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

Order : Cephalaspidea Superfamily : Philinoidea Family : Aglajidae Distribution : Tropical Indo-West Pacific Maximal size : 50 mm Abundance : From time to time on the reef flat zone Species characteristics : The background coloration is dark blue-black all over except for the margins of the parapodia and caudal lobes which have distinctive, thin, vivid blue lines. This species has a round rather than truncate anterior end of the body. It has a high rounded bump on the head. The posterior shield ends in two rounded lobes very short compared to Chelidonura, the left caudal lobe is slightly longer than the right lobe.
	Showing species characteristics...	Photo Philibert Bidgrain Reunion, "Kelonia center", at Saint Leu, 28 November 2006, size : 50-55 mm

See more about : Sightening and mating periods
   See more about : Philinopsis gardineri variability in Southwest Indian ocean

Remarks :

Identification confirmed by Bill Rudman

Bibliographic data :

Many Reunion Island's specimens present a particular pattern of coloration with yellow marks, usually it is a uniform dark blue-black species. One little specimen is very pale in coloration.
    The body is elongate-oval, the headshield being between two-fifths and one-half the body length.
            - The posterior corners of the headshield are rounded whereas in the posterior midline the edge extends into a rounded point, this pointed crest being raised while the animal is moving.
            - The posterior shield is rounded anteriorly and extends back just beyond the end of the foot. At the back of the shield, small flaps extending posteriorly from each side fold down to partially enclose the posterior end of the mantle cavity.
            - The parapodia, lateral extensions of the foot, are large and fold up, covering the sides of the headshield and posterior shield
    The Aglajidae are all carnivorous hunters. The species of the genus Philinopsis can be divided into two groups.
            -"Philinopsis taronga group" (ex : P cyanea), have a large partially eversible buccal bulb. They use the buccal bulb to catch the bubble shells and other opisthobranchs.
            -In "Philinopsis pilsbryi group" (ex P gardineri), the buccal bulb is a long muscular tube. It is possible that they use the buccal bulb as a long eversible tube which can catch prey (worms?) in narrow burrows or crevices. Species with this foregut are usually quite easy to identify in the living animal as the folds of the tube form a rounded central crest on the head
    Species of Philinopsis are usually found burrowing in sand or sandy mud.
    The shell contains a narrow calcareous portion and a large, anteriorly directed, membranous or weakly calcified wing
    P. gardineri is very similar in colour to the related Chelidonura varians from which it can be easily separated by the long and inegual pointed posterior tails present in Chelidonura.
    P. gardineri is very similar in colour to some coloration pattern of P. cyanea. But P. cyanea has the body anterior end truncated, while P. gardineri has a round-headed with a high rounded bump on the head.

References :

Bill Rudman Seaslug site : Sea Slug Forum : Philinopsis gardineri
   Nudipixel Philinopsis gardineri

Publications :

Rudman,W.B., 1972. A comparative study of the genus Philinopsis Pease, 1860 (Aglajidae, Opisthobranchia). Pacific Science, 26 : 381-399.
    Rudman,W.B., 1972. Structure and functioning of the gut in the Bullomorpha (Opisthobranchia). Journal of Natural History, 6 : 547-560.
    Gosliner,T. M., 1980. Systematics and phylogeny of the Aglajidae (Opistobranchia : Mollusca). Zoological Journal of the Linnean Society, 68 : 325-360

Other photos of Philinopsis gardineri :

Philibert Bidgrain. Some Reunion Island's specimens present a particular pattern of coloration with yellow marks, usually it is a uniform dark blue-black species. Reunion, Two specimens found in a pool at "Kélonia center" a Marine Turtle Center in Saint Leu.

Philibert Bidgrain Reunion, "Kélonia center" a Marine Turtle Center in Saint Leu 15 December 2006, size : 40-45 mm I found on this pool with this white egg masses only specimen of P. gardineri...

Matthias Deuss Mayotte, récif d'Handréma, 2 m, 25 December 2009, size : 60 mm Like some Reunion's specimen, this present a particular pattern of coloration with yellow marks.

See more about : Philinopsis gardineri variability in Southwest Indian ocean

Reunion, Philinopsis gardineri, at Mare de baramine, by Maurice Jay

Reunion, a small pale Philinopsis gardineri, at Saint Pierre, by Alain Barrère

Reunion, Philinopsis gardineri with yellow marks, at Etang salé, by Christophe Cadet  

Rodrigues, Philinopsis gardineri without yellow marks, at Saint François, by Thierry Peres