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I label it for now Jorunna sp. 05, to distinguish it from other undescribed species of the genus Jorunna Bergh, 1876.
Jorunna sp. 05 is usually yellow with black spots, in some cases it can have a white background colour, and sometimes the black patches are replaced by scattered black caryophyllidia all over the mantle. Distinctive is a large black spot or line on the posterior tip of the foot, which the above specimen lacks.
More reseach is needed to to confirm the widespred Indo-Pacific distribution of these variants.
More information on Jorunna sp. 05 as Jorunna sp. 2 are on Bill Rudman's Sea-Slug Forum!