Lyrella cassiteridum, a new species of marine epipelic diatom

Lyrella cassiteridum sp. nov. is described from the Isles of Scilly, SW Britain. It is an epipelic species and was found in samples taken from marine sandflats in the intertidal and uppermost subtidal zones. In LM, L. cassiteridum is most similar to L. abrupta , from which it can be distinguished by its larger size and coarser structure. The ultrastructure of the frustule is documented and discussed with respect to that of other Lyrella species and the related genus Petroneis. A brief review of the nomenclatural history of Lyrella is given.