Nudibranch - Goniobranchus sp.

This one doesn't looks similar to Goniobranchus reticulatus which is a species more common in Philippines and South East Asia, it could be just a variation but am not certain. It has some similarity to Goniobranchus tinctorius but Goniobranchus tinctorius is supposedly not reported from tropical Indo-Pacific, but Red Sea and Oman.

Mentioned in Wikipedia for Goniobranchus tinctorius :

This species was described from the Red Sea. It also occurs in Oman. It has been reported widely in the tropical Indo-West Pacific but many of the records refer to Goniobranchus reticulatus, Goniobranchus alderi and similarly coloured, undescribed, species. Several of these have been shown to be distinct species by a DNA study.