Click the thumbnail photos to enhance!
Pretty similar are:
Phyllidiopsis phiphiensis which has black rhinophores, 2 low white ridges on the mantle with a white mantle margin with black spots and 3 black lines. This species was first reported from the Phi Phi Islands, Thailand and not yet from the Philippines.
Phyllidiopsis sphingis which has white rhinophores, 3 low white ridges on the mantle with an iridescent blue broad margin and 4 black lines with black rays extending to the mantle edge. The 2 median black lines unite between the rhinophores.
Phyllidiopsis xishaensis which has translucent straw-coloured rhinophores, 3 low white ridges on the mantle with a white margin and 4 black lines. The 2 median black lines unite between the rhinophores. Sometimes there are also black spots at the white mantle margin.
More information on Phyllidiopsis annae are on Bill Rudman's Sea-Slug Forum!