This goniodorid nudibranch is translucent white in color with orange lines on the body. There is a mid dorsal line and lines along the pallial margin, which may be continuous or interrupted. The pre-rhinophoral papillae and gills are tipped with orange and there is a line of orange pigment along the ridge of the tail. There are 4-14 club-shaped extra-branchial papillae which are translucent white with orange or yellowtips. Small papillae with orange tips typically occur between larger papillae with pale yellow tips. Individuals without the lines on the body occur in some populations. Although currently considered to be a synonym of the European species Ancula gibbosa there are significant differences in color and shape of the extra-branchial papillae and this is probably a distinct species.