June 14, 2000
From: Scott Johnson
The first Phyllidia polkadotsa I saw in Hawaii some years ago was brought up in a small shelling dredge from about 100 meters depth. Subsequently, I found a number on shallower reefs, but it is by no means a common species, at least in shallow water. In Hawaii, they live in ledges and caves in coral and lava cliffs. The three photos, h162-1, h162-2, and h162-5, were all taken in Hawaii. There is some variation in the shade of the yellow-orange background color. While I have not yet seen this species here in the Marshall Islands, I found the specimen labelled n002.jpg in Nauru. It was very small and had the look of a juvenile, which is possibly why the zones surrounding the black dots is so white rather than the translucent color seen in the Hawaiian photos. The Nauru specimen does, however, bear the three dorsal ridges, although they are not very distinct.
Interestingly, I went on from Nauru to the Solomons, where I found the specimen labelled s036-1.jpg. This, however, was also small and I think it may be a juvenile Phyllidia ocellata.
Johnson, S., 2000 (Jun 14) Phyllidia polkadotsa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2560
The three ridges seem to be an important character which makes me wonder about its relationship to the black-lined yellow animals Erwin Koehler has sent photos of, which also show these ridges.
I agree with you that the Solomon Ids animal could easily be a juvenile P. ocellata.
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