Elysia rufescens (Pease, 1871)

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This species has been observed on Reunion Island

Order : Sacoglossa
Superfamily : Plakobranchoidea
Family : Plakobranchidae
Distribution : Known from Tahiti, Hawaii, Guam, South Africa and now Reunion Island
Maximal size : 60 mm
Abundance : From time to time on the reef flat zone and on the rocky coast

Species characteristics :

Dark red maculated with spots of creamy green which impart a reticulated appearance to the animal; parapodia margined with orange and purple.

Rhinophores long and slender, directed anteriorly, dark red tipped with purple.

Elysia rufescens
Showing species characteristics...

Photo Hugues Flodrops
Etang salé on a rocky coast, 0.5 m,
27 December 2007, size : 50 mm

See more about : Sightening and mating periods
   See more about : Elysia rufescens variability in Southwest Indian ocean

Remarks :

Identification confirmed by Kathe Jensen and Bill Rudman

Bibliographic data :

E. rufescens, has been rarely reported from the western side of the Indian Ocean .Terry Gosliner's report of a single animal from the Indian Ocean coast of South Africa (Gosliner, 1987).
    The animals are usually found on the sides of rocks in shallow waters shoreward of fringing reefs where they crawl over assemblages of algae.
    In Hawaii, E. rufescens eats Bryopsis pennata and, from limited collecting experience, is rarely found very far away from it. They have found Bryopsis plastids in the digestive cells of E. rufescens.
    According : Department of Chemistry, University of Hawaii at Manoa, Honolulu 96822 , USA ( 21 November 2001).
                  # Sacoglossans are a group of opisthobranch mollusks that have been the source of numerous secondary metabolites, there are few examples where a defensive ecological role for these compounds has been demonstrated experimentally.
                  # Bryopsis sp. produces kahalalide F, a major depsipeptide that is accumulated by the sacoglossan. They show that kahalalide F protects both Brvopsis sp. and E. rufescens from fish predation as indicated by the deterrent properties of their extracts at naturally occurring concentrations.
    Kahalalide F, a novel marine-derived anti-tumour agent isolated from the sea slug Elysia rufescens displays both in vitro and in vivo anti-tumor activity in various solid tumor models including breast, colon, non-small cell lung, and in particular prostate cancer. Kahalalide F is currently undergoing Phase II clinical trials in various solid tumours: melanoma, non-small cell lung cancer and hepatocellular carcinoma.

References :

Bill Rudman Seaslug site : Sea Slug Forum : Elysia rufescens
   Nudipixel Elysia rufescens

Publications :

Baba, K (1957) The species of the genus Elysia from Japan . Publications of the Seto Marine Biological Laboratory, 6 : 69-74
    Jensen, K.R. (2007). Biogeography of the Sacoglossa (Mollusca, Opisthobranchia). Bonner Zoologische Beiträge. 55: 255281
    Kay, E.A. (1979) Hawaiian Marine Shells Bishop Museum Special Publication 64(4). Bishop Museum Press: Honolulu . p454
    Pease, W.H. (1871). Descriptions of Nudibranchiate Mollusca inhabiting Polynesia . American Journal of Conchology, 6(4) : 299-305

Other photos of Elysia rufescens :


Original illustrations from Pease, 1871

Paintings by Andrew Garrett.

Pterogasteron rufescens Pease, 1871.A copy of the figs Plate 22, figs 1a,b,c

It was 1.25 inches long. Found at Tahiti.

Philibert Bidgrain

Trois bassins lagoon, less 1 m, 20 May 2010, size : 20 mm

The most obvious characteristic distinguishing sacoglossa (externally) from other nudibranchs are the two rolled rhinophores (a) on the head.



Photo Hugues Flodrops

Etang salé on a rocky coast, less 1 m, 30 January 2007, size : 40 mm

Eating algae, just before the sunshine ?

According Bill Rudman : "I can't  be sure it is feeding in your photo, but Bryopsis, which it is reported to feed on, is often present as fine green filaments which are hard to see individually. "

Philibert Bidgrain

Etang Salé lagoon, less 1 m, 3 February 2007, size : 25-30 mm

We observe several specimens of this species with E. ornata and E. sp1 in the lagoon during this period.

Parapodia margin with orange and purple is very pale in this specimen

E. rufescens spawning : a spiral coiled white ruban



Philibert Bidgrain

Etang Salé lagoon, less 1 m, 3 February 2007, size : 15-18 mm

A small specimen with the dark red body maculated with spots of creamy green.

Philibert Bidgrain

Kelonia center, Saint Leu, 20 March 2010, size : 15 mm

A half turn...

 More photos from Indian Ocean

See more about : Elysia rufescens variability in Southwest Indian ocean
   Reunion, three Elysia species in the same area, at Etang salé, by Philibert Bidgrain
   Reunion, friendly meeting between two Elysia species, at Etang salé, by Philibert Bidgrain
   Reunion, Elysia rufescens in Kelonia center, at Saint Leu, by Lucie Maillot
   Reunion, Elysia rufescens with orange parapodia margin, at Saint Leu, by Stephane Ciccione 
   Reunion, Elysia rufescens, at Etang salé, by Florence Trentin  
   Reunion, head detail of Elysia rufescens, at Etang salé, by Christophe Cadet  
   Reunion, juvenile of Elysia rufescens with dark red body, at La saline, by Christophe Cadet 
   Reunion, Elysia rufescens in kelonia center, at Saint Leu, by Philibert Bidgrain