Siphopteron fuscum from Japan

February 26, 2000
From: Yasuhiro Shirai

Dear Bill,

Thanks for your help. I have sometimes found this opisthobranch at Shima Prefecture, Mie, Japan. I think that it is Siphopteron sp. but I don't know this animal's real name. I searched in some books, but without success. Could you please identify it for me?

Location: Shima Pref. Mie, Japan (Kii Peninsula, east coast)
Length: 4-10mm
Water temperature: 14C
Date Jan. 2000-Feb.2000
Depth: 2-3m
Crawling on rock or crawling on seaweed.

Yasuhiro Shirai

Shirai, Y., 2000 (Feb 26) Siphopteron fuscum from Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Yasuhiro,
This is an interesting find. I think it is an animal described by Baba & Tokioka in 1965 as Gastropteron fuscum. I don't know of any record of it being found since then.

In Terry Gosliner's revision of the family (1989) he placed it in the genus Siphopteron. It is certainly a spectacular looking, and easily recognised, species.

Best wishes,
Bill Rudman.

Rudman, W.B., 2000 (Feb 26). Comment on Siphopteron fuscum from Japan by Yasuhiro Shirai. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Siphopteron fuscum