Black with green-ringed orange spots, feeding openly on colonial sea squirts.
A polycerid to about 8 cm, black to very dark brown, patterned over the back with rounded orange-red spots each surrounded by a ring of pale green, and with orange rhinophores and gill plume. It is separated from Nembrotha kubaryana, which is larger and carries green ridges and an orange foot margin, and from N. cristata, which has green rather than orange on the gills.
Feeds on colonial ascidians and is found on or immediately beside a colony, usually with the oral tube everted into it. Like the rest of the genus it takes defensive compounds from the prey and is left alone, which is why an animal this conspicuous grazes in the open in daylight. Its own predator, when it has one, is another sea slug: Roboastra hunts Nembrotha. Recorded from about 5 to 30 m on the harder ground of a muck site rather than on open silt.
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.
