This is the one somebody called beautiful, and its close relative on this reef is the one somebody called unadorned. Eliot named this species in 1904; the other waited until 2002 for a name that amounts to a shrug. Both judgments are now permanent.
On the animal itself the useful thing is the two-tone construction. The center of the back is red to salmon, blotched darker, with irregular opaque white patches scattered across it. The margin is distinctly paler, running lilac to purple-brown, and the change between the two happens as a zone rather than as a line. On sand or rubble at night the effect is not a slug but a lump of encrusting sponge that happens to be sitting on the bottom.
Underneath it is a Platydoris and built like one: mantle thin, stiffened with mineral spicules, hard to the touch and held pressed down flat with no raised edge for a predator to start on. That mechanical defense sits on top of the chemical one it takes from the sponges it grazes.
Five centimeters (2 in), out after dark, under something during the day.
It is one of the least recorded animals in this section, with under ten logged observations in the world, most of them from 🇰🇪 Kenya and the 🇲🇿 Mozambique Channel.
- red to salmon center with darker blotches and irregular white patches
- margin distinctly paler than the center, lilac to purple-brown
- low, flat and hard, sitting like a piece of encrusting sponge
- five centimeters
