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

[2] This species was described from Laing Island, Papua New Guinea.

This nudibranch has a pale pink dorsum with white-capped compound tubercles in the middle part, reducing in size to single tubercles at the margin.

There are two narrow black lines which run in a wavy pattern between the tubercle groups, joining at the tail.

Connecting black lines run across the body and down the sides and there is a narrow black margin to the mantle.