Dendronotus dalli Bergh, 1879

Ekimova, Irina A., Grishina, Darya Yu. & Nikitenko, Ekaterina D., 2024, Nudibranch molluscs of Sakhalin Island, Northwestern Pacific: new records and descriptions of two new species, Ruthenica, Russian Malacological Journal 34 (2), pp. 69-91 : 80-81

Dendronotus dalli Bergh, 1879

( Fig. 7B, F, G)

Material studied: MIMB42234 , 8 specimens, Sea of Okhotsk, NE Sakhalin Is. , 52°12′4″N, 144°26′8″E, depth 218– 192 m, 30 July 2019, coll. A. Mayorova. MIMB48049 , 1 specimen, Sea of Okhotsk, NE Sakhalin Is. , 52°12’4”N, 144°26’48.0”E, depth 165-168 m, 30 July 2019, coll. A. Mayorova. MIMB48050 – MIMB48053 , 4 specimens, Sea of Okhotsk, Sakhalin Is., Severny Bay , 54°27’9”N, 142°14’18.0”E, 38 m depth, 31 July 2019, coll. A. Mayorova. MIMB48054 , 1 specimen, Sea of Okhotsk, Sakhalin Is., Severny Bay , 54°29’8”N, 141°16’54.0”E, 58–59 m depth, 31 July 2019, coll. A. Mayorova. MIMB48055 , 1 specimen, Sea of Okhotsk, Sakhalin Is., Aniva Bay , Moguchi River , Hirano ridge, 46°04.978’N, 142°13.021’E, 15–18 m depth, 19 August 2023, coll. A. Plaksin, A. Semenov. MIMB48056 – MIMB48060 , 5 specimens, Sea of Okhotsk, Sakhalin Is., Aniva Bay , Moguchi River , Hirano ridge, 46°05.372’N, 142°13.612’E, 20 m depth, 20 August 2023, coll. A. Plaksin, A. Semenov. MIMB48061 – MIMB48066 , 6 specimens, Sea of Okhotsk, Sakhalin Is., Aniva Bay , Moguchi River , Hirano ridge, 46°04.826’N, 142°12.985’E, 13 m depth, 23 August 2023, coll. A. Plaksin, A. Semenov.

Diagnosis: Body elongated, up to 80 mm in length, uniform milky-white to pink and salmon. Large oral veil with up to 10 branched oral appendages, rhinophoral sheath with up to five branched appendages, lateral papilla present, up to six pairs of dorsolateral appendages with extensive secondary and tertiary branching, terminal branches with opaque white pigmentation. Jaws elongate with slightly curved masticatory border bearing single row of blunt denticles. Radular formula 36 × 11–12.1.11–12. Triangular smooth rachidian tooth. Lateral teeth elongated, narrow, with large cusp and 3–4 small denticles. Ampulla large, folded. Prostate with few alveolar glands. Penis slightly curved.

Molecular data: The intraspecific p- distance in COI marker was 1,7%. A BLAST-n search of COI sequences resulted in up to 99% identity to sequences of D. dalli from GenBank thus confirming distinctness of studied specimens.

Distribution: This species is widely distributed in the North-West Pacific, including Kamchatka [Ekimova et al., 2015], the Kurile Islands [ Ekimova et al., 2021a], the Commander Islands [ Martynov, 2006], Sakhalin Is. [ Chichvarkhin, 2016, this study], the Sea of Japan [ Korshunova et al., 2020c]. It was also found in the Chuckchi Sea [ Ekimova et al., 2019]. In the North-East Pacific this species is known from Alaska to Washington [ Robilliard, 1970]. This species has a wide bathymetric range, being found from 5 to 227 m in depth [ Ekimova et al., 2021a; this study].