Chain of Chaetoceros borealis from net haul (0-50m depth), cruise AeN707 (Nansen Legacy project), station P5 on August 2019.
Cells and setae have many small chloroplasts. The chains are straight. Setae have a distinct basal part and the point of fusion is close to the chain edge. Upper and lower valves are similar (isovalvate). The windows are elliptical to hexagonal and the setae oblique or perpendicular to length axis of chain, often crossing each other. The terminal setae (end setae) have the same direction and length as the others and the windows are shorter than the cells.
Apical axis 12-46 um.
Throndsen, J., Hasle, G.R. and Tangen, K., 2007. Phytoplankton of Norwegian coastal waters. Almater Forlag AS. 341 pp.