Re: Aplysiopsis? from North Sulawesi

April 9, 2010
From: Cynthia Trowbridge

Concerning message #21790:

Dear Bill,

I just came across this message about Hermaea vs. Aplysiopsis.

Of the 9 or so described Aplysiopsis species, I have feeding information for 7; all feed on Chaetomorpha, Cladophora, and allies. These are all septate green algal filaments (i.e., they have discrete cells). Next week the Hiranos and I will be presenting a talk at the malacology meetings in Japan on the 4 local Aplysiopsis species as well as the other members of this feeding guild (several Ercolania spp. and Elysia spp.). I do not have any information about A. brattstroemi (Marcus, 1959) or A. elegans (Deshayes, 1864) but would be surprised if they ate red algae (someone would have remarked on this diet as unusual).

Regarding Hermaea spp., they do not all eat red algae but most do. One exception is Hermaea vancouverensis that eats diatoms (Isthmia) that cover macroalgae during the summer in the NE Pacific and Hokkaido. This was discussed on the forum a few years ago [message #15995].

The Hiranos and I have a paper coming out in Veliger that reviews the red algal diets of sacoglossans around the world [e-print will be available soon]. At this point, there are records of Hermaea (most species), Stiliger (some species), and Elysia (some species)that feed on ceramialean red algae. Hermaea spp. have been understudied as they are extremely cryptic and the red algae are taxonomically challenging.

Anyway, the bottom line is that the specimen is probably Hermaea. The odd color is probably due to the breakdown of the red algal chloroplasts...the pigments change from red to peachy-orange as they break down due to low tide exposure during sunny periods.

  • Trowbridge, C.D., Hirano, Y.J., & Hirano, Y.M. 2010. Sacoglossan opisthobranchs on northwestern Pacific shores: Stiliger berghi Baba, 1937, and Elysia sp. on filamentous red algae. The Veliger 51: 43-62.

All the best,

Cordially,
Cynthia

sacoglossans@ymail.com

Trowbridge, C.D., 2010 (Apr 9) Re: Aplysiopsis? from North Sulawesi. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/23425

Dear Cynthia,

Thanks for this interesting contribution.  It reminded me of a note I made to myself in October 2008, but never follwed it through, concerning message #19041, which also suggests Aplysiopsis sp.1 feeds on filamentous red algae.

I wrote:

"I suspect that Aplysiopsis sp. 1 is a form of Hermaea zosterae, which as I discuss in a separate message is probably a synonym of Hermaea noto [#5195]. Interestingly the evidence suggests that Aplysiopsis sp. 1 feeds on filamentous red algae, which is what species of Hermaea normally feed on"

Before I change Aplysiopsis sp 1 to Hermaea sp 2 I would be interested in your views on this suggestion. Perhaps I should call it Hermaea cf. zosterae?

Best wishes,
Bill Rudman

Rudman, W.B., 2010 (Apr 9). Comment on Re: Aplysiopsis? from North Sulawesi by Cynthia Trowbridge. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/23425

Factsheet

Aplysiopsis sp. 1

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