Polycera norvegica

Polycera norvegica Sørensen, Rauch, Pola & Malaquias, 2020

Polycera norvegica @ Ouessant, France (CC BY) iNaturalist by François Roche

Taxonomy

	Superdomain	Biota
	Kingdom	Animalia
	Phylum	Mollusca
	Class	Gastropoda
	Subclass	Heterobranchia
	Infraclass	Euthyneura
	Subterclass	Ringipleura
	Superorder	Nudipleura
	Order	Nudibranchia
	Suborder	Doridina
	Infraorder	Doridoidei
	Superfamily	Polyceroidea
	Family	Polyceridae
	Subfamily	Polycerinae
	Genus	Polycera
	Species	Polycera norvegica Sørensen, Rauch, Pola & Malaquias, 2020

	Classification according to Bouchet et al. (2017) Taxonomic source: World Register of Marine Species (AphiaID: 1451585).

Taxonomical note: Until 2020, morphotype of Polycera norvegica Sørensen, Rauch, Pola & Malaquias, 2020 was included within most published descriptions of P. quadrilineata. Korshunova et al (2021) published their work on Polycera quadrilineata complex, where four species from the European Atlantic shores were recognized, including a new species for science, Polycera kernowensis, based on a multidisciplinary (molecular, morphological, phylogenetic, phylogeographical and ecological) approach to species determination. In this work, the authors have treated the nudibranch species Polycera norvegica as a junior synonym of Polycera capitata (original designation: Thecacera capitata), but Malaquias et al. (2022) show that, in accordance with the ICZN, Thecacera capitata (and in consequence also Polycera capitata) should be considered a nomen dubium, so they reinstate Polycera norvegica as the valid name for that species, as per Sørensen et al. (2020).

Synonyms

Polycera capitata (Alder & Hancock, 1854) > nomen dubium
Thecacera capitata Alder & Hancock, 1854

Description
Body elongated, up to 14 mm long, limaciform, with a distinct marginal ridge. Body is highest and widest in the middle part, close to anus, gills and papillae, and ends in tappered tail. Body surface smooth, covered with scattered flattened tubercles, which are variable in number and size. In specimens with dotted morphotype these tubercles tend to be colored in light yellow. There is an frontal veil on the anterior part of the body, with 4-7 digitiform, yellow or orange coloured processes with whitish tips that point forward. Specimens with dotted morphotype often with only yellow spots scattered on a whitish translucent body background. Rhinophores are not retractile and have 6-10 lamellae, with stems slightly leaning forward and a cylindrical mucron in the distal end. Eyespots are on the notum, right behind the rhinophores, almost indistinguishable in some specimens. Gill is formed by 7–11 pinnate leaves that could be of different sizes. They are partially retractile into a pocket in the notum. There is an elongate and narrow papillae on each side of the gills, pointing backwards or laterally, that are shorter and stubby with rounded apical tip on individuals with dotted morphotype, and slender with sharper apical tips on individuals with yellow / orange morphotype.

There are two main colour morphs present:

Dotted colour morph (Figure A) – base colour translucent white with black, dark brownish or grey dots scattered over entire surface. Brown/orange patches present on head region or sometimes randomly along body surface. Rhinophores translucent white; lamellae sometimes with a weak hint of light yellow pigmentation; stem sometimes dark brown or grey (Figure B). Frontal veil processes translucent white, with few scattered yellow patches randomly distributed. Posterior papillae white with yellow tips; sometimes white basal part dotted with yellow or black patches. Gills whitish with yellow, orange, or black spots along rachis and tips.
Colour forms of Polycera norvegica by C.G.Sørensen
Yellow/orange colour morph (C), but in the studied specimens the rhinophore stems were always whitish lacking black pigmentation. Faint greyish tiny spots may be present on head region and gills.

Biology
Sublittoral species occurring between 2–15m depth, often on kelp (Laminaria spp.).

Etymology

Polycera. From Greek “polys”, many + “keras”, horns.
Norvegica. From Latin “norvegicus”, of or pertaining to Norway.

Distribution
European Atlantic shores from Norway to Spain and Portugal, common around the British Isles and Ireland.

Known georeferenced records of the species: Polycera norvegica
Sources:
: OBIS : GROC 2010-2011 : Enric Madrenas : João Pedro Silva : Bernard Picton : GBIF.ORG	: OPK : VIMAR : Manuel Ballesteros. : M@re Nostrum : Altres fonts : Marine Regions

Abundance

Western Mediterranean:	☆☆☆☆☆
Eastern Mediterranean:	☆☆☆☆☆
Atlantic Ocean:	★☆☆☆☆

Month

This chart displays the monthly observation probability for Polycera norvegica based on our own records.

More pictures

Polycera norvegica @ Baleal, Portugal by Joao Pedro Silva (CC BY) iNaturalist

Polycera norvegica @ Norway by Heine Jensen (CC BY) iNaturalist

Polycera norvegica @ Ouessant, France by Pierre Corbrion (CC BY) iNaturalist

Polycera norvegica @ Ouessant, France by Sylvain Le Bris (CC BY) iNaturalist

Polycera norvegica @ Ribeira, A Coruña by Mergullo (CC BY) iNaturalist

Polycera norvegica @ St. Abbs, Scotland by Jim Greenfield (CC BY) iNaturalist

Polycera norvegica @ UK by Becky Hitchin (CC BY) iNaturalist

Colour forms of Polycera norvegica by C.G.Sørensen

Bibliography

Steve Long, 2006

Bibliography of Opisthobranchia 1554-2000

Gary McDonald, 2009

Bibliographia Nudibranchia

Further reading

Cite this article as:

Pontes, Miquel (2023) "Polycera norvegica" in OPK-Opistobranquis. Published: 09/02/2023. Accessed: 30/09/2023. Available at (https://opistobranquis.info/en/?p=37639)

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Polycera norvegica