Cocconeis skvortzowii A–C raphe valve, external view C Lower valve (arrowhead) D–F sternum valve D, E external view F internal view. SEM A, C specimen No. BL15646, Island Bolshoy Ushkaniy B, D–F specimen No. BL15645, Island Bolshoy Ushkaniy. Scale bars: 3 µm (A, B, D); 5 µm (C); 6 µm (E); 8 µm (F).