Protaeolidiella atra from Japan

Dear Yasuhiro,
Thank you very much for sending the interesting photos of Protaeolidiella atra. When I looked at your website after your last message, I was very interested to see the photos of Protaeolidiella. When I reviewed these animals (Rudman, 1990) I considered the Japanese P. atra, without a white stripe, and the Australian P. juliae, with a white stripe to be the same species. The white-striped form is quite common throughout the indo-West Pacifc. Dr Baba (1992) still considers the Japanese animal, illustrated here, to be a distinct species. From Baba's illustrations, there do not seem to be any easily defined anatomical differences. If any one has seen both colour forms together, I would be very interested to hear of it. Dr Baba reports both striped and unstriped animals from Japan. One interesting difference is that the unstriped animals grow to over 50mm which is about twice as long as the largest striped specimen I have seen. Perhaps the striped animals are only found on Solanderia fusca.

The hydroid in Yasuhiro's photos is identified in Baba (1992) as Solanderia secunda (Inaba).

Best wishes,
Bill Rudman.

Yasuhiro's website is at http://www.e-net.or.jp/user/yasuhiro/ It is mostly in Japanese, but there is a section with nudibranch photos at:
http://www.e-net.or.jp/user/yasuhiro/diving/aquarium/umiusi/main.html

References:
•Baba, K. (1992) Comment on the taxonomy of Protaeolidiella atra Baba, 1955 and an allied species from Japan. Report of the Sado marine Biological Station, Niigata University, 22: 29-35.
•Rudman, W.B. (1990.) Protaeolidiella atra Baba, 1955 and Pleurolidia juliae Burn, 1966; one species, two families (Nudibranchia). Journal of Molluscan Studies, 56(4): 505-514.