1: unpigmented, white head, sometimes with a thin black medial line.
2: single white line, sometimes with breaks, on cephalic tentacles.
3: yellow eye patches. 4: opercular lobe entirely pigmented black or dark brown. Left: shell height 2.5mm. Menai Strait. March 2012. Right: shell height 3.2mm. Llŷn Peninsula, Wales. March 2015.

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