Alexandrium tamarense

Alexandrium tamarense is a species of dinoflagellates known to produce saxitoxin, a neurotoxin which causes the human illness clinically known as paralytic shellfish poisoning (PSP). Multiple species of phytoplankton are known to produce saxitoxin, including at least 10 other species from the genus Alexandrium.

Recent molecular work shows that this species belongs to the Alexandrium tamarense complex (Atama complex, including A. tamarense, Alexandrium fundyense, Alexandrium catenella) and that none of the three original morphospecies designations forms monophyletic groups in the present small ribosomal subunit (SSU)–based and previous large ribsosomal subunit (LSU)–based ribosomal RNA phylogenetic trees, i.e. these species designations are invalid. A. tamarense contains polyunsaturated fatty acids, including docosahexaenoic acid.