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This species has been observed on Reunion,  Mauritius Islands

Order : Nudibranchia Suborder : Euctenidiacea Superfamily : Doridoidea Family : Chromodorididae Distribution : Tropical Western Pacific and Indian Oceans. Maximal size : 30 mm Abundance : Frequently on the fore reef zone The light coat on the back is orange to purple on the side. It has thin white lines that can break in dashes. Purple spots are interspersed between these lines The ends of the body bordered with purple are speckled with white. The front part of the coat widens into a spatula. Important pattern variation : see below for more information
	Showing species characteristics...	Photo Alin Diringer Reunion, "Cap la Houssaye", Saint Paul, September 2008

Remarks :

We found in our country 4 species derived from Hypselodoris maculosa complex :  H. bertschi,  H. juniperae,  and  H. yarae

Identification confirmed by Bill Rudman
    Synonymes (d'après worms) :
          - Chromodoris decorata, Risbec, 1928
          - Chromodoris maculosa, (Pease, 1871)
          - Glossodoris decorata, (Risbec, 1928)
          - Hypselodoris decorata, (Risbec, 1928)

Bibliographic data :

The mantle is elongately oval, widening at the anterior end to give a spatulate appearance.
    The mantle overlap is very reduced, especially along the sides, and the foot extends some distance behind the posterior limit of the mantle.
    The animal is relatively high and narrow and the simple gills are arranged in a circle, open posteriorly, around the anus.

The colour pattern is complicated and very variable. To simplify the description a specimen from Tanzania, with what is probably the "simplest pattern", is described and other specimens are compared with that.

The background colour of the mantle is a pale milky orange-brown.
    Around the anterior of the mantle is a broad translucent pinkish-purple margin with scattered white and darker pinkish-purple spots.
    At the posterior end the margin is similarly coloured but the band is not as broad.
    From the level of the rhinophores back to the gill pocket, there is a broad orange band ( wider adjacent to the reddish-purple streaks) at the edge.
    On the inside edge of the orange band, there is a series of reddish-purple streaks, and between the reddish-purple streaks are a pair of white streaks.
    Running down the central part of the mantle are four narrow white lines.
    There are five small dark pinkish-purple spots down the midline between the gills and rhinophores.
    The rhinophore stalks are translucent white and the clubs are white with a broad orange band at the base and another just below the tip.
    The simple gills are translucent white with a deep orange line down the outer edge and an orange tip. The bottom half of each gill is translucent orange.
    The sides of the body and the foot are a translucent pinkish-purple with a colourless band at the edge.
    On the sides of the body there are white lines and streaks running parallel to the edge of the foot and some pinkish-purple spots.
    On the posterior part of the foot extending beyond the end of the mantle there are scattered white spots and around the inside edge of the colourless translucent margin is a row of elongate pinkish-purple streaks

Many variations exist in this species. For example in some specimen :

The white lines on the back are break into a series of short streaks
     There are the usual four white lines down the dorsum but further out on each side is another white line which thickens regularly along its length
     With the usual white lines down the dorsum, there are also some extra streaks
     There are many pinkish-purple spots on the mantle beetween the different white lines and also the posterior part of the foot
     The orange border along each side of the mantle is very pale except along its inside edge where it is a thin orange line which widens irregularly alongside a series of reddish spots.
     The orange margin and the band of red streaks along the inner edge of the orange margin tend to merge so that the colour gradually changes from orange at the outer edge to a wine-red on the inside edge. The width of this margin is irregular, widening to form reddish 'tongues' of colour into the cream central region where the red streaks merge with the original orange margin
     There is a bright orange border around the anterior end and around the posterior end but the region along either side is colourless.
     The background colour of the mantle is a pale cream.
     The mantle is translucent with a pinkish tinge, the cream-coloured viscera showing through over most of the mantle
     There can also be one, two or three orange bands on the rhinophore club.

References :

Bill Rudman Seaslug site : Sea Slug Forum : Hypselodoris maculosa
   Nudipixel Hypselodoris maculosa

Publications :

Guang-Yu, L, 1975. Opistobranchia from the intertidal zone of Xisha Island, Guangdong Province, China. Studia Marina Sinica, 10 : 141-154, pls 1, 2.
    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
    Pease, W.H. (1871). Descriptions of new species of nudibranchiate Mollusca inhabiting Polynesia. No. 2. American Journal of Conchology, 7(1) : 11-19, Pls 3-9.
    Risbec, J., 1928. Contribution à l'etude des nudibranches Néo-Calédoniens. Faune des Colonies Françaises, 2(1) : 328, pls 1-12.
    Rudman, W.B., 1984. The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: a review of the genera. Zoological Journal of the Linnean Society, 81 : 115-273.
    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 Hypselodoris maculosa :

Christophe Cadet Reunion, Etang salé lagoon, less 1 m, September 2010 H. maculosa and its spawn.

Maurice Jay Reunion, Rq : A specimen without any orange border... Variations visible in this specimen : There are the usual four white lines down the dorsum but further out on each side is another white line which thickens regularly along its length. There are also some extra streaks One orange band on the rhinophore

Sophie Darnis Reunion, "Kiosques" at Saint Leu, 15 m, 4 October 2007, size 15 mm Rq : Looks like Marina Poddubetskaia specimen from Mauritius. Variations visible in this specimen :               - Like the Tanzanian specimen, there is marginally a series of reddish-purple streaks, and between the reddish-purple streaks are a pair of white streaks.               - One orange band on the rhinophore

Sophie Darnis Reunion, "Pain de Sucre" at Boucan Canot, 16 m, 26 November 2006, size 15-18 mm Rq : Looks like M Jay specimen by with an orange marginal band between the rhinophores and the gills Variations visible in this specimen :               - There are the usual four white lines down the dorsum but further out on each side is another white line which thickens regularly along its length.               - One orange band on the rhinophore

Sophie Darnis Reunion, "Cirque des Aigrettes" at Saint Gilles, 22m, 18 May 2008, size : 20 mm Rq : The orange margin is present all around the mantle...             Two orange bands on the rhinophore May be H. maculosa or H. yarae this specimen have H. yare and H. maculosa caracteristics... Variations visible in this specimen : There are many pinkish-purple spots on the mantle beetween the different white lines The orange margin and the band of red streaks along the inner edge of the orange margin tend to merge so that the colour gradually changes from orange at the outer edge to a wine-red on the inside edge. The width of this margin is irregular, widening to form reddish 'tongues' of colour into the cream central region where the red streaks merge with the original orange margin

Maurice Jay Réunion, May be H. maculosa or H. yarae this specimen have H. yare and H. maculosa caracteristics...

Mauritius, Hypselodoris maculosa, at Pereybere, by Marina Poddubetskaia

Reunion, Hypselodoris maculosa hidden in a hole, at Saint Leu, by Eva Fontaine

Reunion, H. maculosa with numerous longitudinal white lines, at Etang Salé, by Philibert Bidgrain