Aeolidiella alderi
Body translucent with no opaque marks. No white ‘Y’ or triangular mark on head.
Cerata not flattened; have uniform diameter for most of length, colour varies with diet.
Apices of cerata are white or pale. Rhinophores translucent, no dark pigment marks.
Internal eyes visible at base of rhinophores. Distance between oral tentacles at base about same as thickness of single tentacle base.
Length 8.8 mm. Menai Strait, Wales. September 2015