typically forms chains of up to 16 cells but chains with up to 64 cells have been reported. The cingulum is descending (displaced up to 20 % of cell length). The sulcus extends from the antapex to the apex, which is surrounded by an apical groove. It runs in a counter-clockwise direction around the apex and starts at the end of the intrusion of the sulcus into the epitheca. Cells contain many chloroplasts and have a large centrally placed nucleus. Cysts are round (42-52µm), brown and reticulated.
Tomas C ed. (1996) Identifying marine diatoms and dinoflagellates. pp 598. Academic Press Ltd. London
Hallegraeff GM and Hara Y (2003) Taxnomy of harmful marine raphidophytes. In: Hallegraeff GM, Anderson DM, Cembella AD. Manual on harmful microalgae. UNESCO Publishing