Medialidae

Medialidae is a zoological family name that has appeared in historical classifications but is not recognized in modern taxonomy. The name is formed from the Latin medialis, meaning "middle," and was used by some 19th-century taxonomists to group organisms they identified by central or middle-body features. Because the diagnostic criteria varied among authors, the circumscription of Medialidae was inconsistent and often overlapped with other families.

Over time, as taxonomic methods advanced and consensus criteria for family-level groups were refined, the use of Medialidae faded. In current classifications, the name is not recognized as a valid family in widely used taxonomic references. In some cases, Medialidae has been considered a junior synonym of another, better-established family, or it has been deemed a preoccupied or unnecessary name that requires replacement.

As a result, there are no stable, modern genera assigned to Medialidae in contemporary catalogs. The term remains of interest mainly to historians of taxonomy and to those studying nomenclatural rules and the history of zoological classification.

See also: Taxonomic nomenclature; Obsolete taxa; Preoccupied names.

Medialidae illustrates how taxonomic groups can be proposed, revised, or discarded as scientific understanding evolves.