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

Order : Nudibranchia Suborder : Euctenidiacea Superfamily : Doridoidea Family : Chromodorididae Distribution : Western Indian Ocean. Maximal size : 40 mm Abundance : Seldom on the fore reef zone Species characteristics : Mantle ground color pale yellow to cream, with a border of reddish violet or magenta, and five parallel lines of the same color run down the dorsum.    Indistinct violet patches run between the violet lines of the dorsum form a network    The foot is yellow. It has a border of reddish violet, and two lines of same colour run along the side on each side.    The margins of the mantle overhang all the sides of the body    The gills and rhinophores are bright orange-red
	Showing species characteristics...	Photo Philippe Cao Van Reunion, "la pierre au prefet" at Saint Gilles, 20 m, 12 November 2006, size 30 mm

See more about : Sightening and mating periods

Remarks :

Identification confirmed by Bill Rudman and Nathalie Yonow

Bibliographic data :

The species name "maridadilus" is from the Swahili word for beautiful, "maridadi"
    The mantle is spatula-shaped, the anterior end rounded and a little wider than the rest of the mantle. There is a slight overlap of the mantle along the sides.
    Five dorsum lines description :
- The median line begins just behind the rhinophores and go back to the gills pocket
- A pair of lines on each side of the median line run from each rhinophore pocket to the posterior end of the dorsum. The inner one of each pair runs around the gills pocket joining the midline.
- A thick curve line runs between the rhinophores and a purple border around each of the rhinophores pockets and the gills pockets
    Foot lines description :
- The two reddish violet lines run along the side of the foot on each side, one in the middle another at the junction of the foot and the underside of the mantle.
- The two lines on each side join in the posterior midline to form a single line on the posterior part of the foot
    The gills are red-orange, simple, there are 12 in the holotype. They form a complete circle.
    It looks like Hypselodoris emma, but H. emma has only 3 longitudinal purple lines on the mantle, while H. maridadilus have 5 longitudinal lines.
    It looks that there are a pair of sibling species, one in the Indian Ocean (H. maridadilus ) and one in the western Pacific ( H. whitei ). Nathalie Yonow described a similar species H. centuculus from Maldives Island with white tips on the rhinophores (for Gosliner and Johnson (1999) it is a synonymous of H.whitei)

Material examined by Nathalie Yonow ( see reference/publications).

Four specimens collected from Pointe église paresseuse (Mauritius), 27 and 31 October 1985, size : 26, 31, 41 and 50 mm.

References :

Bill Rudman Sea slug site : Sea Slug Forum : Hypselodoris maridadilus
   Nudipixel Hypselodoris whitei

Publications :

Gosliner, T.M. & Johnson, R.F. (1999) Phylogeny of Hypselodoris with a review of the monophyletic clade of Indo-Pacific species, including descriptions of twelve new species. Zoological Journal of the Linnean Society, 125 : 1-114.
    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. (1977) Chromodorid opisthobranch Mollusca from East Africa and the tropical West Pacific. Zoological Journal of the Linnean Society, 61 : 351-397.
    Yonow, N. (1994) Opisthobranchs from the Maldive Islands, including descriptions of seven new species (Mollusca: Gastropoda). Revue fr. Aquariol., 20(4) : 97-130.

Other photos of Hypselodoris maridadilus :

Maurice Jay Reunion, In this over-exposure photo we clearly observed the pattern organisation of the five dorsal lines. - The median line begins just behind the rhinophores and go back to the gills pocket - A pair of lines on each side of the median line run from each rhinophore pocket to the posterior end of the dorsum. The inner one of each pair runs around the gills pocket joining the midline. - A thick curve line runs between the rhinophores and a purple border around each of the rhinophores pockets and the gills pockets

Florence Trentin Reunion, 16 November 2008 Two lines run along the side of the foot on each side, one in the middle (a) another at the junction of the foot and the underside of the mantle (b)    The gills and rhinophores are bright orange-red

Emmanuel Schubert Mayotte, 19 January 2011

Mauritius, Hypselodoris maridadilus, at Pointe Eglise, by Nathalie Yonow