Ercolania coerulea Trinchese, 1892

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This species has been observed on Reunion Island

Order : Sacoglossa
Superfamily : Limapontioidea
Family : Limapontiidae
Distribution : Originally described from the Mediterranean, it is also observed in Caribbean, and Indo-West Pacific
Maximal size : 14 mm
Abundance : Seldom if ever on the reef flat zone and the rocky coast

Species characteristics :

The animal is translucent to transparent with the branching ducts of the green or green-brown digestive gland showing through the body wall, rhinophores and cerata.

Presence of opaque white clustered on the tips of the rhinophores and opaque white spots on the cerata (most dense at the tips of the cerata)

The rhinophores are simple, cylindrical

ercolania coerulea
Showing species characteristics...

Photo Christophe Cadet
Reunion, Etang salé on the rocky coast, less 1 m, 12 February 2010, size : 4-5 mm

See more about : Sightening and mating periods

Remarks :

Identification confirmed by Kathe Jensen
    Schmekel & Portmann (1982) give a detailed description of the colour of "Mediterranean form". They describe opaque white clustered on the tips of the rhinophores and the pericardium, and opaque white spots on the cerata arranged in a characteristic pattern, consisting of a white tip to the cerata and a white line running from the tip down the sides of the ceras. They also describe a blue 'blotch' on the dorsal surface of each ceras, and smaller blue spots scattered elsewhere on the cerata. They report that it feeds on the green alga Valonia. It grows to about 14 mm in length
    The "Indo-West Pacific form" feeds on Dictyosphaeria, and lacks the blue spots on the cerata.
    Synonymous : (according Worms)
               - Ercolania costai Pruvot-Fol, 1951                         - Stiliger cricetus Er. Marcus & Ev. Marcus, 1970

Bibliographic data :

A branch of the digestive gland enters the rhinophores, where it also forms a fine network almost to the tips of the rhinophores.
    The eyes are relatively large, located at the bases of the rhinophores
    The anterior part of the head forms a sort of veil surrounding the almost circular mouth area
    The cerata are very numerous and easily autotomized when the animal is disturbed
    There is a conspicuous flat tail devoid of cerata
    In the live specimen a brownish sphere was visible through the epidermis on the anterior right side of the neck, between the posteriormost branches of the digestive gland in the head
    The species is very camouflaged when on its food, Dictyosphaeria, and usually it is the presence of the delicate, transparent egg masses with numerous small, white eggs arranged in a lace-like pattern, which first attract the attention. In Reunion Island we found Dictyosphaeria cavernosa (Silva, C., P. Basson & R. Moe (1996))

References :

Bill Rudman Seaslug site : Sea Slug Forum : Ercolania coerulea

Publications :

Jensen, K. R. (1985) Annotated checklist of Hong Kong Ascoglossa (Mollusca: Opisthobranchia), with descriptions of four new species: Proceedings of the 2nd International Workshop on the Malacofauna of Hong Kong and Southern China, Hong Kong, 1983 . (Eds B. Morton, D. Dudgeon, B. Morton, and D. Dudgeon.) pp. 77-107. (Hong Kong University Press: Hong Kong.)
    Jensen, K.R. (1993) Sacoglossa (Mollusca, Opisthobranchia) from Rottnest Island and central Western Australia. In: Proceedings of the 5th International marine Biological Workshop: The marine Flora and Fauna of Rottnest Island, Western Australia . (Eds: Wells,FE; Walker,DI; Kirkman,H; Lethbridge,R) Western Australian Museum, Perth, 207-253
    Schmekel, L. and Portmann, A. (1982) Opisthobranchia des Mittelmeeres, Nudibranchia und Saccoglossa . Fauna e Flora del Golfo di Napoli, 40. Monografia della Stazione Zoologica di Napoli : 1-410.
    Silva, C., P. Basson & R. Moe (1996). Catalogue of the Benthic Marine Algae of the Indian Ocean. Volume 79 of University of California Publications in Botany (ISBN 0-520-09810-2)
    Trinchese, S. (1892) Nuovi ascoglossi del golfo di Napoli. Rend. Accad. Sci. Fis. May. Soc. R. Napoli, 7: 154-155

Other photos of Ercolania coerulea :

Philibert Bidgrain

Reunion, La Saline lagoon, less 1 m, 11 March 2010, size : 6-8 mm


Two specimens present on its favourite alga :

Dictyosphaeria cavernosa




Christophe Cadet

Reunion, Etang salé on the rocky coast, less 1 m, 12 February 2010, size : 4-5 mm

The second specimen found by Christophe Cadet crawling on the substrate, seeking her favorite alga ...


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