Within the Alexandrium minutum group sensu Balech, there are several defined morphospecies (A. minutum, A. ibericum, A. angustitabulatum, A. lusitancum) that present similar if not identical PSP toxin profiles. These Alexandrium taxa may be synonomous or conspecific but this issue has not been completely resolved. This A. minutum group is widely distributed - members of this group have been reported from the American and European Atlantic coasts to Taiwan, and New Zealand. They also occur along the west coast of Sweden, throughout the Mediterranean, on the Indian west coast and in southern Australia.
Similar to several other Alexandrium species, A. minutum is a causative organism of the neurotoxin syndrome known as paralytic shellfish poisoning (PSP). Unlike the better known A. tamarense species complex, for which sequencing initiatives are underway, toxic A. minutum strains tend to produce a relatively limited spectrum of PSP toxins (primarily or exclusively gonyautoxin derivatives, such as GTX1-GTX4).
In addition to the PSP toxins, some Alexandrium species can produce allelochemicals affecting other protists. These allelochemical interactions, which are not correlated with the strain-specific content of STX derivatives, may have important implications for bloom dynamics. Whether the production of these allelochemicals is stable for a given strain, or whether it changes with physiological parameters, has not yet been investigated.