Chromodoris westraliensis (O'Donoghue, 1924)

Description

A medium-sized chromodorid reaching about 65 mm in length. Background colour black with one or two vivid blue dorsal patches finely speckled with darker dots, the whole bordered with an orange marginal band. Rhinophores and gills are deep orange-red. The position of the black band relative to the orange margin and the presence of a median black patch vary among individuals.

Distribution

Endemic to Western Australia, recorded from the Kimberley region in the north to Esperance in the south, including the Abrolhos Islands (type locality), Rottnest Island, Cervantes, Exmouth, and Ningaloo. Particularly abundant in the Perth region. Found on shallow partially exposed reefs down to about 18 m.

Etymology

The specific epithet westraliensis is a toponymic adjective derived from "Westralia", a colloquial abbreviation of Western Australia, meaning "from Western Australia".

Remarks

The species feeds on a single sponge species and sequesters host-derived secondary metabolites for defence; the bright colouration is interpreted as an aposematic signal.

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References

• Glossodoris westraliensis n.sp., O'Donoghue C.H. (1924). Report on Nudibranchiata from the Abrolhos Islands, Western Australia, with description of a new parasitic copepod. Journal of the Linnean Society of London, Zoology, 35(237): 521-579, plates 27-30.
• Chromodoris westraliensis, Johnson R.F. & Gosliner T.M. (2012). Traditional taxonomic groupings mask evolutionary history: a molecular phylogeny and new classification of the chromodorid nudibranchs. PLoS ONE 7(4): e33479.
• Chromodoris westraliensis, Layton K.K., Gosliner T.M. & Wilson N.G. (2018). Flexible colour patterns obscure identification and mimicry in Indo-Pacific Chromodoris nudibranchs (Gastropoda: Chromodorididae). Molecular Phylogenetics and Evolution. 124: 27-36. https://doi.org/10.1016/j.ympev.2018.02.008
• Chromodoris westraliensis, Terrence Gosliner, Ángel Valdés and David Behrens. (2018). Nudibranch and Sea Slug Identification Indo-Pacific 2nd Edition. New World Pubns Inc.