Elysia Risso, 1818

Wägele, Heike, Stemmer, Kristina, Burghardt, Ingo & Händeler, Katharina, 2010, Two new sacoglossan sea slug species (Opisthobranchia, Gastropoda): Ercolania annelyleorum sp. nov. (Limapontioidea) and Elysia asbecki sp. nov. (Plakobranchoidea), with notes on anatomy, histology and biology, Zootaxa 2676, pp. 1-28 : 16

Elysia Risso, 1818

Type species: Notarchus timidus Risso, 1818 , by monotypy.

Comments and diagnosis. In spite of several older diagnoses of the genus, Jensen (1996) could not identify any apomorphic characters which are shared by all species referred to the genus Elysia , and this is still valid. Nevertheless, recent phylogenetic analyses based on several molecular markers ( Händeler et al. 2009) indicate the monophyly of the genus Elysia . We refer here to one of the most recent descriptions ( Jensen 1993) indicating the most prominent character for Elysia : pharynx without pharyngeal pouches (although this is shared by many sacoglossan genera, except within the Plakobranchoidea). Furthermore Elysia species are described with long blade-shaped radular teeth with a median denticulate cutting edge ( Bouchet 1984; Thompson & Jaklin, 1988; Gosliner 1995) and broad parapodia ( Thompson 1973).