Type species
In taxonomy, a type species is a technical phrase, involved in the application (typification) of formal names (biological, binomial nomenclature). Very roughly speaking, it is the species that fixes (that is, permanently attaches) a genus to its formal name (its generic name).
In zoology
In zoological nomenclature this is regulated by article 42.3 of the International Code of Zoological Nomenclature; the type of the name of a genus or subgenus (a "genus-group name") is the "type species". In the Glossary, this is defined as
- "The nominal species that is the name-bearing type of a nominal genus or subgenus".
The species name in turn is fixed to a type specimen. Ideally, every named genus or subgenus should have a type species, but in practice there is a backlog of untypified names.
In botany
In botany "type species" is an informal phrase only. In botanical nomenclature, the type of a name, of a genus or otherwise, is a specimen (or illustration) (ICBN, articles 10.1, 8.1 and 10.4). In the case of the name of a genus (or of a subdivision of a genus) this type will usually be the type of an included species, and can be indicated by the name of this species (Art 10.1). This species is sometimes informally called the "type species", but this phrase has no formal standing in botany.