Egg capsule of T. reticulata is initially like a flat brandy bottle with circular body, and ova fill <50% of it (top left). After 1 or 2 months it broadens and ova have grown to fill it (bottom left). W/H 80% including neck when recently laid, mean H. 4.07 mm, W. 3.25 mm (Roland & Luque, 1994).

Capsules of T. nitida are slenderly ovoid, even when case broadens late in development. W/H 65% including neck when recently laid, mean H. 2.65 mm, W. 1.72 mm (Roland & Luque, 1994).

Left: T. reticulata, Anglesey, Wales, May 2016. Right: T. nitida, Oosterschelde, Netherlands, August 2019, © B. van der Sanden

Capsules of T. nitida are slenderly ovoid, even when case broadens late in development. W/H 65% including neck when recently laid, mean H. 2.65 mm, W. 1.72 mm (Roland & Luque, 1994).

Left: T. reticulata, Anglesey, Wales, May 2016. Right: T. nitida, Oosterschelde, Netherlands, August 2019, © B. van der Sanden