Proctonotus mucroniferus
(Alder & Hancock, 1844)

Suborder: ARMININA
Family: Zephyrinidae


Known from a very few records [less than 6] from the British Isles and Atlantic coast of France. Reported in Forum from Norway.


Locality: Vikaneset, Kristiansund, 6-7 metres, Norway, Atalntic, 28 April 2007, Rocky, Kelp forest. Length: Ca. 10 mm. Photographer: Christian Skauge.

Proctonotus mucroniferus has seldom been recorded, and little is known of its anatomy, and even less about its biology. As far as I know its radular morphology is still unknown. Thompson & Brown (1984) summarise the available information.

It is a translucent to transparent brown with scattered darker brown patches. It is similar to Janolus hyalinus in shape and colour but lacks the crest [or 'caruncle'] between the rhinophores. The rhinophores are wrinled and nodulose. This species has a number of rows of cerata around the edge of the body, including the anterior end. The cerata are somewhat nodulose and the tip is truncated and button-like. There is a single duct of the digestive gland running into each ceras, except those at the anterior end of the body. 

  • Alder, J. and Hancock, A. (1844) Description of a new genus of Nudibranchiate Mollusca, with some new species of Eolis. Annals and Magazine of Natural History 13: 161-166.
  • Thompson, T. E. and Brown, G. H. (1984) Biology of Opisthobranch Molluscs Vol 2. 229 pp. 41 Pls. Ray Society 156.

Best wishes,
Bill Rudman

Authorship details
Rudman, W.B., 2007 (May 8) Proctonotus mucroniferus (Alder & Hancock, 1844). [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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  1. Proctonotus mucroniferus? from Norway
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