Ceratosoma bicolor Baba, 1949
- Location
- Short coral garden, Oobiki Island, Nagasaki, Japan
- Date
- 2017/10/07
- Length
- 20mm
- Depth
- 15.0m
- Water temperature
- 24.0℃
Description
A medium-sized Ceratosoma, total length about 65 mm. Smaller than Ceratosoma cornigerum but with an essentially identical body shape. The coloration is monotone: ground colour pale violet, with darker violet narrow edge lines along the mantle and foot margins. A single vermilion longitudinal stripe runs along the dorsal midline from between the rhinophores to just in front of the gills. The dorsum of the tail bears a vermilion reticulate pattern. Rhinophores, gill leaves, and the tongue-like posterior mantle process are all tinged vermilion. Labial-disc fibres single-tipped. Radula formula 48×58-65.0.58-65 — narrower than that of Ceratosoma cornigerum but with somewhat more denticles per lateral. The first lateral has 1 inner denticle and 3-4 outer denticles flanking the median cusp; from the second lateral onward, 2-3 denticles are arranged along the outer edge.Distribution
Type locality is Amanawa-ba, Sagami Bay (100-350 m depth, July-August 1935, 2 specimens) and off Kameshiro-shō, Sagami Bay (80-90 m depth, August 1935, 2 specimens). The original description records the species only from deeper waters of Sagami Bay.Etymology
The specific epithet bicolor is Latin for two-coloured. The original description does not give an explicit etymology paragraph; the descriptive sense reflects the two-colour contrast (pale violet ground with vermilion median stripe). The Japanese name "Futa-iro-nishiki-umiushi" (two-colour brocade sea slug) likewise refers to the two-colour scheme.Remarks
Distinguished from Ceratosoma cornigerum by smaller size, monotone pale-violet ground with only a vermilion median dorsal stripe (versus the orange-yellow / red-violet pattern of Ceratosoma cornigerum), narrower radula. Found at notably deeper water (80-350 m) than typical shallow-water chromodorids.References
- Ceratosoma bicolor 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.
- 馬場菊太郎. (1989). 日本産ニシキウミウシ属の再検討. 貝類学雑誌. 48(3): 141-149. https://doi.org/10.18941/venusjjm.48.3_141
- フタイロニシキウミウシ, 益田一. (1999). 海洋生物ガイドブック. 東海大学出版会.
- フタイロニシキウミウシ, 益田一. (1999). 海洋生物ガイドブック. 第2刷. 東海大学出版会.
- フタイロニシキウミウシ, 鈴木敬宇. (2000). ウミウシガイドブック〈2〉. TBSブリタニカ.
- ニシキウミウシ, 中野理枝. (2004). 本州のウミウシ. ラトルズ.
- Ceratosoma bicolor, Helmut Debelius, Rudie H. Kuiter. (2007). Nudibranchs of the World.
- Ceratosoma bicolor, 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.
- ニシキウミウシ, 中野理枝. (2018). 日本のウミウシ. 文一総合出版.
Featured in this book
中野理枝. (2019). 日本のウミウシ. 第二版. 文一総合出版.
文一総合出版
This species, Ceratosoma bicolor, is included in the book.
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Same Genus Nudibranchs
Similar Colors Nudibranchs
Academic Database
Sea slug observation data is available in international marine biodiversity databases.