Costasiella sp. 4
Known only from Kerama Island, Japan.
Kerama Is. Japan.on Avrainvillea erecta. Depth: 25 m, 7 July 2005. Photo: Atsushi OnoAuthorship details
Rudman, W.B., 2005 (September 12) Costasiella sp. 4 [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/costsp4
September 13, 2005
From: Kathe R. Jensen
Dear Atsushi & Bill,
Concerning message #14733
I doubt very much that this could be the same species as Costasiella mandorahae. The coloration of the present animals seem very distinct whereas C. mandorahae was rather pale, and very small - though sexually mature. So I would guess that this is a new species. Unfortunately I don't have good pictures of C. mandorahae - they were so small I had difficulties focusing.
I agree with Atsushi that Costasiella pallida is rather similar to C. formicaria - although I think C. formicaria has tentacular foot corners (I still don't have Baba's paper in my house).
email@example.comJensen, K.R., 2005 (Sep 13) Re: New? Costasiella from Kerama Island. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14753
My suggestion of Costasiella mandorahae was more in the way of a suggestion. Your drawings were somewhat similar and some of these species seem to be somewhat variable in colour. Concerning Costasiella formicarius - yes it does have tentacular anterior foot corners. Baba likens it to a black ant - hence the name 'formicarius' - and describes it as black with a white patch on the head, between the rhinophores, and with white tips to the cerata.
September 12, 2005
From: Atsushi Ono
I found an interesting Sacoglossan species the other day. At first, I was
convinced that this was Stiliger ornatus. However, I was surprised to see a detailed image of the head after the film was developed. This is a species of Costasiella. It was definitely on Avrainvillea erecta.. Two individuals were observed, and one was photographed
Data: Kerama Is. Japan. Depth 25 m 7 July 2005. Photo: Atsushi Ono
And though it is a personal opinion... Costasiella pallida Jensen, 1985
is very similar to C. formicarius (Baba, 1959). [Please refer to
Baba,1959 The family Stiligeridae from Japan Pablication of the Seto
Marine Biological Laboratory, 7(3).]
Ono, A., 2005 (Sep 12) New? Costasiella from Kerama Island. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14733
This is indeed an interesting discovery. It is possibly Costasiella mandorahae Jensen, 1997, but I would like to see Kathe Jensen's colour slides before commenting further. In her description she says the " body is very lightly coloured ... on the anterior surface of the head is a median orange stripe ... in some specimens there also thin orange stripes along the antero-lateral ridges of the head ... cerata have white tips and a subterminal orange band.. a few iridescent blue dots found on cerata. "
In her drawing there is a broad dark stippled band on the cerata. I don't know what that represents. It is possible your animals are a more densely pigmented form of the same species. Other than that I can find no other species approaching your animal. Until I hear from Kathe I will leave this is the unidentified group.
- Jensen, K. R. (1997) Sacoglossa (Mollusca, Opisthobranchia) from the Darwin Harbour Area, Northern Territory, Australia. In: Proceedings of the Six International Marine Biological Workshop. The marine flora and fauna of Darwin Harbour, Northern Territory, Australia. (Eds: Hanley, J.R., Caswell, G., Megirian, D., Larson, H.K.) Museums and Art Galleries of the Northern Territory and the Australian Marine Sciences Association: Darwin, Australia, Darwin, 163-186.