Rostanga lutescens, is a species of sea slug, a dorid nudibranch, a marine gastropod mollusc in the family Discodorididae.
This species was described from Timor, Indonesia. It has subsequently been reported from the Marshall Islands.
This dorid nudibranch is a pale, translucent orange or yellow in colour, and the dorsum is covered with caryophyllidia.
Most species of Rostanga feed on sponges of the family Microcionidae.