PSEUDO-NITZSCHIA AS A GENUS DISTINCT FROM NITZSCHIA (BACILLARIOPHYCEAE)

Morphologic, diagnostic characters of the subgenus Nitzschia, genus Ni tzschia Hassall 1845, and the marine planktonic genus Pseudo-nitzschia H. Peragallo in H. & M. Peragallo 1900 were compared. Colony formatio n by overlap of cell ends; weakly silicified, shallow, and flattened v alves; an extremely eccentric raphe, not elevated above the general le vel of the valve; lack of conopea; and striated girdle bands character ize Pseudonitzschia as a natural group and a genus separate from Nitzs chia.