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Dendrodoris denisoni

Species Profile

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Dendrodoris denisoni

Author: (Angas, 1864)

Order: Nudibranchia  Family: Dendrodorididae

Maximum Size: 80 mm

Sightings: Sunshine Coast


There is much ongoing discussion about the validity of the name Dendrodoris denisoni (Angas,1864).

We base our continuing use of the name Dendrodoris denisoni on a personal communication in 2013 from Bob Burn and added here with permission:
“….they [Valdes & Fahey, 2006] point out that Denrodoris denisoni is “most likely” a junior synonym of Actinodoris krusensternii J. E. Gray, 1850. Unlike the other Gray, 1850 senior synonyms that they discuss, they do not proclaim D. denisoni a nomen proctectum and A. krusensternii a nomen oblitum, leaving the way open for eventual use of the latter name in the event of a generic revision indicating a complex of species each needing a separate name. Until such time as the genus is revised, the status quo is to be maintained, that is Dendrodoris denisoni is the name to use for this species (especially when dealing with east coast Australian records).”

Valdes & Fahey, 2006 make the statement: “According to the external features and colour pattern, Actinodoris krusensternii is most likely a senior synonym of Dendrodoris denisoni (Angas,1864). [My emphasis]
There were two actions available to the authors that they have not taken:
– 1) They have not formally stated a synonymising of the two species with Dendrodoris krusensternii as the senior synonym.
– 2) Nor have they quashed Dendrodoris krusensternii as a nomen oblitum by applying ICN (1999, Article 23.9.2) whereby – a junior synonym (in this case Dendrodoris densoni) takes precedence over a senior synonym that has not been used since 1899, if the junior synonym has been used in at least 25 publications, published by at least 10 authors in the immediately preceding 50 years – as they have done with other long unused senior synonyms in the paper.

We note that Nimbs & Smith, 2021 have synonymised Dendrodoris gunnamatta Allan, 1932 with Dendrodoris krusensternii (Gray, 1850) through molecular sequencing. In using the name Dendrodoris krusensternii they have acknowledged that: “There remains some disagreement regarding the nomenclatural status of D. krusensternii, with some authors preferring to retain the name, Dendrodoris denisoni (Angus, 1864) ….” and that it is not the intention of their study:  “….to explore this matter, and the nomenclature used here follows WoRMS [1].

We acknowledge that the sequencing of both Japanese and eastern Australian specimens in Nimbs & Smith, 2021 is significant and portends an impact on any future generic revision of the Dendrodoris and subsequent nomenclatural reorganisation.

David A. Mullins – January 2024

– Valdés, Á. & Fahey, S. J. (2006). Dorid nudibranchs described by J. E. Gray in M. E. Gray, 1842-1857 (Mollusca: Opisthobranchia). Records of the  West. Australian Museum Supplement 2006, 69, 95–102.

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

– Nimbs, M. J. & Smith, S. D. A (2021). Genetic Evidence Confirms That the Porostomate Nudibranch Dendrodoris gunnamatta Allan, 1932 Is a Morphotype of Dendrodoris krusensternii (Gray, 1850) (Gastropoda: Nudibranchia). Taxonomy 2021, 1, 152–159. 

– MolluscaBase eds. (2024). MolluscaBase. Dendrodoris Ehrenberg, 1831. Accessed through: World Register of Marine Species [WoRMS] at: on 2024-01-05

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