Hypselodoris obscura (Stimpson, 1855)
Seasonally common in the Solitary Islands Marine Park, depending on available food source. Common throughout eastern and southern Australia. Known from New Guinea, Indonesia. In Australia recorded from Queensland and New South Wales.
Found in association with sponges, especially Dysidea sp. Depth from intertidal to at least 14 m.
Colour variation depending on geographic location, the bluish form as pictured common only in the northern part of its range. The more common greyish background colour is found throughout the species' range and more common in the south. May be more commonly found in siltier habitats. Grows to 60 mm.
Gary Cobb, David Mullins, Nudibranchs Encyclopedia, 2nd Edition, 2015. Publishers Thomas Slone, Masalai Press and Tim Hochgrebe, Underwater Australasia. p.148.
Australian Museum, Sea Slug Forum. http://www.seaslugforum.net/find/hypsobsc. Accessed 24/08/2018.