In zoological nomenclature, a binomen (plural: binomina), is the two-part name of a species. The term was introduced in 1953, abolishing the previously used "binomial name" (as being inaccurate). A binomen consists of a generic name (for the genus) and a specific epithet (for the species). [1]
Both the generic and specific names are typeset in italics, but only the generic name is capitalised, for example, Canis lupus. If the generic name has already been mentioned in the same paragraph, it is often abbreviated to the initial letter in subsequent uses, for example, C. lupus.
In a taxonomic publication, the first mention of a binomen is often accompanied by the name of the author and the date, and sometimes publication details. This not only indicates who published the name, and the date of the publication, but is essential to determine priority.
Binomina are part of binominal nomenclature (as it is formally known in zoology) or binomial nomenclature (as it is known in botany). Binomina may be said to be a particular form of binomial names. Zoological nomenclature is governed by the International Code of Zoological Nomenclature. Other codes of nomenclature, which also use binomial nomenclature, apply to other types of organisms.
A trinomen is the three-part name of a subspecies.