Tenellia anulata (Baba, 1949)
Description
A small Aeolidacea, body length 5-10 mm. The rhinophores bear distinctive ring-like constrictions along their entire length — a key diagnostic feature. Cerata in 8-11 oblique rows per side: 1st row 3, 2nd 4, 3rd-7th 5-6 each, 8th 4, 9th 3, last rows 2 each. Right (and left) liver branches into 3-4 oblique rows. The genital orifice opens directly below the 2nd row on the right side; the anus opens just before the inner end of the 4th or 5th row; the nephroproct directly in front of the anus. Anterior foot corners rounded. The body is white, with yellow ceras tips and dark-brown central veins. The masticatory edge of the jaw plate bears a single row of 30-40 denticles. Radula formula 53×0.1.0. The central tooth bears 4-5 denticles on each side of the median cusp.Distribution
Type locality is off Kurosaki, Sagami Bay (600 m offshore, 12 m depth, August 1940, 1 specimen), off Kasago-ne at Sajima Island (16 m depth, August 1940, 2 specimens), and Hayama-Koiso, Sagami Bay (intertidal, August 1940, 1 specimen) — 4 specimens total. The original description (Baba, 1949) records the species only from Sagami Bay.Etymology
The specific epithet anulata is Latin for ringed. The original description does not give an explicit etymology paragraph; the descriptive sense reflects the ring-like constrictions on the rhinophores. The Japanese name "Tsuno-wa-mino-umiushi" (ringed-horn aeolid) likewise refers to the rings.Remarks
Originally described as Cratena anulata and later transferred to Tenellia. Described alongside Cratena venusta and Cratena pinnifera in the same monograph; distinguished from them by the ring-like constrictions of the rhinophores.References
- Tenellia anulata (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.
- ツノワミノウミウシ, 鈴木敬宇. (2000). ウミウシガイドブック〈2〉. TBSブリタニカ.
- ツノワミノウミウシ, 中野理枝. (2004). 本州のウミウシ. ラトルズ.
- ツノワミノウミウシ, 小野篤司 & 加藤昌一. (2009). ウミウシ. 誠文堂新光社.
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 Tenellia anulata
Same Genus Nudibranchs
Similar Colors Nudibranchs
Academic Database
Sea slug observation data is available in international marine biodiversity databases.