Cuthona pustulata
(Alder & Hancock, 1854)

Order: NUDIBRANCHIA
Suborder: AEOLIDINA
Family: Tergipedidae

DISTRIBUTION

North Atlantic - France, British Isles, Denmark, Iceland, Nova Scotia, Maine. North Pacific - also reported from British Columbia.

PHOTO

Upper: Eastport, Passamaquoddy Bay, Maine, USA. Atlantic Ocean. Depth: 10 to 12 metres. Length: approximately 15 mm. May/June 2004. Gravel and debris strewn bottom near remains of old pier. Photographer: Alan Shepard. Lower: Woody Beach, Eastport, Passamaquoddy Bay, Maine, USA, Atlantic coast. Depth: 15 meters. Length: 12 mm. 12 July 2005. Rocky bottom, high current. Photographer: Alan Shepard

This small species of Cuthona, reaching approximately 20 mm in length, was originally described from England, and its anatomy and natural history were reviewed by brown (1980). Its skin is translucent clear, the whitish viscera showing through the body wall.   There are scattered irregularly shaped white spots on the cerata, rhinophores and oral tentacles, and the ceratal digestive gland duct may be yellow, pink or light brown in colour. In the British Isles the normal colour of the ceratal digestive gland is yellow. The ceratal tips are often swollen and blubtly rounded. In England, Brown reports it to live on and feed on the hydroid Halecium muricatum. He also provides indirect evidence that this species has non-pelagic larvae.

Gosliner & Millen (1984) identify specimens of a similar looking animal from the Pacific coast of Canada as Cuthona pustulosa, and Bleakney (1996) identifies it from the Atlantic coast of Nth America as well. In many ways they look very similar but we probably need to look more closely at the populations before the identity can be confirmed. Both Nth American populations have planktotrophic larvae and from Millen & Gosliner's description, the teeth of the Nth Pacific animals are about half the size of English specimens. It is possible that English animals have planktotrophic larvae as well, and the tooth size may prove to be more similar, but it certainly worth drawing attention to the fact that there are still questions to be answered before the identity of Nth Amercian animals is confirmed.

• Bleakney, J. S. (1996) Sea Slugs of Atlantic Canada and the Gulf of Maine. Halifax, Nova Scotia, Nimbus Publishing & Nova Scotia Museum.  1-216.
• Brown, G. H. (1980) The British species of the aeolidacean family Tergipedidae (Gastropoda: Opisthobranchia) with a discussion of the genera. Zoological Journal of the Linnean Society, 69: 225-255.
• Gosliner, T. M. and Millen, S. V. (1984) Records of Cuthona pustulata (Alder & Hancock, 1854) from the Canadian Pacific. The Veliger, 26: 183-187.

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