Click the thumbnail photos to enhance!
It is most probably Goniodoridella sp. 7 in IPN at page 128:
Gosliner, Terrence M., David W. Behrens & Ángel Valdés. 2008. Indo-Pacific Nudibranchs and Sea Slugs. Sea Challengers Natural History Books.
Gig Harbor, Washington. 426pp.,
though it seems to lack the median black patch in front of the rhinophores.
Pretty similiar is:
Goniodoridella sp. 01 which differs by the black line running down from the 'crescent' at the sides in a posterior slant.