Author: (Baba, 1949)

Order: Nudibranchia  Family: Fionidae

Maximum Size: 12 mm

Sightings: Whitsundays

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Tenellia pinnifera (Baba, 1949)

A small aeolid nudibranch. The body is white or translucent white with numerous small white patches. The rhinophores are long and tapered and possess from 5 to 8, unusual and distinctive, semicircular ridges (incomplete annulae) along their length. Oral tentacles are long and tapered, being white with an orange/yellow band mid-length. The cerata are mostly translucent white with an opaque white band mid-length and an orange/yellow ring subapically, the very tip being opaque white. The digestive gland is visible through the translucent portions of each ceras as a brown tube. The anterior foot corners are rounded and the long tail, tapered, with white pigment dorsally.

Believed to feed on hydroids under shallow coral rubble.

Not a common species. Distribution is western and central Pacific – Japan across to Hawaii and down to the tropical east coast of Australia.

– Originally described as Cratena pinnifera from Japan.
– Some taxonomic sources use the name Catriona pinnifera. Other combinations previously used include: Cuthona pinnifera and Trinchesia pinnifera.
– It is possibly the Eubranchus sp. 03 of Marshall & Willan, 1999, whereby the low swelling mid-length on the cerata at the position of the opaque white band may have been misleading.

David A. Mullins – December 2023

References:
– ​Baba, K. (1949) Opisthobranchia of Sagami Bay collected by His Majesty The Emperor of Japan. Iwanami Shoten, Tokyo.

– Baba, K. (1961). Three new species of the genus Catriona from Japan (Nudibranchia-Eolidacea). Publications of the Seto Marine Biological Laboratory. 9(2): 367-372

– Gosliner, T. M. (1980 [“1979”]). The systematics of the Aeolidiacea (Nudibranchia: Mollusca) of the Hawaiian Islands, with descriptions of two new species. Pacific Science. 33(1): 37-77.

– Marshall, J. G. & Willan, R. C. (1999). Nudibranchs of Heron Island, Great Barrier Reef: A survey of the Opisthobranchia (sea slugs) of Heron and Wistari Reefs; Backhuys: Leiden, The Netherlands.

– Nagano, R. (2004). Opisthobranchs of Japan Islands. Rules Inc.

– Gosliner, T. M., Valde ́s, A ́. & Behrens, D. W. (2018). Nudibranch & Sea Slug Identification – Indo-Pacific, 2nd Edition. New World Publications, Jacksonville, Florida, USA.

– Pittman, C. & Fiene, P. (2023) Sea Slugs of Hawaii. At http://seaslugsofhawaii.com/species/Tenellia-pinnifera-a.html on 2023-12-29

– MolluscaBase eds. (2023). MolluscaBase. [WoRMS] Catriona pinnifera (Baba, 1949). Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=850651 on 2023-12-29