Polycera norvegica ( Sørensen, Rauch, Pola & Malaquias, 2020 )

Broms, Fredrik, 2024, Diversity of nudibranchs in shallow water habitats in the region of Tromsø, northern Norway, Fauna norvegica 43, pp. 84-109 : 92-93

publication ID	https://doi.org/10.5324/fn.v43i0.5840
persistent identifier	https://treatment.plazi.org/id/03D0903A-C535-B813-EC28-1E1908C2F9CA
treatment provided by	Felipe
scientific name	Polycera norvegica ( Sørensen, Rauch, Pola & Malaquias, 2020 )
status

Treatment

Polycera norvegica ( Sørensen, Rauch, Pola & Malaquias, 2020) View in CoL

Figure 2K View Figure 2

Material examined: One specimen, HIL, 27 November 2021, FB, NUIT-1071 ; Four specimens, HIL, 04 September 2022, 22, 27, 25, 22 mm, FB, NTNU-VM-85678/NUIT-1213, NTNU-VM-85659/NUIT-1216, NTNU-VM-85663/NUIT-1217, NTNU-VM-85641/NUIT-1218 ( Figure 2K View Figure 2 ) ; One specimen, HIL, 15 October 2022, 20 mm, FB, NTNU-VM-85673/NUIT-1234 ; Two specimens, EKJ, 21 September 2023, 24, 23 mm, FB, NUIT-1323, NUIT-1324 ; One specimen, HIL, 14 November 2023, 16 mm, FB, NUIT-1339 .

Localities: EKJ, HIL, TVK

Distribution and remarks: Polycera norvegica is a newly described species which was recently separated from Polycera quadrilineata ( Sørensen et al. 2020) . Earlier records of the species are, therefore, naturally sparse. The present study found P. norvegica to be a commonly occurring nudibranch in the Tromsø region during autumn and winter. Animals were typically found associated with the bryozoans Electra pilosa and Membranipora membranacea growing on Desmarestia aculeata and Saccharina latissima respectively. Specimens belonging to chromatic variants II, III, and IV ( Korshunova et al. 2021) were observed. In addition, several very dark specimens, presumably belonging to a previously unknown chromatic variant, were recorded (e.g. NTNU-VM-85659/NUIT-1216, NUIT-1323, NUIT-1324). The current observations are the first published records of Polycera norvegica from the Tromsø region.

Polycera quadrilineata (Müller, 1776) Figure 2L View Figure 2

Material examined: One specimen, TVK, 09 October 2020, FB, photographic record ( Figure 2L View Figure 2 ) ; One specimen, KVA, 14 November 2021, 20 mm, FB, NUIT-1023 ; One specimen, SKI, 06 August 2022, 23 mm, FB, NTNU-VM-85700/NUIT-1201 ; One specimen, EKJ, 05 October 2022, 14 mm, FB, NTNU-VM-85667/NUIT-1223 .

Localities: EKJ, HIH, HIL, KFS, KVA, SKI, THA, TPO, TPR, TTE, TVK, UTE

Distribution and remarks: Considered a southernly species ( Evertsen & Bakken 2005), Polycera quadrilineata has recently been recorded north to Lofoten ( Artsdatabanken 2021) and southern Troms ( Moen & Svensen 2020; Sørensen et al. 2020; Lundin & Malmberg 2021). In Russian waters the species was observed for the first time in 2005 ( Martynov et al. 2006). Previous records of Polycera quadrilineata are, however, in need re-examination as recent taxonomic revision has recently separated a morphologically similar species Polycera norvegica (see this species) from P. quadrilineata ( Sørensen et al. 2020; Korshunova et al. 2021; Malaquias et al. 2021). The present study found both “true” P. quadrilineata and P. norvegica sympatrically in the same habitat. Whereas both species were found mainly on Saccharina latissima encrusted with Membranipora membranacea , P. quadrilineata seemed to prefer M. membranacea while P. norvegica was more often observed associated with Electra pilosa . Specimens of P. quadrilineata observed during this study belonged mainly to chromatic variants II and IV as described by Korshunova et al. (2021). A few individuals of variants V and VI as well as one specimen of variant VII were also observed. The present records are the first records of P. quadrilineata from the Tromsø region.