Bermudella japonica (Baba, 1949)
- Location
- Sokodo(Sanmata), Hachijo Island, Tokyo, Japan
- Date
- 2015/06/12
- Length
- 8mm
- Depth
- 6.0m
- Water temperature
- 16.7℃
Description
A small Okenia-related species, body length 5-8 mm, with a slug-shaped body and a long elongated tail. The mantle margin is sharply demarcated from the body sides; 7-9 simple club-shaped processes are arranged along each side margin (the posterior-most process is also simple, not bifid). No rhinophore sheath. Gills 5, simple, with only the anteromedian gill occasionally bifid; no gill pocket. The dorsum is smooth, but a single club-shaped process arises on the midline between the rhinophores and the gills. Oral tentacles large and leaf-like. The whole body is yellow-white, with albuminous fine dots scattered. Labial disc sheath-shaped, with irregularly shaped fibrous rodlets sparsely set on the surface. Radula formula 32-35×1.1.0.1.1. The innermost lateral teeth are large sickle-shaped with 18-20 small denticles along the side of the main cusp; outer teeth are small scale-shaped with bifid tips.Distribution
Type locality is off Hasaki, Sajima Island, Sagami Bay (17 m depth, August 1939) and Hayama-Choja-ga-saki and Hayama-Koiso, Sagami Bay (intertidal, August 1939, 3 specimens). The original description records the species from Sagami Bay and Kii.Etymology
The specific epithet japonica refers to Japan as the country of origin. The original description does not give an explicit etymology paragraph; the toponymic derivation is self-evident.Remarks
Originally described as Okenia (Okenia) japonica and later transferred to Bermudella. Distinguished from the related Okenia echinata by (1) the slug-shaped elongate body, (2) club-shaped (not conical, not bifid) papillae, (3) fewer gills (5), and (4) bifid tips on the outer lateral teeth. The Japanese name "Shiro-ibara-umiushi" (white-thorn sea slug) reflects the yellow-white ground colour and the numerous processes.References
- Bermudella japonica (Baba, 1949), Baba K. (1949). Opisthobranchia of Sagami Bay collected by His Majesty the Emperor of Japan (相模湾産後鰓類図譜). Iwanami Shoten, Tokyo. 4+2+194+7 pp., pls. 1-50.
- シロイバラウミウシ, 鈴木敬宇. (2000). ウミウシガイドブック〈2〉. TBSブリタニカ.
- 高岡生物研究会. (2002). 日本海のウミウシ. 第2版.
- シロイバラウミウシ, 中野理枝. (2004). 本州のウミウシ. ラトルズ.
- Okenia (Okenia) japonica Baba, 1949, Gosliner T. M. (2004). Phylogenetic Systematics of Okenia, Sakishmaia, Hopkinsiella and Hopkinsia (Nudibranchia: Goniodorididae) with descriptions of new species from the tropical Indo-Pacific". Proceedings of the California Academy of Sciences 55(5): 125-161.
- シロイバラウミウシ, 小野篤司 & 加藤昌一. (2009). ウミウシ. 誠文堂新光社.
- Paz-Sedano S., Moles J., Smirnoff D., Gosliner T.M. & Pola M. (2024). A combined phylogenetic strategy illuminates the evolution of Goniodorididae nudibranchs (Mollusca, Gastropoda, Heterobranchia). Molecular Phylogenetics and Evolution. 192: 107990. https://doi.org/10.1016/j.ympev.2023.107990
A Kindle field guide by the site author
Kimoto N. (2026). Sea Slugs of Japan & the Indo-Pacific, 2nd Edition.
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Photos of Bermudella japonica
Tag:
Same Genus Nudibranchs
Similar Colors Nudibranchs
Academic Database
Sea slug observation data is available in international marine biodiversity databases.