Dermatobranchus caeruleomaculatus

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

Thanks to Bernard Picton & Ron Silver to inform me and helping me on identifying this nudibranch

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Gosliner T.M. & Fahey S.J. (2011) Previously undocumented diversity and abundance of cryptic species: a phylogenetic analysis of Indo-Pacific Arminidae Rafinesque, 1814 (Mollusca: Nudibranchia) with descriptions of 20 new species of Dermatobranchus. Zoological Journal of the Linnean Society 161: 245–356.