Phyllidia tula is a species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusk in the family Phyllidiidae.

Brunckhorst examined the type material kept at the US National Museum and additional material from Guam and redescribed the species in greater detail.

[3] This nudibranch has a black dorsum with large yellow-capped tubercles surrounded by pale blue or translucent white rings.

Towards the edge of the mantle these tubercles become small and scattered, sometimes without any yellow caps.

The underside of the foot is grey with a longitudinal black line.