Goniobranchus setoensis

Goniobranchus setoensis is a translucent white nudibranch adorned with opaque white lines and purple spots. It features a sub-surface margin of orange-red, a white line encircling the center of its back, and a distinctive line that runs from between its rhinophores to the middle of its back, dividing to loop around the gills. The outer edge has a row or double row of purple spots without a white halo, and small white spots can be found along the mantle edge. This species can be found in the central Indo-Pacific region, ranging from Japan to Sri Lanka, and extending to the Marshall Islands and Kiribati. It typically inhabits shallow waters, with all recorded occurrences being shallower than 40 meters, and 90% below 20 meters. Goniobranchus setoensis feeds primarily on sponges from the family Aplysillidae. Breeding behavior and specific reproductive details are not well-documented. Encounters with this nudibranch during dives can be intriguing, as divers may observe its unique coloration and patterns against the backdrop of the reef. The species has not been evaluated for conservation status.