Ennoia briareus Bergh, 1896 Phyllodesmium briareum is a species of sea slug, an aeolid nudibranch, a marine gastropod mollusc in the family Facelinidae.

[1] The distribution of Phyllodesmium briareum includes Indo-Pacific and Australia.

[2] Phyllodesmium briareum uses camouflage and looks like the soft coral Briareum violacea with which it is often found.

This species contains zooxanthellae but has cerata of conventional aeolid shape.

[3][2] Phyllodesmium briareum is reported to feed on a number of species of briareid soft coral including Solenopodium stelleri and Briareum stecheri (sensu MacFadyen, 1936).