Melibe engeli Risbec, 1937

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This species has been observed on Reunion, Mauritius and Madagascar Islands


Order : Nudibranchia
Suborder : Dexiarchia
Superfamily : Tritonioidea
Family : Tethydidae
Distribution : Indo West Pacific
Maximal size : 60 mm
Abundance : Seldom if ever on the rocky coast


Species characteristics :

They are white to pale yellow, extremely transparent, with the viscera visible through the body

The body surface has few to many conical papillae, tapering to acute or acuminate apices. There are scattered fine white dots or tubercles on or near the body surface, which are more numerous on the papillae

The cerata are tuberculate and have elongate papillae at the ends

The rhinophores have a flared sheath with a large flap bearing elongated processes on the margin

melibe viridis
Showing species characteristics...
Christophe Cadet
Reunion, Etang Salé, on the rocky coast, less 1 m, 5 December 2010, size : 60 mm

See more about : Sightening and mating periods

Remarks :

Identification confirmed by Nathalie Yonow and Vie Panyarachum
    Synonymous : (according Worms)
               - No other name

Bibliographic data :

The circular oral hood is small compared to the rest of the body.
            - The margin of the hood is entire in the majority of the specimens observed, although in some it is indented slightly, usually basally.
            - In all specimens there is an inner and an outer row of long, tapering, conical, tentacular papillae with recurving tips.
            - Some specimens exhibit up to 5 rows, most often near the basal margin. These rows are more or less equal in length, and have a visible axial fiber extending from the hood margin out to the tip, and a concentration of fine white spots.
    The rhinophores are sheathed and born within separated processes that arise from the dorsal surface of the oral hood. The sheaths are somewhat inflated and cylindrical with spreading circular margins that produce a flattened, leaf-like posterior process. There is a great deal of variation among specimens, but a “cockscomb” of 3–5 obtuse to acutely pointed papillations is typical present, creating an effect that resembles the outline of a typical cerata.
    There are 3–6 cerata on each side of the dorsal midline
            - The cerata are transparent, and the branches of the digestive gland within them are visible
            - The anteriormost left and right cerata are opposite, with the remaining cerata most often alternating
            - The cerata are inflated, and variable in outline, ranging from oval, saccate, or pyriform, to elongate and cylindrical
            - The surface may be smooth, or covered with low tubercles that give it a broadly warty look, or that may give the margins a lobed or undulating appearance
            - The distal margins range from plain and oval to papillately ornamented. The ornamentation may range from low obtuse papillae to one to three flattened processes bearing 3–6 elongate triangular pappilae in a “cockscomb” pattern
            - Gills may be present on the inner face at the base of each cerata
            - Specimens have been observed with few to many missing cerata, and with cerata in different stages of apparent regeneration and growth

 

The anus is located on the right side in the gap between the first and second anterior cerata, midway or slightly more proximal to the anteriormost cerata.
    The gonopore is well ventral to and on a line with or just anterior to the anteriormost right cerata. There are no papillae associated with the gonopore.
    Species of Melibe swim by folding the foot and flexing the body laterally
    Known to feed on plankton and small crustaceans. Species of Melibe feed on shrimps, crabs and other small crustacea which they catch by waving the inflated oral hood over the substrate like a metal detector. When the sensory papillae touch a crustacean the hood rapidly closes, trapping the prey inside where it is gradually manipulayed back to the "mouth" Species of Melibe lack a radula, prey remaining alive in the gut until killed by digestive juices
    It has a white dextrally spiralling egg ribbon
    Found on the algae Padina and Acanthophora on swallow reef flats of 1-5 m depth. Often occurs with Aplysia oculifera and Notarchus indicus
    Juveniles are very transparent indeed but darken with age.

References :

Bill Rudman Seaslug site : Sea Slug Forum : Melibe engeli
   Nudipixel Melibe rangii

Publications :

Gosliner, T.M. (1987) Review of the nudibranch genus Melibe with description of two new species. The Veliger, 29 : 400-414
    Gosliner, T. M. and. Smith, V. G. (2003). Systematic review and phylogenetic analysis of the Nudibranch genus Melibe (Opisthobranchia: Dendronotacea) with descriptions of three new species. Proceedings of the California Academy of Sciences, Vol 54, (18) : 302–355
    Risbec, J. (1937). Note préliminaire au sujet de nudibranches Néo-Calédoniens. Bulletin Muséum National d'Histoire Naturelle Paris, series 2,9 : 159-164.

Other photos of Melibe engeli :


Barbara Bini

Madagascar, Nosy bé, 22 m,
size : 30 mm


- The cerata are transparent, and the branches of the digestive gland (a) within them are visible

- The cerata are tuberculate (b) and have elongate papillae (c) at the ends

- The body surface has few to many conical papillae (d), tapering to acute or acuminate apices. There are scattered fine white dots

Christophe Cadet

Reunion, Etang Salé, on the rocky coast, less 1 m,
5 December 2010, size : 60 mm


Geoffrey Summers

Mauritius, Pointe d'Esny, less 1 m, 10 November 2014, size : 30 mm

 

The circular oral hood (a) is small compared to the rest of the body and to Melibe viridis

 


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