Dermatobranchus pustulosus

Order : NUDIBRANCHIA
Suborder: DEXIARCHIA
Infraorder : CLADOBRANCHIA
Parvorder : EUARMINIDA
Superfamily : ARMINOIDEA
Family : Arminidae

Dermatobranchus pustulosus can be distinguished from other arminaceans by its brownish mottled mantle with a series of irregular pustules. The rhinophores are very bulbous. The foot and the oral veil are pink edged with black spots.
In this specimen are the rhinophores not very bulbous, but it looks very similar to the specimen in IPN at page 308, except of the rhinophores:
Gosliner, Terrence M., David W. Behrens & Ángel Valdés. 2008. Indo-Pacific Nudibranchs and Sea Slugs. Sea Challengers Natural History Books.
Gig Harbor, Washington. 426 pp.
It was originally posted at these websites as Dermatobranchus sp. B.
Pretty similar is Dermatobranchus tuberculatus, which has also an irregular body surface, and differs by the tan mantle, by the flat rounded tubercles, and by the rhinophores.