Favorinus mirabilis Baba, 1955
- Location
- Ishikiri（Awa), Okinawa Island (Motobu and Northern area), Okinawa, Japan
- Date
- 2011/03/31
- Length
- 5mm
- Depth
- 10.0m
- Water temperature
- 21.0℃
Description
A small Aeolidacea, body length 15 mm. The rhinophores bear lamellae along their entire length, resembling Favorinus perfoliatus, but the present species is distinguished by having more numerous ceras groups and a markedly different colour. The cerata are simple fusiform, in 12 groups per side: 1st group 16, 2nd 18, 3rd 16, 4th onward gradually fewer (8-1). The first three groups are mounted on horseshoe ridges; the rest in oblique rows. Anterior foot corners tentaculiform. Genital orifice and anus in usual positions. Ground colour white, with the dorsum tinged yellow-brown and the cerata yellow-brown; each ceras has a single deep-purple spot just below the apex. The oral tentacles and the anterior margin of the foot are yellow; the rhinophores are dark brown. The masticatory edge of the jaw plate has the usual 3-4 rows of spinous teeth. Radula formula 21×0.1.0. The central tooth has smooth lateral edges.Distribution
Type locality is Hayama-Samejima and Hayama-Najima, Sagami Bay (intertidal, August 1949 and July 1952, 3 specimens). The original description (Baba, 1955) records the species only from Hayama in Sagami Bay.Etymology
The specific epithet mirabilis is Latin for marvellous or wonderful. The original description does not give an explicit etymology paragraph; the descriptive sense reflects the unusual coloration (deep-purple subapical spot on each ceras).Remarks
Resembles Favorinus perfoliatus in having lamellate rhinophores, but distinguished by (1) having 12 ceras groups (versus 6-7 in Favorinus perfoliatus) and (2) the yellow-brown body with a deep-purple spot just below the apex of each ceras.References
- ウツセミミノウミウシ（新稱）, 生物學御研究所編. (1955). 相模湾産後鰓類図譜〈補遺〉. 岩波書店.
- 高岡生物研究会. (2002). 日本海のウミウシ. 第2版.
- ウツセミミノウミウシ, 小野篤司. (2004). 沖縄のウミウシ. ラトルズ.
- ウツセミミノウミウシ, 中野理枝. (2004). 本州のウミウシ. ラトルズ.
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 Favorinus mirabilis
Same Genus Nudibranchs
Similar Colors Nudibranchs
Academic Database
Sea slug observation data is available in international marine biodiversity databases.