Aeolidia papillosa (Linnaeus, 1761)

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 : 86-87

Aeolidia papillosa (Linnaeus, 1761)

( Fig. 7H)

Material studied: MIMB48078 , 1 specimen, dissected, the Sea of Okhotsk , Aniva Bay , Moguchi River, Hirano ridge, 46°05.372’N, 142°13.612’E, 20 m in depth, 20.08.2013, coll. A. Plaksin, A. Semenov.

Diagnosis: Body large, wide, 30 mm in length, yellowish to brown with intensive dark brown to black pigmentation on dorsal side of anterior body parts and head. Body, rhinophores and tips of cerata intensively covered by opaque yellow and black speckles. Rhinophores conical, smooth. Cerata cylindrical, slightly flattened near base, arranged in continuous, densely packed rows. Jaws oval plates with smooth masticatory border. Radular formula 19 × 0.1.0. Wide rachidian tooth pectinate with 28–35 sharply pointed denticles. No central cusp visible. Ampulla narrow, convoluted. Vas deferens moderately long, widened near penial sheath. Penis conical. Receptaculum seminis ovate, muscular.

Molecular data: A BLAST-n search of COI sequence resulted 99.85% identical to sequences of Aeolidia papillosa from the North-East Pacific (JX087536, KF643410) thus confirming the species identity of our samples.

Distribution: This species has a wide distribution in the boreal regions of the North Pacific and North Atlantic and also occurs in Arctic waters [the White and the Barents seas, see Kienberger et al., 2016]. Recent study highlighted that the presence of this species in Japan [ Baba, 1935] needs further confirmation [ Kienberger et al., 2016]. Since Baba’s specimens [1935] were also collected from Aniva Bay, our molecular results confirm the identity of this species in northwestern Pacific.