Aplysia kurodai & A. juliana

June 14, 2002
From: Ron Noseworthy

Dear Dr. Rudman,
I am living on Cheju Island, South Korea. I am studying the molluscs of the island and am currently working on Aplysia. I am trying to determine whether or not A. kurodai is a separate species or a synonym of A. juliana. Okutani, [Marine Mollusks in Japan, 2000] lists both species, and states that A. juliana secretes only a white fluid but A. kurodai secretes a purple fluid. Also, the parapodia are fused posteriorly in A. juliana but not fused posteriorly in A. kurodai.

Any information you can give me would be greatly appreciated.
Ron Noseworthy,
Sogwipo, Chejudo,
Republic of Korea.


Dear Ron,
In my reply to Tony Wright's message about an Aplysia from Taiwan, I discuss two species reported by Baba (1937) from Japan (Aplysia sibogae Bergh, 1905 and Aplysia kurodai Baba, 1937) both of which I thought could be colour forms of A. juliana. Both were reported to secrete a white fluid from the opaline gland which is usually only obvious in species like A. juliana which do not secrete purple ink as well. On re-reading Baba's paper I see that although he doesn't mention purple secretions for A. kurodai, he does mention that it has a purple gland and that the parapodia are separated behind. From that I woud conclude that the animal he identified as Bergh's A. sibogae was actually A. juliana and his new species, A. kurodai, is not.

Apart from the fused posterior lobes of the parapodia and the lack of a purple gland in A. juliana, that species can also be distinguished by the way the rear part of the foot forms a sucker - the rest of the body often been held above the substrate. Aplysia juliana is very variable in colour, ranging from a uniform black to light brown with whitish patches.

In short A. kurodai is definitely distinct from A. juliana. The photo in Okutani, (if correctly identified), of A. kurodai certainly looks distinctly dfferent from other speces of Aplysia I have seen alive. However producing purple ink and having the parapodia separate posteriorly, are characters found in most species of Aplysia. Until someone is able to review the genus worldwide I cannot say whether A. kurodai is endemic to Japan and other parts of the NW Pacific, or whether it is a more widely spread species and so may have an earlier name from somewhere else. Some photos of this animal would be much appreciated, and any news on your research activities would be very welcome.

• Baba, K., (1937) Opisthobranchia of Japan (I). Journal of the Department of Agriculture, Kyushu Imperial University, 5(4): 195-236. (Pl.4)

Best wishes,
Bill Rudman.

Rudman, W.B., 2002 (Jun 14). Comment on Aplysia kurodai & A. juliana by Ron Noseworthy. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7230


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