Rostanga orientalis? from Japan

March 12, 2000
From: Yasuhiro Shirai

Dear Bill,
I attached 2 image file in this mail. I think this animal is Rostanga sp perhaps Rostanga orientalis?.

Could you please identify it for me?

Location: Shima Pref. Mie, Japan (Kii Peninsula, east coast)
Length: 20mm
Water temperature: 15C
Date Feb.2000
Depth: 3m Crawling on rock.

Best regards,
Yasuhiro Shirai

Shirai, Y., 2000 (Mar 12) Rostanga orientalis? from Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Yasuhiro,
Your animal is definitely a species of Rostanga and could easily be Rostanga orientalis, which has similarly shaped rhinophores, and can have scattered white and/or brown specks.

Unfortunately, species of Rostanga are quite difficult to separate on external characters, although very simple to distinguish anatomically. All the species we have information on are also easy to distinguish on the shape of their egg masses.

So at this stage all I can say is it is possibly Rostanga orientalis.
Best wishes,
Bill Rudman.

Rudman, W.B., 2000 (Mar 12). Comment on Rostanga orientalis? from Japan by Yasuhiro Shirai. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Rostanga spp.

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