Placida tardyi

Placida tardyi   (Trinchese, 1873)

Placida tardyi, original artwork by Salvatore Trinchese (1879: Lam. XV, Fig. 1) by Webmaster

Class: Gastropoda  Cuvier, 1797
Subclass: Heterobranchia  J.E. Gray, 1840
Clade: Euthyneura  Spengel, 1881
Clade: Panpulmonata  Jörger et al., 2010
Clade: Sacoglossa  von Ihering, 1876
Superfamily: Limapontioidea  J.E. Gray, 1847
Family: Limapontiidae  J.E. Gray, 1847
Genus: Placida  Trinchese, 1877-79
Species: Placida tardyi   (Trinchese, 1873)


  • Laura tardy Trinchese, 1873

The specimens of this species can reach a size of about 15 mm. The body is elongated and slender. The base color of the body is yellowish or whitish, but it is masked by the numerous branches of the digestive gland, olive green, that darken the body in dorsal vision. These hepatic branches also branch out to the rhinophores, the anal peduncle, the head and the sides of the body. The cardiac area is coloured in white and has the shape of an elongated spot. There are also usually small brown scores and somewhat larger opaque white spots on the flanks of the body. The head is small. The rhinophores are long and thin, they are longitudinally grooved and have a reddish coloured pointed tip. The anal orifice is located in front of the cardiac area, at the end of a prominent papilla. The genital orifice is located right behind the right rhinophore and there is an elongated reddish stain from this point to the middle of the body side. There are numerous cerata on the back, which are arranged tightly; their shape is elongated and tappered. Within them the pale green digestive gland is visible forming a non-branched duct. There is a purple stain at the apex of each cerata with some white granulations clustered together right below. The foot is somewhat broad in front and the tappered tail is thin. The foot is yellowish with fine brown or reddish scores forming two coloured longitudinal bands (Trinchese, 1879: Lam XV, Figs 1 and 2). This species has been confused on several occasions with Placida viridis. Cervera et al. (1988) restablished the species Placida tardyi and clearly stated the differences with Placida viridis.

This species, like other sacoglossans, lives on green algae and marine phanerogams, where it is unnoticed because of its colouration. Gascoigne & Sordy (1980) reported its presence on the chlorophycean Bryopsis sp. and Schmekel & Portmann (1982) in meadows of Posidonia oceanica and Zostera. In both cases it was cited as Placida viridis. The last two authors indicate that it feeds on Bryopsis sp. and also describe its spawn as a flat ring or spiral with white eggs 40-60 microns in diameter.


  • Placida. From Latin “placeō”, please, satisfy. Also means placid, gentle, quiet, still, calm, mild, peaceful.
  • Tardyi. Possibly dedicated to the French admiral Louis Marie Françoise Tardy de Montravel, (1811-1864), who circumnavigated the world with Dumont d’Urville in 1837. Later he studied the South American coastal regions and also the Japanese and Sea of Okhotsk coasts. In 1854 he took posession of New Caledonia for France.

This species inhabits the western Mediterranean and nearby Atlantic areas. In the Mediterranean it has been reported in its type locality Genoa, Italy (Trinchese, 1873), in the port of Livorno, Italy (Gascoigne & Sordi, 1980) and in the gulf of Naples, Italy (Schmekel & Portmann, 1982). Outside the Mediterranean Sea it has only been observed in the coast of Cadiz, Spain (Cervera et al., 1988) and in Sagres, in southern Portugal (Calado et al., 2003).

Known georeferenced records of the species: Placida tardyi
: 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 observation probability for Placida tardyi based on our own records.

More pictures

    We have no (more) pictures for Placida tardyi


Further reading

Cite this article as:

Ballesteros, Manuel, Enric Madrenas, Miquel Pontes et al. (2012-2017) "Placida tardyi" in OPK-Opistobranquis, Published: 20/10/2014, Accessed: 18/12/2017 at (

In order to copy this cite or text fragments you must be a registered user.