Hypselodoris maritima (Baba, 1949)
- Location
- Tengan(Kombu), Okinawa Island (East coast), Okinawa, Japan
- Date
- 2015/05/16
- Length
- 12mm
- Depth
- 5.0m
- Water temperature
- 24.0℃
Description
A small Chromodorididae, body length about 1 cm. The dorsum is smooth, but the ventral mantle margin bears 13-20 small tubercles per side. Ground colour white. The central dorsum is largely covered with deep-blue longitudinal bands that curve and anastomose somewhat irregularly between individuals, producing a flowing-pattern (ryūmon) appearance. The mantle margin is bordered by a double band: blue (outer) and yellow (inner). Similar double bands occur along both sides of the tail tip. Rhinophores and gill leaves orange. A continuous deep-blue band runs around the entire foot at the boundary between the foot and the lateral body wall. Radula formula 45×25-30.0.25-30. The first lateral has three cusps; the rest of the laterals have two cusps each.Distribution
Type locality is Hayama-Koiso, Sagami Bay (intertidal, August 1939 and July 1940, 2 specimens) and Hayama-Najima, Sagami Bay (intertidal, August 1939 and August 1940, 3 specimens). The original description (Baba, 1949) records the species only from Sagami Bay.Etymology
The specific epithet maritima is Latin for of the sea. The original description does not give an explicit etymology paragraph. The Japanese name "Ryūmon-iro-umiushi" (flowing-pattern colour sea slug) refers to the wave-like deep-blue dorsal band pattern.Remarks
Originally described as Glossodoris maritima and later transferred to Hypselodoris. Differs from Hypselodoris placida (described in the same monograph) by its smaller size, the flowing-pattern deep-blue dorsal band system, the continuous blue-outer / yellow-inner double bands at the mantle and tail margins, and the deep-blue band running around the entire foot.References
- Hypselodoris maritima (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.
- Hypselodoris maritima (Baba, 1949), Gosliner T.M. & Johnson R.F. (1999). Phylogeny of Hypselodoris (Nudibranchia: Chromodorididae) with a review of the monophyletic clade of Indo-Pacific species, including descriptions of twelve new species. Zoological Journal of the Linnean Society. 125: 1-114. https://doi.org/10.1111/j.1096-3642.1999.tb00585.x
- リュウモンイロウミウシ, 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.
- リュウモンイロウミウシ, 小野篤司. (2004). 沖縄のウミウシ. ラトルズ.
- リュウモンイロウミウシ, 中野理枝. (2004). 本州のウミウシ. ラトルズ.
- リュウモンイロウミウシ, 小野篤司 & 加藤昌一. (2009). ウミウシ. 誠文堂新光社.
- Hypselodoris maritima, Johnson R.F. & Gosliner T.M. (2012). Traditional taxonomic groupings mask evolutionary history: a molecular phylogeny and new classification of the chromodorid nudibranchs. PLoS ONE 7(4): e33479.
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 Hypselodoris maritima
Tag:
Same Genus Nudibranchs
Similar Colors Nudibranchs
Academic Database
Sea slug observation data is available in international marine biodiversity databases.