Rostanga muscula

Rostanga muscula is a species of sea slug, a dorid nudibranch, a marine gastropod mollusc in the family Discodorididae.

Distribution
This species is endemic to New Zealand.

Description
This dorid nudibranch is bright orange to reddish-orange, and the dorsum is covered with caryophyllidia; it is very similar to other species of Rostanga.

Ecology
This is a common intertidal species. It feeds on the red sponge, Microciona coccinea (family Microcionidae). It is also found to eat the introduced sponge, Ophlitaspongia seriata (=Ophlitaspongia papilla) and the native Holoplocamium neozelanicum