Elysia cf. nigrocapitata from Sagami Bay

September 25, 2000
From: Cynthia Trowbridge

Dear Bill,

During this past May, I had the wonderful opportunity to visit Yoshi and Yakko Hirano (Kominato Marine Laboratory, Chiba University, Japan). The species richness of Sagami Bay was wonderful. Yoshi kindly photographed several for posting to the Sea Slug Forum. If anyone could assist us in confirming the identity of Elysia cf. nigrocapitata, we would be very appreciative. It is one of the most beautiful ascoglossans I have ever seen.

Elysia cf. nigrocapitata (Baba 1957) (Izumi-midorigai):
We collected three specimens in high intertidal rock pools on the Miura Peninsula, Japan (May 2000). The slugs were associated with filamentous green algae. The body was yellowish-green and darker on the outer surface of the parapodia and tip of the tail. The pattern on the head did not precisely match that shown by Baba (1957) so we are tentative in our identification.
Distribution: Elysia nigrocapitata occurs in Japan and Hong Kong (Baba 1957, Jensen 1998).

• Baba, K. (1957) The species of the genus Elysia from Japan. Publ Seto Mar
Biol Lab, 6
: 69-74.
• Jensen, K.R. (1998) Zoogeographic affinities of Hong Kong Opisthobranchia (Mollusca, Gastropoda). In: Morton B (ed.) The Marine Biology of the South China Sea. Hong Kong University Press, Hong Kong, p 43-55.



Trowbridge, C., 2000 (Sep 25) Elysia cf. nigrocapitata from Sagami Bay. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3063

Dear Cynthia,
Thanks to you and Yoshi for the interesting photos. It is very useful to see photographs of Japanese material to compare it with specimens from other parts of the Pacific. The subtleties of colour pattern and shape are often lost in publishes descriptions even when they are accompanied by detailed drawings and paintings.

I have posted your information on Elysia trisinuata and Aplysiopsis minor separately.
Best wishes,
Bill Rudman.