Re: Aplysiopsis minor from Sagami Bay

May 19, 2007
From: Cynthia Trowbridge

Concerning message #4304:

Dear Bill and Kathe,
When Kathe made her comment in 2001, I was surprised because I had not seen any stylet in the live animal and the dorsal view did not fully illustrate the rhinophore shape. I was certain that the "stylet" was merely a scratch on the plastic petri dish.

My delay in answering this message was that the photographed specimen was not kept so we needed to collect more specimens from the same pools in the same season. We eventually did find several more specimens. The radular teeth were indeed sabot-shaped. Thus, I do believe that our specimens are Aplysiopsis minor, including the original one.

Thanks for your patience on this one.


Trowbridge, C.D., 2007 (May 19) Re: Aplysiopsis minor from Sagami Bay. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Cynthia,
This is a good example of how taxonomy sometimes takes awhile to progress when animals are not available. Not being an expert on these animals I had a look at Baba's description and some of Kathe's papers to clarify in my own head the distinction between Ercolania and Aplysiopsis - the two genera with sabot-shaped teeth. I hope Kathe, that things haven't changed (Jensen, 1993), but you differentiate these two genera by a number of characters. The rhinophores are 'rolled or folded' in Aplysiopsis but never in Ercolania. The penis in Ercolania has a short curved stylet but in Aplysiopsis it has a long flagellar extension, and while Ercolania has albumen gland branches in the cerata, Aplysiopsisdoes not.

If these characters are correct I am not sure what this animal is. Kathe describes the penial papillae as a 'thin curved stylet' [= Ercolania] but could it be a 'long flagellar extension' [= Aplysiopsis]? As to the rhinophores I think we need some more information - I can't tell from the dorsal photos whether they are 'rolled or folded'. Which brings us to the albumen gland branches. Are the white branches on the cerata pigment marks or are they internal ducts? I note that Baba specifically says there are no albumen branches in his animals.

Cynthia, can you tell us more about the rhinophores and the albumen gland? If so we might be able to end this 6 years and 1 week discussion - not that it isn't enjoyable of course.

  • Jensen, K.R. (1993) Sacoglossa (Mollusca, Opisthobranchia) from Rottnest Island and central Western Australia. In: Proceedings of the 5th International marine Biological Workshop: The marine Flora and Fauna of Rottnest Island, Western Australia. (Eds: Wells, F.E; Walker, D.I; Kirkman, H; Lethbridge, R) Western Australian Museum, Perth, 207-253.

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (May 19). Comment on Re: Aplysiopsis minor from Sagami Bay by Cynthia Trowbridge. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Aplysiopsis minor

Related messages

  1. Re: Aplysiopsis minor from Sagami Bay
    From: Kathe R. Jensen, May 11, 2001
  2. Aplysiopsis minor from Sagami Bay
    From: Cynthia Trowbridge, September 25, 2000

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