Pleurobranch from Russian Pacific

January 16, 2001
From: Valeri Darkin

Dear Sirs,

I would like to ask for your help to identify this species of slug photographed in the Bay of Peter the Great near Vladivostok, Russian Pacific Coast. Depth was 5 meters, on mussel bed.

If you have any idea what is the latin name of this Slug, please, let me know. I will be overseas traveling January 23 - February 25, 2001 for dive convention (DEMA Show).

Best regards
MR. Valeri (Val) Darkin
Diving Instructor, Marine Biologist, U/W Photographer, Videographer, Shell collector Conus darkini may ring the bell).

Darkin, V., 2001 (Jan 16) Pleurobranch from Russian Pacific. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Val,
This is a most interesting find. It is a pleurobranch (Order Notaspidea), commonly called 'Side-gilled Slugs' because their single gill lies on the right side of the body below the mantle skirt. If you have a look at the species in the Order Notaspidea in the Species List you will get some idea of the variation. Have a look at Pleurobranchus forskalii for a good photo of the gill.

Your species is most likely a species of Pleurobranchus or Berthella but we would need to look at its anatomy to be sure. Unformtunately the only external character between the two genera concerns the shape of the gill (species of Pleurobranchus have tubercles) but unfortunately we can't see that in a photo either.

Your animal looks very much like Berthella californica (Dall, 1900) which is found from Alaska to Baja California in Mexico. That species is the only one I know of that has white raised spots on the mantle and foot, and a white edge as in your animal. I guess it would not be the first Alaskan species found on the Pacific coast of Russia. If it is that species I would think it is a rather interesting new record.

I am sure my North American colleagues can give us a better idea on the likelihood of your specimen being the same species.

I look forward to you sending us some more interesting photos from your part of th world.
Best wishes,
Bill Rudman

Rudman, W.B., 2001 (Jan 16). Comment on Pleurobranch from Russian Pacific by Valeri Darkin. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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