Nanuca sebastiani
Marcus, 1957

Family: Glaucidae


Brazil, Caribbean [Curacao, Bahamas, Barbados, Florida]


off Deerfield Beach, Florida, USA. Depth approx 10 feet. Length smaller than 1/2 inch. March, 2003. Photo: Linda Ianniello

Small aeolid seldom larger than about 12mm. The body is a translucent greenish colour with a distintive pattern of white patches, most of which have a yellow central spot or line. The long slender oral tentacles are banded and patched with creamy white dusting, and the upper half of the rhinophores are also dusted with creamy white. The rhinophores have three or four wide rings or brackets which are notched in the posterior midline. The branckets do not sit horizontally but fold slightly upwards to give the rings/brackets a cup-shaped appearance. The cerata are arrangd in four groups on eah side of the body. The first 3 pairs are arranged about equally down the body but the 4th pair is close behind the 3rd. The cerata are cylindrical and taper to a blunt tip. The ceratal wall is coloured with thin cream white longitudinal lines which stop just short of the translucent white tip.

The colour pattern on the body is very distinctive. There is a pattern of white spots, eah with a yellow centre running down the dorsal midline. There are 2 spots on the head in front of the rhinophores, one between the rhinophores, and 2 between the rhinophores and the first ceratal group. There are then 3 spots between the 1st and 2nd ceratal groups, and another 3 between the 2nd and 3rd eratal groups. There is a single spot between the 3rd and 4th ceratal groups, and then 3 behind the last group of cerata. From the middle spot in the space between the ceratal groups 2 or 3 spots run down each side of the body to form a cross-like pattern. This pattern of spots seems to be consistent in all the descriptions of the species. The cross-like pattern is particularly noticeable in the Florida specimen photographed here because the spots are more elongate than usual, in some cases running together to form elongate irregular lines.

• Edmunds, M. & Just, H. (1983) Eolid nudibranchiate Mollusca from Barbados. Journal of Molluscan Studies, 49(3): 185-203.
• Marcus, Er. (1957) On Opisthobranchia from Brazil (2). Journal of the Linnean Society of London, Zoology, 43(292): 390-486.
• Marcus, Ev. & Marcus, Er. (1963) Opisthobranchs from the Lesser Antilles. Studies on the Fauna of Curacao and other Caribbean Islands, 19(79): 1-76.
Redfern. C., 2001 Bahamian Seashells: a Thousand Species from Abaco, Bahamas.

Authorship details
Rudman, W.B., 2003 (April 14) Nanuca sebastiani Marcus, 1957. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

Nanuca sebastiani from Florida

April 16, 2003
From: Linda Ianniello

Hi, Dr. Bill,
Here is another one from Florida that I think is Nanuca sebastiani. I used the photo and description in Colin Redfern's book to identify it. It was very small, less than 1/2 inch and was found in March, 2003 off Deerfield Beach, Florida at a depth of about 10 feet. It was just crawling on the bottom.
Linda Ianniello

Ianniello, I., 2003 (Apr 16) Nanuca sebastiani from Florida. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Linda,
Yes this is Nanuca sebastiani, another new find for Florida. This is another of those problematic species described by the Marcuses on the basis of preserved specimens (Marcus, 1957). Fortunately in this case, they later identified an animal, which had a description of its living colour (Marcus & Marcus, 1963), with Nanuca sebastiani, so its identity can be tied to that later description.
Best wishes,
Bill Rudman

Rudman, W.B., 2003 (Apr 16). Comment on Nanuca sebastiani from Florida by Linda Ianniello. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from