Phyllidia dautzenbergi Vayssière, 1912 Phyllidiopsis bayi is a species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusk in the family Phyllidiidae.

[4] It is endemic to the southern Red Sea and the Gulf of Aden.

[5] This nudibranch has a translucent white dorsum with black lines creating a central ring with lines running off at right angles to the margin.

At the margin they widen slightly, giving the appearance of cut-off circular patches of white.

It is a small Phyllidiid, growing to 20 mm in length.