Cuthona anulata from Japan

August 13, 2002
From: Nishina Masayoshi

Dear Bill,
I have attached photos of Cuthona anulata (Baba, 1949). Baba described this species in Opisthobranchs of Sagami Bay and there is an illustration. The oral tentacles in his illustration are long and extend in front of the head, while in my spcimens they are shorter and extend to the side. Baba didn't describe the dorsolateral color which is translucent clear with scattered white irregularly sized patches.

Date: 3 Aug 2002
Loc: Echizen coast, Fukui prif. Japan
Lengh: 6mm
Depth: 4m
Water temp: 27C degree
Photo: M. Nishina
The uppermost photo was taken at the place where Baba's original animal was found.

Best Regards,
Nishina Masayoshi

Masayoshi, N., 2002 (Aug 13) Cuthona anulata from Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Nishina,
Thakns for another interesting species. I think this another of Baba's species which has not bee reported on since his original description. Although we would need to look at its anatomy to be sure, it certainly fits Baba's description well. The main point of difference is the dull brown ceratal digestive gland in the painting in Baba's book. I would consider this most likely to be the result of eating different hydroids, or perhaps not eating enough. The shape of the radular teeth, the ceratal arrangement, and the rounded anterior foot corners, support the idea that this is more appropriately considered a Cuthona rather than a Cratena
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Aug 13). Comment on Cuthona anulata from Japan by Nishina Masayoshi. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Cuthona anulata

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