Rostanga? from Japan

January 14, 2002
From: Rie Nakano

Dear Dr.Rudman,

Is this a species of Rostanga?
In Hachijo Is. Japan, from November to January, we see this animal commonly.

Length: 8mm
Depth: 5m
On the rocky reef(shallow water)


Nakano, R., 2002 (Jan 14) Rostanga? from Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Rie,
I am pretty sure that this is a species of Rostanga but it is difficult to identify them without looking at their anatomy. At present there are two species reported from Japan (Baba, 1991). One of these, R. orientalis, is orange-red and the other, R. risbeci, is black. However there are sure to be more species found there. One obvious difference is that your animal has horizontal lamellae on the rhinophores while R. orientalis has vertical lamellae. R. risbecia has horizontal lamellae, but it is black. If this animal is quite common perhaps you could take a photo of it on its sponge, and if you are lucky also photograph its egg ribbon.

• Baba, K. (1991) Review of the genus Rostanga of Japan with the description of a new species (Nudibranchia: Dorididae). Venus, The Japanese Journal of Malacology 50(1): 43-54. (Figs 1-5, Pl.1)

Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Jan 14). Comment on Rostanga? from Japan by Rie Nakano. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Rostanga? sp. 2

Related messages

  1. Rostanga sp. - more photos
    From: Rie Nakano, January 18, 2002

Show factsheet and all related messages