Petalifera petalifera
(Rang, 1828)

Order: ANASPIDEA
Superfamily: APLYSIOIDEA
Family: Aplysiidae

DISTRIBUTION

Mediterranean and eastern Atlantic. Possibly more widely spread but a better understanding of the genus worldwide is required before we can determine whether this species has a wider distribution.

PHOTO

Locality: middle Adriatic, Croatia. Depth: unrecorded. Length: approx. 20 mm. Caulerpa taxifolia settlement. Photographer: A. Zuljevic

A very flattened Sea Hare, in which the parapodia are reduced and fused, except for a small postero-dorsal opening into the mantle cavity, which is covered by a pair of small rounded flaps. The body is translucent with a close scattering of green to brown specks, which appear to be embedded in the skin. The translucent body enables this species to be well-camouflaged on the sea grass leaves and algae on which it lives, the colour of the plant showing through the body of the slug. It grows to about 40mm in length.

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) and its anatomy and nomenclatural history redescribed by Martinez (1996).Petalifera petalifera has been confused in the literature with Phyllaplysia lafonti [see message #13719]. Terreni (1997) compares and illustrates both species from the Mediterranean. A photo (Ocana, 2000) identified as P. petalifera, from the Straits of Gibraltar, is P. lafonti. I have also moved the following messages, previously identified as P. petalifera, to P. lafonti [#9017, #5433].

• Fasulo, G., Izzillo, F., Russo, G. F., Toscano, F., and Villani, G. (1984) Nota su Petalifera petalifera (Rang, 1828) (Gastropoda, Opisthobranchia, Aplysiomorpha), specie Mediterranea poco conosciuta. Considerazioni sistematiche, ecologiche e biogeografiche. Bollettino Malacologico, 20: 263-272.
• Fischer, P (1870) Observations sur les Aplysies. Ann. de Sci. Nat (5). Zool & Pal, 13: 3
• Fischer, P (1872) Description d'une espece nouvelle du genre Phyllaplysia. Journal de Conchyliologie, 20: 295-301.
• Martinez, E. (1996) On Petalifera petalifera (Rang, 1928) (Gastropoda: Opisthobranchia): new anatomical and geographical data. Journal of Molluscan Studies, 62: 243-250.
• Ortea, J.A. & Martínez, E. (1991) El Orden Anaspidea (Mollusca: Opisthobranchia) en las Islas Canarias. Rev. Acad. Canar. Cienc., 3(4): 87-107.
• Rang, S. (1828) Histoire naturelle des Aplysiens, premiere famille de l'ordre des Tectibranches. In: Histoire naturelle Generale et particuliere des Mollusques. Firmin Didot, Paris, 84pp. Pls. 1-24.
• Terreni, G. (1997) Rinvenimento di un esemplare di Phyllaplysia lafonti (P. Fischer, 1870) nelle acque litorali di Livorno (Gastropoda, Opisthobranchia, Aplysiomorpha). La Conchiglia, Roma, 29 (282): 45-47.

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