Often taken for a phyllidiid on the rubble until the gill plume is seen.
A small dorid to about 3 cm, the mantle white to cream with irregular dark green to near-black patches and a scatter of low rounded tubercles, the whole edged by a fine pale margin. On rubble it is regularly taken for one of the phyllidiids, and the mistake is a reasonable one — the colour scheme and the bumpy back are much the same. The check that settles it is the gill plume. This animal has one, a retractable rosette at the rear of the mantle, and Phyllidia and Phyllidiella have none at all, breathing instead through folds underneath the mantle edge. A photograph taken from directly above will usually show it.
Long placed in Chromodoris, and most guidebooks in circulation give it as Chromodoris geometrica; the chromodorids were split across several genera in a revision that moved this and many similar animals into Goniobranchus.
Feeds on sponges. At 3 cm, mottled dark on pale, and sitting on rubble that is itself mottled dark on pale, it is a species found by recognising the pattern rather than by spotting the animal, and it is easy to swim over. Recorded from about 3 to 25 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.
