Hypselodoris lacuna

Hypselodoris lacuna is a small nudibranch characterized by its opaque white body, which features round transparent patches with black or grey spots at their centers. The mantle is further adorned with small blue-grey spots along its edge, while the gills display orange pigment lines on their outer surfaces. The rhinophores are distinct with their orange-brown clubs and translucent bases. This species can grow to a total length of at least 12 mm, making it relatively small compared to other nudibranchs. This nudibranch was first described from Tingloy in the Philippines and has a wide distribution across the western Indian Ocean and western Pacific, including regions such as Aldabra Atoll, Vanuatu, Indonesia, Papua New Guinea, and Japan. It is commonly found in shallow waters, with all recorded sightings occurring at depths less than 40 meters, and the majority at depths under 30 meters. Hypselodoris lacuna typically resides in environments like coral reefs and rocky areas. Feeding primarily on small invertebrates, Hypselodoris lacuna grazes on algae and other organic materials. While specific breeding behaviors are not detailed, nudibranchs are generally known for their hermaphroditic reproductive strategies. Divers may find it intriguing to encounter this nudibranch, as its unique coloration and patterns stand out against the backdrop of its reef habitat. The conservation status of Hypselodoris lacuna is not evaluated in the sources, leaving its current risk level unclear.