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I am pretty sure that the specimen #5 is a juvenile, it is rather small I guess 6 - 8 mm (no data had been recorded) because there is a picture of a very similar 10 mm specimen from Japan at the Mediterranean Slug Site.
This species was posted on 2 July 2003 at these websites as Nembrotha cf. purpureolineata O'Donoghue, 1924, changed on 17 August 2008 into
Nembrotha aurea Pola, Cervera & Gosliner, 2008.
More information on Nembrotha aurea are on Bill Rudman's Sea-Slug Forum!
How to cite:
Köhler, E. (2017), published 2 October 2017, Nembrotha aurea Pola, Cervera & Gosliner, 2008
available from https://www.Philippine-Sea-Slugs.com/Nudibranchia/Doridina/Nembrotha_aurea.htm