Sagaminopteron nigropunctatum

Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Cephalaspidea
Family: Gastropteridae
Genus: Sagaminopteron
Species: Sagaminopteron nigropunctatum

Sagaminopteron nigropunctatum is a small batwing slug in the family Gastropteridae. Batwing slugs are headshield slugs, not true nudibranchs. They are named for the wide, wing-like flaps along the sides of the body, called parapodia.

The species is variable in colour, and Nudibranchs of the Philippines shows three varieties. The animal on this page is variety 3: an almost pure white slug with its parapodia folded up over the back, often in a cupped or ruffled shape.

Sagaminopteron species are usually found on or near the sponges they feed on. Because colour varies so much in this genus, the overall shape and the folded parapodia are good first clues, but compare your photo with all three varieties in the book before naming it.

This slug is only a few millimetres long and easy to miss. In the Philippines, slow searching over rubble and sponges, especially at night, gives the best chance of finding one. A dark background makes the white body stand out in photos.

It appears on page 310 of Nudibranchs of the Philippines.