Placida verticilata Ortea, 1982
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 verticilata Ortea, 1982
The specimens of this species tend to measure between 7 and 10 mm in length. The background body color is whitish but it is masked by the greatly developed diverticulae of the digestive gland, branching throughout the body (back, head, body sides, rhinophores, anal papilla, cerata and foot) and, being filled with chloroplasts, provide an olive green coloration to the entire animal. The rhinophores are thin and long and they are grooved along their front side. The eyes are inconspicuous and are located right behind the base of rhinophores. The anal papilla is tubular, long and narrow and is located ahead of the heart area, right below the first dorsal cerata. The digestive gland branches extraordinarily throughout the body sometimes not allowing to distinguish the main hepatic ducts. There are about 30-40 cerata on the back, they are elongated and fusiform and have a rounded tip; within each cerata there is a thick olive green hepatic duct that alternately grows rounded short ramifications of the same colour to one side and another. The foot is whitish and rounded ahead, where it forms two rounded lateral lobes.
Morphological note: P. verticilata is very similar to P. dendritica, there are distinguished by longer and simply grooved rhinophores -they are auriculate and rolled in P. dendritica– and the ramifications of the digestive gland within the cerata, in P. verticilata they are simple and convoluted, while in P. dendritica they are complexely branched.
This kind of sacoglossan lives, as the similar species P. dendritica on the thalli of the branched chlorophycean algae of the genus Codium, on which it feeds and with which it keeps a perfect color mimicry. As in other sacoglossans, it does not digest the ingested chloroplasts from the algae but they are accumulated instead in the complex ramifications of the digestive gland. These chloroplasts are kept functional for several weeks, and as they perform photosynthesis, they synthesize organic compounds, to the advantage of the sacoglossan. The spawn consists of a tightly wrapped flattened ribbon forming a flat spiral; Eggs are white and they are enclosed in nearly spherical egg capsules of about 140 microns in diameter (Ortea, 1981; Garcia-Gomez, 1987).
- Placida. From Latin “placeō”, please, satisfy. Also means placid, gentle, quiet, still, calm, mild, peaceful.
- Verticilata. From Latin “verticillus”, meaning “with whorls.” Because of the whorled layout of the digestive branches in the cerata. In biology a whorl is a set of three or more leaves, branches or other organs sprouting from a base at the same level.
This is a species that has been cited so far in the coasts of the English Channel (Muller, 2004), the Canary Islands, Azores, Madeira (Borges et al. 2010), the Iberian Peninsula and the Caribbean (Costa Rica, Cuba; Miloslavich et al, 2010). In the Iberian Peninsula (Cervera et al. 2004) it has been reported on the Cantabrian coast, in Portugal, Strait of Gibraltar and the Andalusian Mediterranean. In Catalonia it has been recently observed in different parts of the Costa Brava (Medes Islands, Cala Aiguafreda, Tossa de Mar). Possibly its range is wider, as it has been probably misidentified with Placida dendritica due to the similarity of their morphology, color and substrate.
| : OBIS|
: GROC 2010-2011
: Enric Madrenas
: João Pedro Silva
: Bernard Picton
| : OPK|
: Manuel Ballesteros.
: M@re Nostrum
: Altres fonts
: Marine Regions
References for the species: Placida verticilata
- Cantabria: Ortea (1977a,c, as Hermaea viridis).
Portugal: Calado et al. (2003).
Gibraltar: García-Gómez (1987), Sánchez-Moyano et al. (2000).
Andalucía (Med.): Sánchez Tocino, Ocaña and García (2000a).
Levante: Marín and Ros (1988).
Canarias: Ortea (1981), Ortea et al. (1998, 2001), Moro et al. (2003).
Madeira: Malaquias (unpubl. data).
Azores: Ávila (2000), Malaquias (2001).
Sources: Cervera et al., 2004, Ballesteros, 2007 & 2016, McDonald, 2006 and other sources.
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