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Pretty similar are:
Cratena sp. 01 which lacks the orange/red patches on the head and lacks white lines on the notum, and differs by white and a few orange spots on the body.
Cratena cf. lineata A which lacks of opaque white longitudinal lines on the notum,
Cratena cf. lineata B which differs by a translucent orange backgound colour and lacks the orange/red patches in front of the rhinophores.
Let me quote IPN: "Additional study is needed to determine whether individuals without lines on the notum represent a distinct species."
I like to add to this statement those specimens which lack the orange/red patches in front of the rhinophores.
Gosliner, Terrence M., David W. Behrens & Ángel Valdés. 2008. Indo-Pacific Nudibranchs and Sea Slugs. Sea Challengers Natural History Books.
Gig Harbor, Washington. 426pp.
More information on Cratena lineata are on Bill Rudman's Sea-Slug Forum!
How to cite:
Köhler, E. (2016), published 23 May 2016, Cratena lineata (Eliot, 1905)
available from https://www.Philippine-Sea-Slugs.com/Nudibranchia/Cladobranchia/Cratena_lineata.htm