Palisa sp. from Heron Island

April 21, 2005
From: Julie Marshall


Dear Bill,

Here are photos of another species which Bob Burn found whilst sieving alga (and obviously some hydroids) attached to coral clumps on the reef flat at Heron Island [Great Barrier Reef] at low tide when he was with me there in March.

The photos with this message are of what we consider to be a species of Palisa. It was 9 mm and is distinguished by the large rhinophores, which have ten rows of long papillae on their posterior side, and by the slender and curved cerata. The general body colour was translucent white with opaque white blotches all over, and these are repeated on the head and the rhinophores. The oral tentacles are alternately translucent and opaque white. The cerata are dark brown due to the digestive gland with bluish-white and opaque white patches.

Locality:  Heron Island, Great Barrier Reef, Queensland, Australia. Pacific Ocean. Depth: Intertidal. Length: 9 mm. 16 March 2005. Intertidal. Photographer: Julie Marshall

Best wishes,
Julie Marshall

juliemarshall@netspace.net.au

Marshall, J.G., 2005 (Apr 21) Palisa sp. from Heron Island. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13531

Thanks Julie,
Palisa Edmunds (1964) seems to be a problematical genus based on one or perhaps two Caribbean species, Palisa papillata Edmunds, 1964 and P. kristenseni (Marcus & Marcus, 1963). Edmunds noted tuberculate rhinophores, radular teeth lacking a prominent cusp, and details of the reproductive system as important but was not sure which charcters would turn out to be of generic importance, and which characters would be just of specific value.  Later (Edmunds & Just, 1983) placed Moridilla kristenseni Marcus & Marcus in Palisa and decided it was a senior synonym of Palisa papillata, which means we still have problems in defining Palisa. Certainly your animal has tuberculate rhinophores and appears to have the cerata arranged in arches, so it is possible it is a species of Palisa, but we would need to have a look at its anatomy to confirm it.

  • Edmunds, M. (1964) Eolid mollusca from Jamaica, with descriptions of two new genera and three new species. Bulletin of Marine Science of the Gulf and Caribbean, 14: 1-32.
  • Edmunds, M & Just, H (1983) Eolid nudibranchiate Mollusca from Barbados. Journal of Molluscan Studies, 49(3): 185-203.
  • Marcus, Ev. & Marcus, Er. (1963) Opisthobranchs from the Lesser Antilles. Studies on the Fauna of Curacao and other Caribbean Islands, 19(79): 1-76.
Best wishes,
Bill Rudman Rudman, W.B., 2005 (Apr 21). Comment on Palisa sp. from Heron Island by Julie Marshall. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13531

Factsheet

Palisa sp. 1

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