Pellucidae

Pellucidae is a historical family-name that has appeared in various zoological classifications for different groups of invertebrates. The term derives from pellucidus, Latin for “transparent” or “translucent,” and it was sometimes applied to organisms noted for translucent tissues or shells in early taxonomic literature.

Throughout its use, Pellucidae has been inconsistently circumscribed, with different authors attributing it to mollusks, foraminiferans, or other soft-bodied marine invertebrates. Because of this lack of a stable and universally accepted circumscription, the taxon has not been maintained as a valid, contemporary family in modern classifications.

In current taxonomic references and databases, Pellucidae is generally treated as obsolete, often regarded as a synonym of other families or as a nomen dubium created by early authors without a clearly defined type genus or diagnostic features. Its use today is typically limited to historical or nomenclatural discussions rather than to descriptions of a distinct biological lineage.

The case of Pellucidae illustrates broader issues in taxonomy, including the challenges of historical classifications and the movement toward standardized, monophyletic groupings. When encountered in literature, the term usually signals an old or revised framework rather than a living, recognized taxon.

See also: Taxonomic nomenclature, Nomen dubium, Mollusca taxonomy, Foraminifera.