Mexichromis pusilla (Bergh, 1874)

Version française...

This species has been observed on Reunion, Mayotte, Madagascar and Seychelles Island


Order : Nudibranchia
Suborder : Euctenidiacea
Superfamily : Doridoidea
Family : Chromodorididae
Distribution : Tropical Indo-West Pacific.
Maximal size : 20 mm
Abundance : Seldom on the rocky coastand the reef flat zone


Species characteristics :

The mantle is a pale pink to red with a broad cream-white or yellowish band at the edge.
   There is an elongated white streak in the midline between the rhinophores and another in front of the gills.
    Around the anterior and posterior ends and twice down each side of the mantle, the inside edge of creamy yellow border is excavated out and replaced by a washy purple patch.
    The gills and rhinophores are tinged with orange.

Durvilledoris pusilla
Showing species characteristics...
Photo Philibert Bidgrain
Reunion, Etang salé on a rocky coast, 8 November 2005, size 20 mm

See more about : Sightening and mating periods

Remarks :

Identification confirmed by Hsini Lin and Bill Rudman
    Several specimens observed in our island have a particular coloration on the gills, the upper half of the seven gills with a purple coloration like in Mexichromis lemniscata.
    Synonymous : (according Worms)
          - Chromodoris pusilla, Bergh, 1874
          - Durvilledoris pusilla, (Bergh, 1874)

Bibliographic data :

Two photographs from Mr S. Johnson of specimens collected at Enewetak Atoll have slightly different background colours but both have the pair of tongue-like extensions on each side. One specimen is a light violet-purple with a cream border and orange rhinophore clubs and the watery orange gills are tipped with violet (P. Bidgrain 8 December 2004). In the other specimen the background colour is red ( P. Bidgrain, 16 mai 2006) and the border is a cream-yellow colour. Similar variation from reddish-pink to purple is found in Verconia purpurea and Mexichromis similaris
    M. pusilla can usually be separated from the other two similar appearing species (Verconia varians and Verconia norba) by its two pairs of purple lobes which uniformly extend to the lateral margins of the dorsal surface of mantle (notum).
    The mantle is elongated, overlapping the foot all around except posteriorly.
    The gills are simple and form a circle, open posteriorly around the anus.

References :

Bill Rudman Seaslug site : Sea Slug Forum : Durvilledoris pusilla
   Nudipixel Durvilledoris pusilla

Publications :

Johnson R.F. & Gosliner T.M. (2012) Traditional taxonomic groupings mask evolutionary history: A molecular phylogeny and new classification of the chromodorid nudibranchs. PLoS ONE 7(4): e33479
    Rudman,W. B. (1986), The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Noumea purpurea and Chromodoris decora colour groups. Zoological Journal of the Linnean Society 86(4) : 309-353.

Other photos of Mexichromis pusilla :


Philibert Bidgrain

Reunion, Etang salé les bains lagoon under a rock,

8 December 2004, size : 10 mm

Upper half of the seven gills with a strange purple coloration, we needs other photos to confirm this observation

These variation in gill's coloration was observed by S. Johnson on specimens collected at Enewetak Atoll.

Durlilledoris pusilla P.Bidgrain


Philibert Bidgrain

 

Reunion, Etang salé les bains on a rocky coast, 16 May 2006, size 10-12 mm.

In this other specimen the background colour is red like in S. Johnson specimens collected at Enewetak Atoll.


Hugues Flodrops

Reunion, Etang salé, on the rocky coast, less 1 m, 31 December 2008, size : 18mm

Upper half of the gills with a strange purple coloration, we needs other photos to confirm this observation

These variation in gill's coloration was observed by S. Johnson on specimens collected at Enewetak Atoll.

 


Olivier Police

Mayotte, Pointe des Badamiers, on the reef flat zone, 1 m, 3 January 2010, size : 10 mm

A specimen with only 6 gills

And a cream-white border on the foot...

 


Philibert Bidgrain

Réunion, Etang salé on the rocky coast, less 1 m, 9 December 2009, size : 8 mm

A specimen with a lateral abnormal overgrowth at the gill level

Always a Reunion 's specimen with upper half of the gills with a strange purple coloration...


In Nudibranches of Seychelles by Christophe Mason-Parker

Observed at Beau Vallon, Mahé, size : 15 mm

Under the name Noumea varians (misidentification...)

 

Available online on Archipelago Island

 


 More photos from Indian Ocean

Reunion, Mexichromis pusilla, at Saint Paul, by Maurice Jay

Reunion, Mexichromis pusilla, at Etang salé, by Philibert Bidgrain

Mayotte, Mexichromis pusilla with red mantle, at Passe en S, by Matthias Deuss

Madagascar, Mexichromis pusilla, at Nosy Bé, by Alain-Benoît Rassat