In memory of our friend and colleague Luc Ector (1962–2022) and my husband Alan Orange (1955–2023) We investigated the type material of Berkella linearis, B. alpina, Frustulia saxonica, and F. crassinervia, and populations of these taxa and of F. vulgaris, F. quadrisinuata, F. erifuga, and F. amphipleuroides from Scotland and Wales with light and scanning electron microscopy. The species are distinguished from each other in light microscopy by differences in the shape of the valves, apices and central areas, and in scanning electron microscopy by differences in the raphe endings, striation and areola occlusions. Raphe curvature and the shape of the raphe endings vary within species currently in Frustulia and on this basis B. linearis might belong to Frustulia. However, a recent molecular analysis showed that several Frustulia taxa formed a separate lineage and further analysis is required to study relationships of species currently within Frustulia and whether some might belong to Berkella.