Bosellia mimetica

Bosellia mimetica (Trinchese, 1891)

Bosellia mimetica by Enric Madrenas




































Bosellia mimetica  Trinchese, 1891

 Classification according to Bouchet et al. (2017)
Taxonomic source: World Register of Marine Species (AphiaID: 138851).
When fully extended, this animals are elongated and can reach up to about 8 mm in length, however when they are at rest their contour can be almost circular and have nearly half the size. The overall color is dark green. Moving animals clearly differentiate the head region, which has a rounded oral lobe, and the rest of the body, both regions separated by a kind of groove. The rhinophores are short and auriculate and their eyes are located at the base, in the center of a small depigmented area. The back of the animal lacks any kind of expansions but its anterior cardiac region protrudes slightly. The general color of the body and the head region is light green but this color is dotted by numerous dark green spots that provide a darker tone to the whole animal. The rhinophores are usually colored lighter than the rest of the body. The back can be sometimes decorated by small crimson and white spots on the margins of the body formed by clusters of white grains.

This species is closely associated with the chlorophycean algae Halimeda tuna that it feeds on, and onto which it is commonly found. The sacoglossan “steals” chloroplasts from the algae and incorporates them into its tissues where they are still functional for a while, photosynthesizing organic molecules that are used by the animal. The abundance of chloroplasts in Bosellia mimetica‘s tissues makes it acquire a green shade almost identical to the alga Halimeda tuna it feeds on, rendering a perfect camouflage, and the byproducts photosynthethised by chloroplasts in the sacoglossan serve as food. The spawn of this species has the form of a tight spiral cord with numerous laps and white eggs. The eggs are deposited on the same alga Halimeda tuna or on the also chlorophycean Flabellia petiolata.


  • Mimetica. Derived from Latín “mimus”, meaning mime, pantomime, clown, but also imitator. Related to its ability to blend in with the substrate.

This species is very common throughout the western Mediterranean but it is also present in its eastern shores as Greece and Croatia. This species has also been cited in the tropical western Atlantic coast from Florida to northern Brazil. In Catalonia it is present all along the coastline, always associated with Halimeda tuna algae.

Known georeferenced records of the species: Bosellia mimetica
: GROC 2010-2011
: Enric Madrenas
: João Pedro Silva
: Bernard Picton
: Manuel Ballesteros.
: M@re Nostrum
: Altres fonts
: Marine Regions


    Western Mediterranean: ☆☆☆☆☆
    Eastern Mediterranean: ☆☆☆☆☆
    Atlantic Ocean: ☆☆☆☆☆

This chart displays the monthly observation probability for Bosellia mimetica based on our own records.

More pictures


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Further reading

Cite this article as:

Ballesteros, M., Madrenas, E. & Pontes, M. (2023) "Bosellia mimetica" in OPK-Opistobranquis. Published: 17/05/2012. Accessed: 02/03/2024. Available at (

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