Separated from the other brown-mantled slugs by the band sequence at the mantle edge.
A firm dorid to about 9 cm, olive to grey-brown across the back and finely speckled with white, with a broad undulating mantle skirt that carries a fixed sequence of bands at the edge — a pale line, then a dark band, then a white to bluish-white rim. The gill plume and rhinophores are dark brown to black. Two other brown-mantled slugs share the same rubble. Doriprismatica atromarginata is cream rather than olive, softer in the body, and has a single black margin with nothing inside it; Glossodoris rufomarginata is smaller and paler with a maroon border and no dark band. The band sequence is the character to read, since the ground colour of all three varies too much to carry an identification on its own.
Feeds on thorectid sponges and stores scalaradial, a compound taken directly from the food and concentrated in glands around the mantle rim. Spawn is a cream ribbon of two or three whorls laid on or beside the sponge. It is one of the larger chromodorids on a muck site and moves in the open by day without any attempt at cover, which is the usual pattern for a slug carrying borrowed chemistry.
Recorded from about 5 to 35 m on sponge-covered rock, rubble and slope.
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.
