Atys naucum (Linnaeus, 1758)

Description

A cephalaspidean with a fragile, translucent papery shell reaching about 35 mm in length, ovoid and umbilicate at both ends and crossed by very fine transverse striations. The shell often shows a faint milky glaze. Soft parts unpigmented to faintly fawn, fully retractable into the shell. Found on sandy substrata in shallow water.

Distribution

Indian Ocean and western Pacific.

Etymology

The specific epithet naucum is the Latin for the soft pulpy interior of a nutshell, used proverbially to mean "a trifle" or "something insubstantial" — apparently in reference to the fragile papery shell.

Remarks

Originally described as Bulla Naucum in Systema Naturae, 10th edition (Holmiae, 1758) and reprised in the 12th edition (1767: 1184 §375) as "B. testa rotundata pellucida transversim substriata, utrinque umbilicata", with the type locality given simply as Asia.

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References

• Bulla Naucum, Linnaeus C. (1758). Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. Tomus I. Laurentius Salvius, Holmiae. 824 pp.
• Atys naucum, Terrence Gosliner, Ángel Valdés and David Behrens. (2018). Nudibranch and Sea Slug Identification Indo-Pacific 2nd Edition. New World Pubns Inc.
• Oskars T.R., Too C.C., Rees D., Mikkelsen P.M., Willassen E. & Malaquias M.A.E. (2019). A molecular phylogeny of the gastropod family Haminoeidae sensu lato (Heterobranchia: Cephalaspidea): a generic revision. Invertebrate Systematics 33(3): 426-472.