[5] and further ranks may be added without limit.[6] Names that use these connecting terms are now deprecated (though still legal), but they have an importance because they can bebasionyms of current species. The commonest cases use "β" and "b"; examples mentioned in the ICN areCynoglossum cheirifolium β Anchusa (lanata)[7] andPolyporus fomentarius βapplanatus[8] whilst other examples (coming from the fungus databaseIndex Fungorum) areAgaricus plexipes bfuliginaria[9] andPeziza capula ßcernua.[10] The ICN allows the possibility that avalidly published name could have no defined rank and uses "[unranked]" as the connecting term in such cases.[11]
Like specific epithets, infraspecific epithets cannot be used in isolation as names.[12] Thus the name of a particular species ofAcanthocalycium isAcanthocalycium klimpelianum, which can be abbreviated toA. klimpelianum where the context makes the genus clear. The species cannot be referred to as justklimpelianum. In the same way, the name of a particular variety ofAcanthocalycium klimpelianum isAcanthocalycium klimpelianum var.macranthum, which can be abbreviated toA. k. var.macranthum where the context makes the species clear. The variety cannot be referred to as justmacranthum.
Sometimes more than three parts will be given; strictly speaking, this is not a name, but aclassification. The ICN gives the example ofSaxifraga aizoon var.aizoon subvar.brevifolia f.multicaulis subf.surculosa; the name of the subform would beSaxifraga aizoon subf.surculosa.[13]
For a proposed infraspecific name to be legitimate it must be in accordance with all the rules of the ICN.[14] Only some of the main points are described here.
A key concept in botanical names is that of atype. In many cases the type will be a particular preserved specimen stored in aherbarium, although there are other kinds of type. Like other names, an infraspecific name is attached to a type. Whether a plant should be given a particular infraspecific name can then be decided by comparing it to the type.[15]
There is no requirement for a species to be divided into infraspecific taxa, of whatever rank; in other words, a species does not have to have subspecies, varieties, forms, etc. However, if infraspecific ranks are created, then the name of the type of the species must repeat the specific epithet as its infraspecific epithet. The type acquires this name automatically as soon as any infraspecific rank is created.[16] As an example, considerPoa secundaJ.Presl, whose type specimen is in the Wisconsin State Herbarium.[17]
The same epithet can be used again within a species, at whatever level, only if the names with the re-used epithet are attached to the same type.[16] Thus there can be a form calledPoa secunda f.juncifolia as well as the subspeciesPoa secunda subsp.juncifolia if, and only if, the type specimen ofPoa secunda f.juncifolia is the same as the type specimen ofPoa secunda subsp.juncifolia (in other words, if there is a single type specimen whose classification isPoa secunda subsp.juncifolia f.juncifolia).
If two infraspecific taxa which have different types are accidentally given the same epithet, then ahomonym has been created. The earliest published name is the legitimate one and the other must be changed.[18]
When indicating authors for infraspecific names, it is possible to show either just the author(s) of the final, infraspecific epithet, or the authors of both the specific and the infraspecific epithets, as is demonstrated throughout the ICN.[19] Examples:
Inzoological nomenclature, names of taxa below species rank are formed somewhat differently, using atrinomen or 'trinomial name'. No connecting term is required as there is only one rank below species, thesubspecies.
TheProkaryotic Code was split from the ICN in 1975. This nomenclature only governs one infraspecific rank, the subspecies, but allows a number ofinfrasubspecific subdivisions to be used. The authorship is to be specified in the form "Bacillus subtilis subsp.spizizenii Nakamuraet al. 1999.", i.e. with only the infraspecific author.[20]: Rules 13–4, Appendix 10
Authors may still choose to use ungoverned ranks such as sv. (serovar) and pv. (pathovar).
TheICN does not regulate the names of cultivated plants, ofcultivars, i.e. plants specifically created for use in agriculture or horticulture. Such names are regulated by theInternational Code of Nomenclature for Cultivated Plants (ICNCP).
Although logically below the rank of species (and hence "infraspecific"), acultivar name may be attached to any scientific name at the genus level or below. The minimum requirement is to specify a genus name.[21] For example,Achillea 'Cerise Queen' is a cultivar;Pinus nigra 'Arnold Sentinel' is a cultivar of the speciesP. nigra (which is propagated vegetatively, bycloning).