Eubranchus alexeii

• Main Authors: Ekimova, Irina A., Grishina, Darya Yu., Nikitenko, Ekaterina D.
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2024
• Subjects: Biodiversity; Taxonomy; Animalia; Mollusca; Gastropoda; Nudibranchia; Eubranchidae; Eubranchus; Eubranchus alexeii; Sakhalin
• Online Access: https://doi.org/10.5281/zenodo.11093316; http://treatment.plazi.org/id/038587BFA617DD30A879FC1AEA508B72

Eubranchus alexeii (Martynov, 1998) (Fig. 8A, H) Material studied: MIMB 48067, 1 specimen, dissected, Sea of Okhotsk, Aniva Bay, Moguchi River, Hirano ridge, 46°05’06.5”N, 142°12’39.4”E, 0.1–1 m in depth, on Zostera sp. with Obelia longissima colonies, 7 August 2023, coll. I. Ekimova, D. Grishina. Diagnosis: Body elongate, up to 4 mm in length, yellowish semitransparent with reddish-brown round spots. Rhinophores and oral tentacles elongated, smooth. Cerata finger-shaped, bearing thickening in middle part with digestive gland bulging, arranged in 5 rows with 2–3 cerata per row. Jaws rectangular, with masticatory border bearing one row of small conical denticles. Radular formula 29 × 1.1.1. Triangular rachidian tooth, central cusp cylindrical, with pointed tip, 4–6 lateral denticles on each side of cusp, innermost denticles smallest. Lateral teeth two times wider than rachidian teeth, with rectangular base, triangular cusp. Penis absent, copulative apparatus formed by everting atrium with complex stylet system. Molecular data : A BLAST-n search of COI sequences resulted in 99.17% identity to sequences of Eubranchus alexeii from GenBank thus confirming identification of the studied specimen. Distribution : Eubranchus alexeii was described and further mentioned as an endemic species of the Peter the Great Bay, northern Sea of Japan [Martynov, 1998; Martynov et al. , 2015b]. Subsequent works suggested it has wider geographic range at least in the Sea of Japan [Chichvarkhin, 2016, as Eubranchus misakiensis Baba, 1960]. Its discovery in Aniva Bay support this view and extends the known range of this species to southern parts of the Sea of Okhotsk. Published as part of 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, pp. 69-91 in Ruthenica, Russian Malacological Journal 34 (2) on page 82, DOI:10.35885/ruthenica.2024.34(2).3, http://zenodo.org/record/11042878