Known from Western Australia [Rottnest Id., Houtman Abrolhos Ids., Shark Bay].
Rat Island, Houtman Abrolhos Ids, 2-4 meters, Western Australia, Indian Ocean, Length: 15 mm, 21 July 2004. near shore, coral rubble and stones. Photo: Marta Pola
This species is known only from Western Australia. The general body colour translucent grayish white, the inner (dorsal) surface of the parapodia being bright green frommnumerous thin branches of the digestive gland. The dorsal surface of the rhinophores is a milky yellow except for the upper third which is dark purple. The edge of the parapodia also has a band of white or milky yellow which is broken by three evenly spaced raised points which are edged with purple. These raised points form three 'funnels' or 'chimneys' along the parapodia. The head and the outside of the parapodia have many scattered ovate black spots of varying size. There can be a black or dark purple ine along the anterior and posterior edges of the rhinophores. In some specimens there can be a red spot on either side of the mouth.
Kathe Jensen mentions that this species has anatomical similarities to the Mediterranean Elysia timida which feeds on Acetabularia. The bright green colour on the inside of the parapodia is also reminiscent of that species, as is the raised points along the parapodial edge. At present we know nothing about the biology of Elysia thompsoni. It would be interesting to know if it also feeds on Acetabularia. It grows to more than 10 mm in length.
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.
Jensen, K.R (1997) Sacoglossa (Mollusca,Opisthobranchia) from the Houtman Abrolhos Islands and central Western Australia. [In:] The Marine Flora and Fauna of the Houtman Abrolhos Islands, Western Australia. (Ed: Wells, F.E.) Western Australian Museum, Perth, 307-333.
Rudman, W.B., 2004 (December 22) Elysia thompsoni Jensen, 1993. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/elysthom
December 23, 2004
From: Jussi Evertsen
Good to see the Forum up and running again!
I want to expand the list of sacoglossans, and add here Elysia thompsoni Jensen, 1993, (many thanks to Kathe Jensen helping me identifying it). The specimen in the picture was collected at Rat Island, Houtman Abrolhos, Wstern Australia, July 21st this summer. We found at least a good 20 individuals around the jetty at 2-4 meters depth under dead coral blocks. Later we also found this species (two specimens) in Shark Bay at Eagle Bluff near Denham just near the shore at 1.5 meters depth.
It also showed active photoynthesis, and these results will hopefully be published in the Records of the Western Australian Museum soon.
Locality: Rat Island, Houtman Abrolhos Ids, Depth: 2-4 meters, Western Australia, Indian Ocean, Length: 15 mm, 21 July 2004
near shore, coral rubble and stones
Photographer: Marta Pola
firstname.lastname@example.orgEvertsen, J, 2004 (Dec 23) Elysia thompsoni from Houtman Abrolhos Ids, W. Australia . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12815
It's good to get another sacoglossan to add to the Forum, especially a solar-powered one. I look forward to reading more about it in your publication. It would be interesting to know if it feeds on Acetabularia, as it has many similarities to Elysia timida.