ERMS note details

The identity of the small sea hares of the genera Phyllaplysia and Petalifera is very confused. The situation is also confused by many authors considering that species of Phyllaplysia lacked a shell while those of Petalifera possessed one. The original description of Petalifera petalifera is not easy to interpret, but most authors have accepted it to apply to a reasonably common, small translucent sea hare covered in an irregular pattern of brown to green patches and diffuse spots. It has been reviewed and illustrated by Fasulo et al. (1984) and Terreni (1997). Phyllaplysia lafonti was originally described from Baie d'Arcachon on the Atlantic coast of France. Like all species of Phyllaplysia and Petalifera it is described as small, flattened, and with very reduced parapodia. The colour is described as very variable, but one distinctive feature of the written desription and the accompanying drawing are the way the body consists of concentric bands ['zones concentriques'] of lighter and darker pigmentation. Also described are whitish spots ringed with purple. Fischer was unable to determine whether there was a shell but Terreni (1997) illustrates a relatively large fragile internal shell. It is hard to be sure which of the earlier references to this species in the Mediterranean are actually correct, but there are some good colour photos of correctly identified Phyllaplysia lafonti in an article by Terreni (1997) in La Conchiglia. In this article he compares it with Petalifera petalifera.
Cervera J.L., Calado G., Gavaia C., Malaquias M.A.E., Templado J., Ballesteros M., García-Gómez J.C. & Megina C. (2004). An annotated and updated checklist of the opisthobranchs (Mollusca: Gastropoda) from Spain and Portugal (including islands and archipelagos). <i>Boletín. Instituto Español de Oceanografía </i>: 20(1-4): 122 pp. available online at Available for editors  PDF available
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