Polycera faeroensis

Polycera faeroensis  Lemche, 1929

Polycera faeroensis @ Granada by Luis Sánchez-Tocino

Taxonomical note: Korshunova et al (2021) published their work on Polycera quadrilineata complex, where four species from the European Atlantic shores were recognized, based on a multidisciplinary (molecular, morphological, phylogenetic, phylogeographical and ecological) approach to species determination. In this work, the authors determined that Polycera faeroensis reports included another cryptic species (new to science) that they have named Polycera kernowensis, that can be easily determined by the shape of the structure protecting the gills, one pair of single lateral processes in P. kernowensis, and one pair  of wing-like lateral lobes with multiple small tubercles or projections in P. faeroensis, among other anatomical differences.

Description
Body up to 45 mm long, smooth, semitransparent white with yellow / orange tipped appendages and yellow edge to the tail and foot. It generally lacks yellow spots on the dorsum and body sides, but there could be some. Frontal veil with 6-8 yellow oral tentacles, maximum 14. Ventrally, the head extends into broad oral flaps with some small irregular yellow marks. Rhinophores could be brownish and the distal part has between 18-19 lamellae, maximum 25. Gills are located behind the pericardium and composed of 6-7 branchial leaves, maximum 11. Protecting the gills there are a pair of characteristic wing-like lateral lobes with multiple small, yellow tubercles, more or less evident.

Biology
It lives in rocky bottoms down to 35m, despite in the Faroes it was reported at 120m of depth. It preys on bryozoans Membranipora membranacea, Crisia denticulata, other species of Crisia and the hydroid Hydrallmania falcata (Thompson & Brown, 1976). This species spawns in July in the Atlantic. The egg-string is a ribbon forming a simple coil attached to the substrate by one side, that is slightly widened.

Etymology

• Polycera. From Greek “polys”, many + “keras”, horns.
• Faeroensis. From the Faroe Islands (Denmark).

Distribution
Type specimen collected at the Faroe Islands in 1899, it has also been found in the coast of Sweden and the British Isles. Probably it can also be found in the coasts of Denmark and Netherlands. Also present in the Atlantic shores of Spain and Portugal, in the Northern shores of the Alboran Sea, and two records from Mallorca and Cadaqués (Spain).

More pictures

Bibliography

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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

• AsturNatura
• Biodiversity Heritage Library
• DORIS
• El Litoral de Granada
• Encyclopedia of Marine Life of Britain and Ireland
• Flickr pictures
• GROC
• Interim Register of Marine and Nonmarine Genera
• NCBI GenBank
• OBIS - Search by Taxon
• Scottish Nudibranchs
• Sea Slug Forum
• World Register of Marine Species

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