Palio nothus is a species of sea slug, a nudibranch, a shell-less marine gastropod mollusc in the family Polyceridae.

[3] This species was described from Prestonpans Bay, Firth of Forth, Scotland.

It has subsequently been reported from the United Kingdom north to Scandinavia, Russia and Greenland.

[4] In the north-east Atlantic Palio nothus feeds on bryozoans of the genus Bowerbankia.

[5] Its eggs are laid in a short ribbon-like spiral.