Placida cremoniana

Placida cremoniana (Trinchese, 1892)

Placida cremoniana @ Punta del Plom, Begur (Spain) 20080614 by Miquel Pontes

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 cremoniana (Trinchese, 1892) [Hermaea]


  • Ercolania trinchesii Pruvot-Fol, 1951
  • Hermaea carminis Fez, 1962
  • Hermaea cremoniana Trinchese, 1892 (original)

The specimens can reach a size of 10 mm in length. The coloration is very peculiar and distinctive from other saccglossans. The head, the rhinophores, the back and sides of the animal and the upper third of the cerata are dark purple, almost black, while the head veil, the foot, the basal third of the cerata and a band on each side of the body are yellow gold. The body is very slim, the head has a rounded fold or cephalic veil. The rhinophores are auriculate and slightly wider at the base, there is a grayish-white longitudinal band on the outside of the rhinophores that continues behind their base, forming a “V” feature near the eyes. The cerata are fairly numerous and evenly cover the back of the animal, showing no clear sign of grouping. Their size increases from the ones located in the sides to the ones located dorsally. The shape of the cerata is elongated, with an enlarged mittle part and a sharpened tip. The cardiac region is in the dorsal half, at the height of the first cerata, and right before it there is the anal papilla, colored deep purple but with a white top. The foot is narrow, the anterior part somewhat broadened and the tail is short and narrow.

This species usually lives in shallow waters between different photophilic algae as Halimeda tuna, several Rhodophycean and Phaeophycean algae and also in Posidonia oceanica meadows . In Japan this species have been found to eat the thalli of the chlorophycean algae Derbesia but with European specimens nothing else is really known about their food, as nothing is known about where or how it gets the decorating pigment for the body. The spawn is an egg ribbon in the shape of a crescent or a nearly complete circle, with a diameter of 2 mm; eggs are small, of about 50-60 microns in diameter.


  • Placida. From Latin “placeō”, please, satisfy. Also means placid, gentle, quiet, still, calm, mild, peaceful.
  • Cremoniana. From Cremona, city located in the North of Italy, between Pavia and Parma, near Genoa.

This species was originally described from the coast of Naples but since then, it has been cited in the Mediterranean Sea (both in Eastern and Western coasts) and the near Eastern Atlantic (Canaries, Madeira and Azores), and also in the eastern Pacific (Japan, Guam, Marianas Islands, Australia and Indonesia). In the Iberian Peninsula it has been observed in most of its coastline, both Mediterranean and Atlantic and in the Balearic islands. In Catalonia it is easy to spot on seaweeds hanging from rocky walls in the Costa Brava.

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

References for the species: Placida cremoniana

    Portugal: García-Gómez et al. (1991). Andalucía (Atl.): Cervera (1988). Gibraltar: García-Gómez (1983), García-Gómez et al. (1989). Andalucía (Med.): Ballesteros et al. (1986), García Raso et al. (1992), Ocaña et al. (2000). Levante: Fez (1974, as Hermaea carmeni), Templado, Talavera and Murillo (1983), Marín and Ros (1987, 1988). Catalunya: Ballesteros (1980a, 1980b, 1985, citada como Hermaea). Baleares: Ballesteros, Álvarez and Mateo (1986). Canarias: Ortea et al. (1998, 2001), Moro et al. (2003), Wirtz and Debelius (2003). Azores: Fontes, Tempera and Wirtz (2001), Wirtz and Debelius (2003).

    Sources: Cervera et al., 2004, Ballesteros, 2007 & 2016, McDonald, 2006 and other sources.


    Western Mediterranean:
    Eastern Mediterranean:
    Atlantic Ocean:
This chart displays the observation probability for Placida cremoniana based on our own records.

More pictures


Further reading

Cite this article as:

Ballesteros, Manuel, Enric Madrenas, Miquel Pontes (2012-2018) "Placida cremoniana" in OPK-Opistobranquis, Published: 14/05/2012, Accessed: 23/01/2018 at (

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