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Pretty similar are:
Phyllidia ocellata which is very variable in colour, but has usually a yellow-orange ground colour of the mantle, and has large black rings,
Phyllidia babai which has black rings at the base of some tubercles, and has a pale yellow mantle margin in some specimens,
Phyllidia willani which has longitudinal black swirls and a white granular appearance, and lacks orange pigment at the mantle margin
Phyllidia sp. 01 which has a pale yellowish-orange background colour
This specimen which I identified as Phyllidia willani has some faint orange pigment at the mantle margin, it might be also Phyllidia exquisita.
This specimen which I identified as Phyllidia exquisita has some faint orange pigment at the anterior mantle margin, and it has longitudinal black swirls, it might be as well Phyllidia willani.
I can't tell for sure how to distiguish the phyllidiids with the whitish granular appearance:
Phyllidia babai, Phyllidia exquisita, Phyllidia willani, Phyllidia sp. 01 and Phyllidia sp. 3 in IPN at page 292. I guess they are variants of one species.
Bill Rudman thinks Phyllidia babai, Phyllidia exquisita, and Phyllidia willani to be variants of the very variable Phyllidia ocellata.
More information on Phyllidia exquisita are on Bill Rudman's Sea-Slug Forum!