|A live but partially retracted individual of Onchidella sp.|
|A live and active individual of Onchidella nigricans|
Onchidiidae are a family of small, air-breathing sea (and land) slugs. They are shell-less marine (except of 5 species) pulmonate gastropod molluscs. Onchidiidae is the only family within the superfamily Onchidioidea.
These animals are quite unusual in that they are emphatically not opisthobranchs with gills, as are almost all of the sea slugs. Instead these creatures are pulmonates. They are more closely related to air-breathing land and freshwater snails and slugs than they are to most other sea snails and sea slugs.
This family has no subfamilies (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).
There are 143 species names within the Onchidiidae, but a detailed revision has not been made yet, because as of 2009, the opinion was that there was no living malacologist expert enough on the whole group to properly identify them.
Adult onchidiids lack a shell, although a shell and operculum is present at the larval stage. The mantle cavity is reduced to the point of absence, correlating with a loss of gills, raphes, and other characters usually found in the mantle cavity. The organism is completely detorted.
Most of the species in this family are marine and are found in the intertidal zone on rocky coasts. However, two species live in brackish water and three are terrestrial.
Onchidium typhae (India) and Labbella ajuthiae (synonym in literature: Elophilus ajuthiae) (Thailand) are the only two species in the Onchidiidae that live in brackish water. They can also live in freshwater.
Oncis ponsonbyi (synonym in literature: Platevindex ponsonbyi) and Semperoncis montana (synonym in literature: Platevindex apoikistes and Semperella montana) are the only terrestrial species in the Onchidiidae. They live in high-elevation rainforests in Borneo and the Philippines.
All these slugs breathe air. The marine ones breathe and move around and feed during low tide, when the water recedes and the slugs are exposed to the air.
Genera in the family Onchidiidae include:
- Hoffmannola Strand, 1932
- Labbella Starobogatov, 1976
- Lessonina Starobogatov, 1976
- Onchidella Gray, 1850
- Onchidina Semper, 1885
- Onchidium Buchanan, 1800 - type genus
- Paraoncidium Labbé, 1934
- Paraperonia Labbé, 1934
- Peronia Fleming, 1822
- Peronina Plate, 1893
- Quoya Labbé, 1934
- Scaphis Labbé, 1934
- Semperoncis Starobogatov, 1976
- Synonymized genera
- Arctonchis Dall, 1910: synonym of Onchidella J. E. Gray, 1850
- Elophilus Labbé, 1935: synonym of Labbella Starobogatov, 1970
- Eudrastus Gistel, 1848: synonym of Peronia Fleming, 1822
- Lessonia Labbé, 1934: synonym of Lessonina Starobogatov, 1976
- Occidentella Hoffmann, 1929: synonym of Onchidella J. E. Gray, 1850
- Onchis Férussac, 1821: synonym of Peronia Fleming, 1822
- Oncidiella P. Fischer & Crosse, 1878: synonym of Onchidella J.E. Gray, 1850
- Oncidina Plate, 1893: synonym of Onchidina Semper, 1882
- Oncidium Agassiz, 1846: synonym of Onchidium Buchannan, 1800
- Oncis Plate, 1893: synonym of Platevindex H. B. Baker, 1938
- Peronella Mörch, 1863: synonym of Onchidella J.E. Gray, 1850
- Peroniella Starobogatov, 1976 : synonym of Onchidella J. E. Gray, 1850
- Platevindex Baker, 1938 : synonym of Oncis Plate, 1893
- Quoyella Starobogatov, 1976: synonym of Quoya Labbé, 1934
- Semperella Labbé, 1934 synonym of Semperoncis Starobogatov, 1976
- Watsoniella Hoffmann, 1928: synonym of Hoffmannola Strand, 1932
- Rafinesque C. S. (1815). Analyse de la nature ou tableau de l'univers et des corps organisés. Palerme, 223 pp., page 142.
- Dayrat B. (2009). "Review of the current knowledge of the systematics of Onchidiidae (Mollusca: Gastropoda: Pulmonata) with a checklist of nominal species". Zootaxa. 2068: 1–26., preview.
- Morton, Brian (1992). The Marine Flora and Fauna of Hong Kong and Southern China III___ Fouling and pollution, morphology, behavious and physiology, Hoi Ha Wan. Hong Kong University Press. ISBN 978-962-209-295-2.
- Chung D. J. D.: Molluscan 'Love darts'? Hawaiian Shell News, 1986 May, Vol 34(5), pages 3-4. http://s190418054.onlinehome.us/HSN/1980/8605.pdf[permanent dead link]
- Barker G. M.: Gastropods on Land: Phylogeny, Diversity and Adaptive Morphology. in Barker G. M. (ed.): The biology of terrestrial molluscs. CABI Publishing, Oxon, UK, 2001, ISBN 0-85199-318-4. 1-146, cited pages: 139 and 142.
- World Register of Marine Species : Onchidiidae; accessed 13 September 2010 (with modifications).
- "Onchidella". Integrated Taxonomic Information System., accessed 13 September 2010.
- Britton K. M. (1984). "The Onchidiacea (Gastropoda, Pulmonata) of Hong Kong with a worldwide review of the genera". Journal of Molluscan Studies. 50 (3): 179–191. abstract.
- Media related to Onchidiidae at Wikimedia Commons