Distribution: Probably at the southernmost limit of distribution in the Solitary Islands Marine Park. Widespread but at no time common. Found in Tanzania and Indo-West Pacific.

Ecological Notes: Often found in pairs, crawling one after the other, on reefs to a depth of 25 m. Feeds on sponges, in particular Dysidea fragilis.

Additional Notes: The mottled light and dark tan body with spots and blue/purple marginal band is very similar to Goniobranchus leopardus but the purple/blue spots on H. tryoni are more numerous and solid in colour. Grows to 90 mm.

References: Gary Cobb, David Mullins, Nudibranchs Encyclopedia, 2nd Edition, 2015. Publishers Thomas Slone, Masalai Press and Tim Hochgrebe, Underwater Australasia. p.152.