Limapontia depressa
Alder & Hancock, 1862

Order: SACOGLOSSA
Superfamily: LIMAPONTIOIDEA
Family: Limapontiidae

DISTRIBUTION

Atlantic coast of Europe from Baltic to SW France - on saltmarshes.

PHOTO

Locality: Church Island, Menai, Anglesey, intertidal, Wales, U.K., Irish Sea, 17 October 2009, intertidal mud flat, full salinity. Length: 3.5 mm. Photographer: Ian F. Smith. [a = anus]

This small inconspicuous sacoglossan grows to approximately 6 mm in length. It usually ranges in colour from dark brown to black with paler regions around the eyes, but there is a variety reported which is much paler in colout and in which the darker digestive gland can be seen through the body wall.

Externally it can be distinguished from L. capitata and L. senestra by the lack of any sign of head tentacles, although this is not always easy when comparing it with L. capitata. However L. depressa is distinct in the position of the anus and renal openings. In all three species the openings are approxinately in the dorsal midline. In L. depressa the anus is near the posterior end of the body while the renal opening is some distance away, about one-third of the length of the body from the posterior tip. In the other two species, both openings are quite close together about one-third of the length of the body from the posterior tip.

Thompson reports it to be a common inhabitant, with Alderia modesta, of British saltmarshes as well as continental Europe. It is rarely found in pools, but usually on damp mud, crawling and feeding on the alga Vaucheria. Its salinity tolerance is not great preferring approx 25% seawater. This species has swimming, feeding planktotrophic larvae.

• Chia, F. S. (1971). Oviposition, Fecundity, and Larval Development of three sacoglossan opisthobranchs from the Northumberland Coast, England. The Veliger 13(4): 319-325.
• Hartog, C. D. and C. Swennen (1952). On the occurrence of Alderia modesta (Lovén) and Limapontia depressa A. & H. on the salt marshes of the Dutch Waddenzee (Gastropoda, Nudibranchia). Beaufortia, Zoological Museum, Amsterdam 19: 1-3.
• Quick, H. E. (1950). Observations on Limapontia. Proceedings of the Malacological Society of London 28(4-5): 134-138
• Thompson, T.E. (1976) Biology of Opisthobranch Molluscs. Volume 1. The Ray Society, London. 207pp.

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