Polyceridae (Alder & Hancock, 1845)

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

publication ID	https://doi.org/10.5324/fn.v43i0.5840
persistent identifier	https://treatment.plazi.org/id/03D0903A-C535-B812-EFCC-1D1A0BA1F98A
treatment provided by	Felipe
scientific name	Polyceridae (Alder & Hancock, 1845)
status

Treatment

Family Polyceridae (Alder & Hancock, 1845) View in CoL

Limacia clavigera (O. F. Müller, 1776) Figure 2H View Figure 2

Material examined: One specimen, HIS, 31 July 2023, 9 mm, FB, NUIT-1308 ( Figure 2H View Figure 2 ) .

Localities: HIS

Distribution and remarks: Limacia clavigera is a commonly occurring species along most of the Norwegian coast north to southern Troms. Further north, only a single unverified record from Finnmark has been reported ( Artskart 2024) and the study region seem to constitute the current northern limit in the species distribution. The specimen was found on Saccharina latissima with encrusting bryozoans. The present finding is the first documented record from the Tromsø region and the northernmost published record of the species.

Palio dubia (M. Sars, 1829) Figure 2I View Figure 2

Material examined: One specimen, ESU, 26 August 2020, FB, photographic record ( Figure 2I View Figure 2 ) ; One specimen, HIL, 08 April 2022, 16 mm, FB, NTNU-VM-85686/NUIT-1159 ; One specimen, 28 October 2022, 24 mm, FB, NUIT-1238.

Localities: EKJ, ESU, HIL, KVA, THA, TPR, UTE

Distribution and remarks: Palio dubia has previously been found along the entire Norwegian coast ( Evertsen & Bakken 2005) including one online record from Tromsø ( Artskart 2024). P. dubia has been reported to occur on hard-bottom at 10 – 100 m depth ( Moen & Svensen 2020; Lundin & Malmberg 2021) with most observations deeper than 20 m ( Evertsen & Bakken 2005). By contrast, this study found most specimens in the Ascophyllum nodosum belt where they were often found emersed above water between tides. Animals were observed at all months of the year except during summer. This study verifies the species presence in the region.

Palio nothus (Johnston, 1838) Figure 2J View Figure 2

Material examined: One specimen, KVA, 23 October 2021, 8 mm, FB, NUIT-1040 ; One specimen, UTE, 17 November 2021, 7 mm, FB, NUIT-1018 ; One specimen, HIL, 15 October 2022, 9 mm, FB, NUIT-1227 ; One specimen, HIL, 24 September 2023, 7 mm, FB, NUIT-1326 ( Figure 2J View Figure 2 ) .

Localities: HIL, KVA, UTE

Distribution and remarks: Palio nothus has sometimes been confused with the more common and widespread Palio dubia in the literature. Consequently, when historical records of P. nothus from Norway were reviewed only two records of P. nothus were found from Norwegian waters ( Evertsen & Bakken 2005). In addition, a third, more recent, observation from Vestland County was reported in 2013 ( Evertsen & Bakken 2013) suggesting that the species is very rare in Norway. A few unpublished online records from southern Norway also exist ( Artskart 2024). All four specimens recorded by the present study were found during autumn (September – November.) One specimen was found in the Ascophyllum nodosum belt in the intertidal. The other three were found at fouling community localities on bare surfaces or on Desmarestia aculeata encrusted with Electra pilosa . The present records are the first records from the Tromsø region and significantly extends the known range of distribution of the species to 69 degrees N.