Favorinus tsuruganus    Baba & Abe, 1964
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This species has been observed on Reunion Island

Order : Nudibranchia
Suborder : Dexiarchia
Superfamily : Aeolidioidea
Family : Facelinidae
Distribution : Japan, Eastern Australia and New Caledonia
Maximal size : 25 mm

Species characteristics :

Body and oral tentacles are opaque white.

Ceratal wall translucent, but digestive gland duct is orange with a black tip.

The rhinophores are black and have three 'cup-shaped' or 'collar-like' swellings.


favorinus tsuruganus M.Jay
Showing species characteristics...

Photo Monika Bachel, Reunion Saint Denis, Le Barachois, 14 m, 29 March 2014, size : 10 mm

See more about : Sightening and mating periods

Remarks :

Identification confirmed by Bill Rudman
    Synonymous : (according Worms)
               - No other name

Bibliographic data :

Species of Favorinus eat other opisthobranch eggs. In most species (as Favorinus japonicus), the colour of the ceratal digestive gland is dependent on the colour of the eggs they are eating. It can change colour from pale yellow to quite a deep orange-red depending on the colour of the eggs it has been eating. In Favorinus tsuruganus however, the cerata are consistently yellow-orange with a black tip.
    Species of Favorinus , which feed on the eggs of other opisthobranchs, are often found away from their food because they need to move around to find new egg ribbons.
   But on large egg masses, species of Favorinus can live their whole life cycle on the one egg ribbon, even to the extent of laying their own egg ribbon on the ribbon they are eating
    Favorinus tsuruganus appears to be a species that will eat a wide variety of opisthobranch eggs.While in tropical waters Favorinus tsuruganus is often found on the eggs of Hexabranchus , there is no good study to show that it doesn't also feed on less conspicuous egg ribbons.
    There is similarities with Favorinus cf mirabilis but in F. cf mirabilis the body and the oral tentacles are orange and there is a white to pale orange tip to the cerata. Also the rhinophores have numerous leaflets, rather than the three "cup-shaped swellings" found in F. tsuruganus

References :

Bill Rudman Seaslug site : Sea Slug Forum : Favorinus tsuruganus

Publications :

Baba, K. & Abe, T. (1964) Record of Favorinus tsuruganus n. sp., from Tsuruga Bay, Japan (Nudibranchia - Eolidoidea). Publications of the Seto Marine Biological Laboratory, 12(2) : 163-164.
    Baba, K. & Abe, T. (1975) Comments on further specimens of Favorinus tsuruganus Baba & Abe from Echizen-cho near Tsuruga Bay, Japan (Nudibranchia: Eolidoidea: Favorinidae). Publications of the Seto Marine Biological Laboratory, 22(1-4) : 117-120

Other photos of Favorinus tsuruganus :

Maurice Jay


Body and oral tentacles are opaque white.

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