P. radiata from Croatian Adriatic. Dark lines in grooves thinner than on P. inconspicua and some are obliquely orientated. P. radiata is not on the U.K. Species Inventory, but it has been suggested (H. Raven, 2023. pers. comm. 9 April) that the live Welsh specimens in this account are it. Left: shell height 4 mm, © J. Prkić. Right: height 2.4 mm, 2019, det. J. Prkić, ‘probable’. © P. Ugarković.