Author: Eliot, 1913

Order: Nudibranchia  Family: Tethydidae

Maximum Size: 500 mm

Sightings: Sunshine Coast

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Melibe japonica Eliot, 1913

Melibe japonica is encountered from time to time on the Sunshine Coast in marinas being observed by the live-aboard residents or those that work in or around them. They are only seen as they float through on the tide, the reason for them being off the substrate unknown. They are also noticed in canals, washed up on beaches following rough weather and at times as commercial fishing trawler by-catch.

It is an extremely large species described as “colossal” in its redescription by Baba. Pink in colour with the edge of the oral veil and extremities of the cerata of a darker hue. The oral veil, foot and detachable cerata are all large. Rhinophores and sheaths are small. Tubercles on the large oral hood are stubby and scattered while those on the body midline are dendritic. Cerata are paddle-like and readily autotomised.

It crawls across the substrate feeding by casting its circular oral hood over the substrate to trap crustaceans beneath. The edge of the oral hood is lined with rows of sensory papillae. It does swim, by strong flexions of the body, but the reason for that other than as an escape mechanism is unknown.

May reach up tp 500 mm in size.

Sometimes referred to by the common name of Japanese Hooded Nudibranch.

Melibe mirifica (Allen, 1932) is synonym.

The World Register of Marine Species (WoRMS) lists the name Melibe japonica Eliot, 1913 as unaccepted, the reason being stated as “uncertain synonym” and quoting Gosliner & Smith 2003, as the source of synonymy. However, Gosliner & Smith 2003 do not make a compelling case for the synonymy and do not actually formally synonmize it. Su-Jeong Yang et al 2018, state that Melibe japonica is most closely related to Melibe viridis and show them as two separate species in a phylogenic tree constructed from COI sequences.

David A. Mullins – November 2021

References:
– Kelaart, E. F. (1858). Description of new and little known species of Ceylon nudibranchiate molluscs, and zoophytes. Journal of the Ceylon Branch of the Royal Asiatic Society. 3: 84-139.

– Alder, J. & Hancock, A. (1864). Notice of a collection of nudibranchiate Mollusca made in India by Walter Elliot Esq., with descriptions of several new genera and species. Transactions of the Zoological Society of London. 5: 113-147.

– Eliot, C. N. E. (1913). Japanese nudibranchs. Journal of the College of Science, Imperial University Tokyo. 35: 1-47.

– Allan, J. K. (1932). A new genus and species of sea-slug, and two new species of sea-hares from Australia. Records of the Australian Museum, 18(6): 314-320.

– Baba, K. (1949). Opisthobranchia of Sagami Bay collected by His Majesty The Emperor of Japan. Iwanami Shoten, Tokyo. 194pp., 50 Pls.

– Gosliner, T. M. (1987). Review of the nudibranch genus Melibe (Opisthobranchia: Dendronotacea) with descriptions of two new species. The Veliger 29(4): 400-414.

– Gosliner, T. M. & Smith, V. G. (2003). Systematic review and phylogenetic analysis of the nudibranch genus Melibe (Opisthobranchia: Dendronotacea) with descriptions of three new species. Proceedings of the California Academy of Sciences. 4(54): 302-356.

– Rudman, W. B., (2004, January 28). Melibe japonica Eliot, 1913. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/melijapo and associated messages.

– Su-Jeong Yang, Hyunjung Seo, Seok-Gwan Choi, Sangdeok Chung & Hyun- Woo Kim (2018). Characterization of the complete mitochondrial genome of Melibe japonica (Eliot, 1913) collected from Korean water, Mitochondrial DNA Part B, 3:2, 1057-1058

– MolluscaBase eds. (2021). MolluscaBase. Melibe japonica Eliot, 1913. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=593363 on 2021-10-31.