Melibe arianeae is a species of sea slug, a nudibranch, a marine gastropod mollusc in the family Tethydidae.

It tapers posteriorly to form a long and conical shape to the end of the foot.

It and the cerata and rhinophoral sheaths are completely covered with multiple, tiny tubercles that are white and opaque.

The cerata are mainly warty in appearance due to complete coverage of small tubercules.

They are oval and are inflated with their distal ends being bifurcate or trifurcate, or, simple.