A broad ruffled mantle skirt with a maroon edge, carried in visible waves as it crawls.
A dorid to about 5 cm, the mantle cream to pale tan and finely speckled with brown, and the whole margin bordered by a band of red-brown to maroon. The gill plume and rhinophores carry the same pale ground and brown speckling. The shape is as much of a clue as the colour: Glossodoris have a broad, thin mantle skirt that is wider than the body beneath it and is held loose, so it ripples as the animal moves. The maroon border separates this one from the plain cream G. pallida, and from Doriprismatica atromarginata, which is white with a black margin and is a good deal more common on the same rubble.
Feeds on sponges and is found on or beside them, in the open, by day as well as at night. Recorded from about 3 to 30 m.
The skirt is rarely still, which is the practical difficulty with the animal: at the magnifications this size calls for, the margin is often the only part of the frame out of focus, and the moments worth waiting for are the ones when the slug has stopped and the skirt has settled into one plane. Animals sitting on a raised edge of rubble rather than flat on sand give a cleaner background.
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.
