Trinomial nomenclature
In biology, trinomial nomenclature refers to names for taxa below the rank of species. This is different for animals and plants:
  • for animals see trinomen
    In zoological nomenclature, a trinomen , or trinominal name, refers to the name of a subspecies.A trinomen is a name consisting of three names: generic name, specific name and subspecific name. The first two parts alone form the binomen or species name. All three names are typeset in italics, and...

    . There is only one rank allowed below the rank of species: subspecies.
  • for plants see infraspecific name (botany)
    Infraspecific name (botany)
    In botany, an infraspecific name is the name for any taxon below the rank of species, i.e. an infraspecific taxon. The scientific names of plants are regulated by the International Code of Botanical Nomenclature...

    . There is an indeterminate number of infraspecific ranks allowed below the level of species: subspecies is the highest ranked of these.
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