Specimen with typical A. papillosa features of dense dark pigment on head, on nearly full length of rhinophores and on part of cerata. It lacks any sign of the white Y on the head which many recorders associate with A. filomenae. But the broad, flattened, tapering-distally cerata with much of the digestive gland visible, are typical of A. filomenae. As well as the whitish translucent truncated tip of the rhinophores, there is a small apical band of light opaque pigment which is usually absent from A. papillosa and larger on A. filomenae. The bright yellow notum is unusual on both species. It cannot be confidently identified to species without molecular sequencing and is best recorded as Aeolidia sp.

On this specimen the usually concealed, white, left flank is exposed by loss of cerata. It shows the diagonal attachment lines of the missing cerata. Individual is on muddy sand eating a sea anemone.
South-west Sweden. February 2022. © E. Burman.