Usualis

Usualis is a Latin adjective used in biological nomenclature. In taxonomy, it means “usual” or “typical” and is used as a species epithet within a genus to indicate a form considered representative or common within that group. Like other epithets, usualis must agree in gender with the genus name; the neuter form for neuter genera is usuale.

The term is derived from Latin, formed with the adjectival suffix -alis meaning “pertaining to” and the base sense of “usual” or “ordinary.” In Latin, usualis is a third-declension adjective, with neuter nominative usuale.

Usualis has been used across plants and animals to denote representative species, but it is not tied to a particular trait and its interpretation depends on the author and the genus. It signals that the taxon was intended as a typical member of its group rather than highlighting a specific diagnostic character.

In practice, the epithet can appear in multiple unrelated genera, and the same name may be used in different taxa, following the rules of binomial nomenclature. As with all Latin epithets, usage should conform to the governing nomenclatural codes and grammatical agreement.

See also: binomial nomenclature; Latin grammar in taxonomy; species epithet.