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:

  1. 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

    Colour forms of Polycera norvegica by C.G.Sørensen

  2. 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

Bibliography

    Alder J, Hancock A. 1854. Notice of some new species of British Nudibranchiata. Annals and Magazine of Natural History. 14(79):102–105. Available from www.biodiversitylibrary.org/page/2283472.
    Alder J, Hancock A. 1854. A monograph of the British nudibranchiate Mollusca: with figures of all the species. Ray Society, London. Available from www.biodiversitylibrary.org/item/131598#page/200/mode/1up.
    Korshunova TA, Driessen FMF, Picton BE, et al. 2021. The multilevel organismal diversity approach deciphers difficult to distinguish nudibranch species complex. Scientific Reports. 11(1):18323. https://doi.org/10.1038/s41598-021-94863-5.
    Malaquias MAE, Sørensen C, Rauch C, et al. 2022. Polycera norvegica is a valid species, and a plea for good taxonomic practices – a reply to Korshunova et al., 2021. Journal of the Marine Biological Association of the United Kingdom. 101(8):1203–1205. https://doi.org/10.1017/S0025315422000108.
    Smith I. 2022. Polycera quadrilineata (O. F. Müller, 1776) Identification and Biology. ResearchGate. https://doi.org/10.13140/RG.2.2.29936.94725.
    Sørensen CG, Rauch C, Pola M, et al. 2020. Integrative taxonomy reveals a cryptic species of the nudibranch genus Polycera (Polyceridae) in European waters. Journal of the Marine Biological Association of the United Kingdom. 100(5):733–752. https://doi.org/10.1017/S0025315420000612.
    Thompson TE, Brown GH. 1984. Biology of Opisthobranch Molluscs. Vol. 2. Ray Society, London 156, pp. 229:
    WoRMS Editorial Board. 2023. World Register of Marine Species. WoRMS. Available from http://www.marinespecies.org.

    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

Cite this article as:

Pontes, Miquel (2023) "Polycera norvegica" in OPK-Opistobranquis. Published: 09/02/2023. Accessed: 25/05/2024. Available at (https://opistobranquis.info/en/?p=37639)

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