Loch's Chromodoris

"Chromodoris lochi is blue or blueish-white with typically three dark or black longitudal lines running down the body. Individuals can reach at least 34 mm in length. There is some variation between individuals in this species, and the gills and rhinophores range in color from a translucent straw-color, through to pink and light orange.
This species is very similar in appearance to Chromodoris willani, Chromodoris boucheti and Chromodoris dianae and can be difficult to tell apart. Its most distinguishing feature is the uniform coloring of the mantle and the lack of white specks which are present in some of the other species."

Source : http://en.wikipedia.org/wiki/Chromodoris_lochi