Elysia margaritae

Elysia margaritae De Fez, 1962

Elysia margaritae Fez, 1962 @ Salento, Italy by Fabio Vitale

Taxonomic Note: This is a rare sacoglossan species whose taxonomic identity has been questioned due to the lack of confirmed observations since its original description. However, the type locality of Elysia margaritae (Port of Valencia, eastern coast of Spain) has undergone heavy anthropogenic impacts since De Fez (1962) found three large specimens of this species. The three specimens of E. margaritae reported by Martín-Hervás et al. (2024) were collected in Lecce, southeastern Italy, and matched the original description by De Fez (1962), but with slight differences in radular morphology: De Fez identified radular teeth with a smooth lower cutting edge in the dissected specimen, whereas Martín-Hervás et al. (2024) used scanning electron microscopy (SEM) and noted fine, small denticles along the edge, which likely went unnoticed in the original observations using a binocular magnifying glass. The newly collected specimens were sequenced and clustered phylogenetically with another GenBank specimen previously identified as Elysia translucens (voucher #845), collected from Banyuls-sur-Mer, France (Christa et al., 2014). These recent molecular and morphological analyses confirm the separation of E. margaritae from Elysia gordanae by a 14.2% divergence in the COI gene (Martín-Hervás et al., 2024), despite its previous synonymization by Ortea et al. (1997; 2017). Key distinguishing features of E. margaritae include smooth parapodial edges, a bright green body with small light-blue spots, and differences in radular morphology.

Description
Body relatively long and wide, tapering slightly towards the posterior end, with a maximum recorded length of 15 mm (Martín-Hervás et al., 2024) and 40 mm (De Fez, 1962). Its coloration is greenish, with small light-blue spots irregularly distributed on the inner and outer sides of the parapodia and on the head. Some scattered white dots may also be present on the head and the sides of the parapodia. The parapodia are large, extending to the posterior end of the body and displaying undulating edges. The rhinophores are relatively long, rolled, and truncated at the tip, sharing the body’s uniform green coloration. The eyes are small and located behind the rhinophores. Dorsal renopericardial prominence rounded with two ‘vessels’ radiating from each side, branching irregularly on the inner face of each parapodium. The foot sole is slightly narrower than the body, lighter in coloration than the dorsum, and tapers to a rounded posterior end.

Biology
Elysia margaritae inhabits infralittoral zones at depths of up to 15 meters. It has been recorded from various coastal locations in Italy and France, though it remains an extremely rare species. As a sacoglossan, E. margaritae is presumed to engage in kleptoplasty, feeding on specific algal species and retaining functional chloroplasts within its body for photosynthesis. However, its exact dietary preferences have yet to be documented. Little is known about its reproductive biology. Like other Elysia species, it is hermaphroditic, engaging in reciprocal copulation and laying egg masses on algal substrates.

Similar Species

• Elysia gordanae. This species has conspicuous white pustules on the parapodial edges and sides, which are absent in E. margaritae, whose parapodial edges are smooth. Adult E. gordanae typically measure less than 10 mm, whereas E. margaritae has reached a maximum recorded size of 40 mm, although recently discovered specimens in Italy measured 15 mm. The general body coloration of E. gordanae is translucent green with superficial iridescent red, white, and blue specks, sometimes giving it an orange appearance. In contrast, E. margaritae presents a bright green base color with small light-blue spots irregularly arranged on the outer side of the parapodia.

Etymology

• Elysia. It is a girl’s name of Latin origin, derived from the word Elysium, which in mythology is the home of the blessed, known as the “Elysian fields”. The name Elysia also means “God’s oath” in Hebrew. Frieder Sauer comments that Elysia means heavenly.
• Margaritae. In honor of Margarita Ibáñez, who obtained many specimens for the author’s collection (De Fez, 1962).

Distribution
Elysia margaritae is known only from the Mediterranean Sea, with confirmed records from Valencia, Spain (De Fez, 1962; type locality), Banyuls-sur-Mer, France (Christa et al., 2014, as Elysia translucens), and multiple sites along the western and eastern coasts of Puglia, Italy (Furfaro et al., 2020; Martín-Hervás et al., 2024). The other Atlantic and Mediterranean records correspond to other species, due to the incorrect synonymization by Ortea et al. (1997, 2017) with Elysia gordanae.  

More pictures

Bibliography

1246567 Elysia margaritae 1 eunomia-revista-en-cultura-de-la-legalidad 50 creator asc 1 46319 https://opistobranquis.info/wp-content/plugins/zotpress/
Bibliography based on the works by Steve Long, 2006. Bibliography of Opisthobranchia 1554-2000 and Gary McDonald, 2009. Bibliographia Nudibranchia, with later updates from other resources.

Further reading

• Biodiversity Heritage Library
• Flickr pictures
• NCBI GenBank
• OBIS - Search by Taxon
• Salento Sommerso
• World Register of Marine Species

Cite this article as: