Cuthonellidae (Miller, 1971)

Broms, Fredrik, 2024, Diversity of nudibranchs in shallow water habitats in the region of Tromsø, northern Norway, Fauna norvegica 43, pp. 84-109 : 100

Family Cuthonellidae (Miller, 1971)

Cuthonella concinna (Alder and Hancock, 1843) Figure 5D

Material examined: One specimen, UTE, 03 November 2021, 10 mm, FB, NUIT-1011 ( Figure 5D ) ; Three specimens, UTE, 17 November 2021, 11, 10, 8 mm, FB, NTNU-VM-84576/NUIT-1020, NTNU-VM-84566/NUIT-1021, NTNU-VM-84577/NUIT-1022 ; One specimen, ESU, 05 May 2022, 11 mm, FB, NTNU-VM-85698/ NUIT-1163 ; One specimen, RAK, 29 May 2022, 24 mm, FB, NTNU- VM-85701/NUIT-1169 .

Localities: ESU, RAK, SGU, UTE

Distribution and remarks: Cuthonella concinna was previously reported only from southern Norway ( Evertsen & Bakken 2005). Recent observations indicate also a more northerly distribution ( Lundin et al. 2020; Artskart 2024). C. concinna has also been reported from northern Russia ( Martynov et al. 2006) and larvae have been detected in the meroplankton in the Barents Sea ( Descôteaux et al. 2021). These findings agree well with the results from this study where C. concinna was found to be a common species in the Tromsø region. Most animals were found in close proximation to the hydroid Dynamena pumila Linnaeus, 1758 in the Ascophyllum nodosum belt. Animals were recorded all year round. Spawning occurred from May – July and juvenile animals appeared in October – November. Animals were often found emerged above water during low tide, also in winter when they could be found totally surrounded by ice crystals. The present records are the first records from the Tromsø region.

Figures

Figure 5. A. Coryphella verrucosa, verrucosa form, NTNU-VM-85676/NUIT-1261, B. Carronella sp., NTNU VM-84466/NUIT-1121, C. Edmundsella pedata, NUIT-1035, D. Cuthonella concinna, NUIT-1011, E. Cuthona nana, NTNU VM-85646/NUIT-1242, F. Amphorina andra, yellow form, NTNU-VM-85702/NUIT-1236, G. Amphorina andra, white form, NTNU-VM-84468/NUIT-1032, H. Amphorina andra, white-orange form, NTNU- VM-84496/NUIT-1006-1, I. Amphorina pallida, strongly pigmented form, photo record, 12 December 2020, J. Amphorina pallida, pale form, photo record, 01 February 2022, K. Eubranchus exiguus, NUIT-1334, L. Eubranchus rupium, photo record, 17 August 2021. Scale bar: 10 mm. All photos: Fredrik Broms.