"I would have identified this nudibranch as Risbecia godeffroyana too if I didn’t know where it was from. But because it comes from Hawaii and because nobody has studied the comparative anatomy of that species and compared it with specimens from the western Pacific Ocean (presently called godeffroyana) and hence concluded they are separate or different species, then we are obliged to call it R. imperialis for now. In fact, if they are the same species, then it will have to take the name R. imperialis anyway because imperialis was published in 1860 and godeffroyana in 1877."