Pusillus

Pusillus is a Latin adjective meaning small, tiny, or diminutive. In biological nomenclature, it is commonly used as a species epithet within the binomial name of a taxon to indicate that the organism is smaller than a closely related form or represents a diminutive member of a group.

In Latin grammar for taxonomy, adjectives must agree with the gender of the genus. Therefore, pusillus appears as pusillus (masculine), pusilla (feminine), or pusillum (neuter) to match the corresponding genus name. This agreement reflects the long-standing practice of Latinizing descriptive terms in scientific naming.

As a descriptor, pusillus does not constitute a taxon or rank on its own. It functions as part of a name to convey a characteristic of the species or variety, most often relative small size within a genus or group. The epithet can appear across a wide range of taxa, including both animals and plants, and across different taxonomic levels where Latin epithets are used.

The term exemplifies the broader tradition in taxonomy of using Latin descriptive adjectives to summarize notable traits of organisms in a standardized, species-identifying form. Its meaning is tied to size rather than to a specific biological function or phylogenetic position.

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