Type species

[4] Whether or not currently recognized as valid, every named genus or subgenus in zoology is theoretically associated with a type species.

In practice, however, there is a backlog of untypified names defined in older publications when it was not required to specify a type.

A type species is both a concept and a practical system that is used in the classification and nomenclature (naming) of animals.

[6] The International Code of Zoological Nomenclature states that the original name (binomen) of the type species should always be cited.

However, the type species of Homarus should always be cited using its original name, i.e. Astacus marinus Fabricius, 1775, even though that is a junior synonym of Cancer grammarius Linnaeus, 1758.