Rostanga elandsia, is a species of dorid nudibranch.

It is a marine gastropod mollusc in the family Discodorididae.

This species has so far only been found around the southern African coast from the Atlantic side of the Cape Peninsula to the eastern side of False Bay.

It has been found from the mid-intertidal zone to at least 30 m.[1][2] It is endemic to South Africa.

[3][4] This species feeds on red and yellow-orange sponges which determine the animal's colour.