Rostanga is a genus of sea slugs in the family Discodorididae.

[3] Some sources, such as The Sea Slug Forum still classify Rostanga in the family Dorididae.

The species from Japan and the Marshall Islands form the basal clade.

The species from the Atlantic Ocean and the Eastern Pacific from a clade that is a sister group to R. australis.

[4] Species within the genus Rostanga include: