Favorinus japonicus    Baba, 1949

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This species has been observed on Reunion, Mayotte and Seychelles Islands


Order : Nudibranchia
Suborder : Dexiarchia
Superfamily : Aeolidioidea
Family : Facelinidae
Distribution : Tropical western Pacific and Indian Oceans
Maximal size : 17 mm
Abundance : Seldom on the rocky coast


Species characteristics :

The body is translucent white to green with typical opaque white pattern.

Rhinophores, conical with two or threee prominent bulbous swellings are translucent white

The nodulose cerata papillate, are slightly recurved toward central body axis. They are light brown, pink, white, or green.

Favorinus japonicus
Showing species characteristics...

Photo Philibert Bidgrain
Reunion, Etang salé on the rocky coast, under a rock, 7 March 2007, size : 15-18 mm

See more about : Sightening and mating periods
   See more about : Favorinus japonicus variability in Southwest Indian ocean

Remarks :

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

Bibliographic data :

Oral tentacles elongate and sharply pointed. They are translucent white from middle to apex
    Anterior foot corners elongate and tentacular
    Cerata in five pairs of horseshoe-shaped arches.
    Gonopore ventral to cerata of first horseshoe, and anus within second horseshoe.
    These aeolids feed on the egg masses of various opisthobranchs, such as Aplysia Juliana, A. dactylomela, Dolabrifera dolabrifera, Melibe pilosa, Hexabranchus sanguineus, and Pleurobranchus semperi. Because a duct of their gut extends up into each of the cerata on their backs, they change colour depending on the colour of the eggs they are eating.

References :

Bill Rudman Seaslug site : Sea Slug Forum : Favorinus japonicus
    Nudipixel Favorinus japonicus

Publications :

Baba, K. (1949). Opisthobranchia of Sagami Bay collected by His Majesty The Emperor of Japan . Tokyo , p. 1-194, pls. 1-50

Other photos of Favorinus japonicus :


Philibert Bidgrain

These aeolids feed on the egg masses of various opisthobranchs

Reunion, Etang salé on a rocky coast
         - Right : Two specimens under a rock, 22 February 2006, size 8 mm.
         - Below : Under a rock, 12 February 2006, size 10 mm.


Philibert Bidgrain
Reunion
, Etang salé on a rocky coast, under a rock with numerous Dolabrifera dolabrifera, 31 01 2007, size 12-15 mm.


Philibert Bidgrain

Reunion, Etang salé on a rocky coast, under a rock, 12 February 2006, size 10 mm.

 

This animal shows some variation from most other Favorinus japonicus in having extremely nodulose cerata with cherry red tips. (like a specimen found in Heron Island by Julie Marshall, 2000)

A coloured duct of the digestive gland is visible in each cerata.


Sully Bachel

Reunion, Maison verte, Saint Leu, 14 March 2010, size 10-12 mm.

These aeolids feed on the egg masses of various opisthobranchs, such as Aplysia Juliana, A. dactylomela, Dolabrifera dolabrifera, Melibe pilosa, Hexabranchus sanguineus, and Pleurobranchus semperi.

Because a duct of their gut extends up into each of the cerata on their backs, they change colour depending on the colour of the eggs they are eating.


Philibert Bidgrain

Reunion, Etang salé on a rocky coast, under a rock, 5 November 2009, size 10 mm.

2 specimens found under a rock beside an egg masses...


Philibert Bidgrain

Mayotte, Mtsanga Guini, less 1 m, 3 August 2010, size : 6-8 mm

Found on a orange spawn looks like Asteronotus cespitosus spawn...

A pale orange-pink coloration

Cerata in regeneration (a)


 More photos from Indian Ocean

See more about : Favorinus japonicus variability in Southwest Indian ocean

Reunion, Favorinus japonicus with Dolabrifera dolabrifera, at Etang salé, by Philibert Bidgrain

Mayotte, pale orange Favorinus japonicus in a white spawn, at Sakouli, by Matthias Deuss  

Reunion, a white Favorinus japonicus, at La Saline, by Philibert Bidgrain  

Reunion, Favorinus japonicus in Hexabranchus sanguineus spawn, at Saint Gilles, by Sully Bachel 

Mayottte, a white Favorinus japonicus, at Sada, by Philibert Bidgrain  

Seychelles, Favorinus japonicus, at Mahé, by Christophe Mason-Parker