Click the thumbnail photos to enhance!
I have posted more pictures than usual to show this colour variant with its salmon pink egg mass.
Pretty similar are:
Thorunna australis which has a pale bluish or pink background colour, two longitudinal white lines, one on either side of the mantle and always one reddish band on the rhinophores,
Mexichromis aurora which differs by three wide whitish yellow longitudinal bands each outlined with opaque white, and by purple or blue spots between the bands and near the margin, and by small opaque white submarginal spots,
Thorunna cf. florens which differs by two broad dark pink longitudinal bands, outlined in opaque white, by orange rhinophores with a white spot, and by a transverse orange patch on the front of the mantle.
More information on Hypselodoris maculosa are on Bill Rudman's Sea-Slug Forum!