Elysia thompsoni
Jensen, 1993

Order: SACOGLOSSA
Superfamily: ELYSIOIDEA
Family: Elysiidae

DISTRIBUTION

Known from Western Australia [Rottnest Id., Houtman Abrolhos Ids., Shark Bay].

PHOTO

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.
  

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