In Britain the body whorl has 15 to 23 costae on T. reticulata and 10 to 14 on T. nitida, but in the Adriatic the range on T. nitida is wider, 9 to 18, and overlaps with that of T. reticulata.
Left: 16 costae on T. nitida body whorl. Height 39.08 mm. Adriatic, Italy, September 2019. © J. Prkić.
Right: 12 costae on T. nitida body whorl. Height 19.4 mm. Blackwater, Essex, England, September 2019, leg. S. Taylor.