Jorunna parva ( Baba, 1938 )

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This species has been observed on Reunion and Mayotte Islands


Order : Nudibranchia
Suborder : Euctenidiacea
Superfamily : Doridoidea
Family : Discodorididae
Distribution : Japan, Philippines, Mer Rouge, Tanzania, Papua New Guinea, Seychelles and now Réunion
Maximal size : max 21 mm
Abundance : Seldom if ever ...

Species characteristics :

The background coloration is yellow-orange to dark brown with scattered black caryophyllidia

Foot with a dark brown line on middle part of visible portion, with dark brown spots along edges clearly visibly when the animal moves

The rhinophores have a black club with light yellow base.

jorunna parva
Showing species characteristics...

Photo Olivier Aubrespin
Reunion, Saint Pierre lagoon, 17 January 2005, 20 mm

See more about : Sightening and mating periods

Remarks :

Identification confirmed by Nathalie Yonow
    Our specimens have base of rhinophore rachis whitish with dark brown clubs, and whitish gills with dark brown rachises.
    Synonymous : (according Worms)
          - Thordisa parva, Baba, 1938

Bibliographic data :

    Like Rostanga, species of Jorunna have a very 'bristly' back as their mantle is covered in caryophyllidia ( about 250 m in length) . Caryophyllidia are spiculate papillae (small tubercles bearing a crown of pointed spicules) found in a number of dorid genera.
    Caryophyllidia of different shapes and sizes, the larger ones sparsely distributed between the smaller ones. Larger caryophyllidia leaf-like in shape, homogeneously distributed, the rest generally smaller, elongated. Higher caryophyllidia dark brown in colour, resembling dark spots in mantle
    The colour pattern is variable.
      - Most specimens with a dark yellow background colour becoming lighter in areas close to rhinophores and gill. (like our specimen)
      - Other specimens with a dark brown colour in central part of dorsum, becoming dark yellow towards edges of mantle (forming a V-shape in area behind rhinophores). Light yellow colour following, becoming darker again towards front part of rhinophores .
     -  In some cases it can have a white background colour, and sometimes the scattered black caryophyllidia are replaced by prominent black patches, each patches being made up of a group of black caryophyllidia.
    Six or seven short bipinnate branchial leaves and rhinophores with 14-15 lamellae.
    In some specimens, base of rhinophore rachis light yellow with dark brown clubs, base of gill light yellow with dark brown tips. Other specimens with rhinophores with dark brown rachises containing light yellow clubs and light yellow gills with dark brown rachises.
    Large white mantle glands around mantle
    This species closely resembles to Jorunna pardus from California.

References :

Bill Rudman Seaslug site : Sea Slug Forum : Jorunna parva
   Nudipixel Jorunna parva

Publications :

Baba, K. (1938) Opisthobranchia of Kii, Middle Japan. Journal of the Dept of Agriculture, Kyushu Imperial University, 6(1) : 1-19.
   
Yolanda E. Camacho-Garcia and Terrence M. Gosliner, (2008), Systematic revision of Jorunna Bergh, 1876 (Nudibranchia, Discodorididae) with a morphhological phylogenetic analysis Journal of Molluscan Studies (2008) 74: 143181

Other photos of Jorunna parva :


 

Olivier Aubrespin

The same that the upper photo

Reunion, Saint Pierre lagoon, 17 January 2005, 20 mm

Presence of the caracteristic median black band on the posterior tip of the foot.

Most specimens with a dark yellow background colour becoming lighter in areas close to rhinophores and gill. (like our specimen)

jorunna sp2


Monika Bachel

Reunion, La Possession, 6 m, 1 November 2009, size : 10 mm

This specimen also have base of rhinophore rachis whitish with dark brown clubs, and whitish gills with dark brown rachises.


 

Sully Bachel

Reunion, Sainte Suzanne, 6 m, 9 November 2009, size : 10-12 mm

Foot with a dark brown line on middle part of visible portion


Christophe Cadet

Reunion, Etang salé lagoon, less 1 m, 27 December 2009, size : 5 mm

On this juvenile, the charactéristic brown line on middle part of the foot, with dark brown spots along edges aren't visibly


Rachel Lebatard

Reunion, Saint Pierre lagoon, less 1 m, 5 January 2011, size : 10 mm

Caryophyllidia of different shapes and sizes, the larger ones sparsely distributed between the smaller ones. Higher caryophyllidia dark brown in colour (a), resembling dark spots in mantle


More photos from Indian Ocean

Mayotte, Jorunna parva, at Pamandzi, by Norbert Verneau