White and velvety with black rings, feeding on a blue sponge that makes it worth studying.
A dorid to about 6 cm, chalk white with clusters of black rings and blotches arranged over the back, and a surface covered in caryophyllidia — minute stalked papillae tipped with spicules — which give the animal a matt, velvety texture rather than a smooth one. The rhinophores and the gill plume are black-tipped and retract completely into pockets.
It feeds on the blue sponge Xestospongia, which contains renieramycins, and the slug sequesters those compounds; a related molecule, jorumycin, was described from this species and the group has been worked on as a source of anticancer leads. That is worth stating carefully: the chemistry is real and published, and it does not make the animal medicine. Found on and beside the food sponge, and a slug on open rubble is usually within a metre of one. Recorded from about 3 to 30 m.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
