Siphopteron fuscum
(Baba & Tokioka, 1965)

Superfamily: PHILINOIDEA
Family: Gastropteridae


Known only from Japan.


Shima Pref. Mie, Japan (Kii Peninsula), Depth: 2-3m, Length: 4-10mm, Jan - Feb. 2000. PHOTO: Yasuhiro Shirai.

Originally described from a single 4mm long specimen [Etizen Coast, Japan Sea side of Honshu Id]. The dorsal hump and outer surfaces of the parapodia were deep choclate brown and their were irregular white markings, towards the margin in the case of the paraoodia. The tip of the siphon and the edge of foot and parapodia were described as deep vermillion. I don't think there is much doubt that the animal photographed here is S. fuscum.

•Baba, K. & Tokioka, T. (1965). Two more species of Gastropteron from Japan, with further notes on G. flavum (Gastropoda: Opisthobranchia). Publications of the Seto Marine Laboratory, 12(5): 363-379.

Authorship details
Rudman, W.B., 2000 (February 25) Siphopteron fuscum (Baba & Tokioka, 1965). [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

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