Rostanga orientalis is a species of dorid nudibranch (marine gastropod mollusc) in the family Discodorididae.

This species was described from Hoi Ha, Hong Kong.

It had previously been reported from Japan, but was misidentified as Rostanga muscula.

[2] This dorid nudibranch is red, and the dorsum is covered with caryophyllidia; it is very similar to other species of Rostanga.

[1] Most species of Rostanga feed on sponges of the family Microcionidae.