Body much broader than Aeolidiella sanguinea.

Much opaque pigment on dorsum, rhinophores and cerata. Little translucency; internal eyes not visible. Dull whitish cnidosacs visible in cerata. Distance between oral tentacles about three times thickness of tentacle base.

Length 26 mm, Mersey Estuary, England, October 2010. Anterior edge of foot, in ventral view, a smooth crescent terminating in short triangular propodial tentacles.  From Alder and Hancock (1845-1855) Family 3 Plate 9 (A. papillosa sensu lato).