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Let me quote Marcela Bolanos at LifeDesks:
"External anatomy: Thick body without ruffled margins. The background is black with velvety appearance with a bright blue narrow band near to margin and an extremely white line at rim, sometimes yellow or turquoise. The ventral surface is black with the white rim. Pseudotentacles formed by simple broad folds of the anterior margin but the pseudotentacular eyes are not visible because of the dark pigment."
How to cite:
Köhler, E. (2017), published 27 March 2017, Pseudoceros sapphirinus Newman & Cannon, 1994
available from https://www.Philippine-Sea-Slugs.com/Look-alike/Platyhelminthes/Pseudoceros_sapphirinus/Select.htm