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The specimen #2 has lost its 'tail', this is possibly the reason why it is not on its food source.
Very similar is Oxynoe viridis (Pease, 1861) which differs by blue spots and by white papillae.
It is reported to feed on Caulerpa racemosa algae.
How to cite:
Köhler, E. (2018), published 20 March 2018, Oxynoe sp. 02 Genus: Rafinesque, 1814
available from http://www.Philippine-Sea-Slugs.com/Sacoglossa/Oxynoe_sp_02.htm