Pseudo-nitzschia seriata
No picture so far.
Forms stepped chains. Two chloroplasts, one in each end, are seen in the cells. The cells are lanceolate and slightly asymmetrical, with one straight and one convex side, in valve view. In girdle view they are lanceolate with pointed ends. The valves have an eccentric raphe and lack a central nodule, and approximately an equal number of striae and fibulae. Each stria has 2-4, usually 4, rows of poroids. Each cingulum has three bands.
Apical axis (heteropolar) 91-180 µm, transapical axis 4.6-8.0 µm, 14-20 striae and fibulae in 10 µm, 6-8 poroids in 1 µm. First girdle band with 21-24 band striae in 10 µm, each being 2-3 poroids high and 4-6 poroids wide.
P. seriata can be confused with P. obtusa, but P. obtusa has shorter cells, is less pronounced asymmetrical in valve view, and has a narrower valve compared to P. seriata. P. obtusa has 2 rows of poroids in contrast to 2-4 rows in P. seriata. Finally, P. obtusa has a higher density of girdle band striae.
Hasle GR & Lundholm N. 2005. Pseudo-nitzschia seriata f. obtusa (Bacillariophyceae) raised in rank based on morphological, phylogenetic and distributional data. Phycologia 44:608-619.
Throndsen J. Hasle G.R. and Tangen K. 2007. Phytoplankton of Norwegian coastal waters. Almater Forlag AS. 341 pp
In colder waters in northern temperate areas.