Compared to the knowledge on toxin structure, detection methods, and toxicology, convincing clarification of the etiology of azaspiracid poisoning was seriously lacking behind for quite a long time. Based upon the seasonal and episodic accumulation of azaspiracid (AZA) toxins in suspension-feeding bivalve molluscs a planktonic source has been suspected from the outset. Most species of Azadinium are small and ovoid to elliptical in shape with a hemispherical hyposome. A detailed morphological analysis supplemented by sequence information then described this strain as the new species Azadinium spinosum. Scientific interest and may provide information for understanding toxin production. Furthermore, phylogenetic information may be useful to identify other potential yet unidentified AZA-producing species. Initial studies mainly aimed at investigating the effect of environmental and nutritional factors on growth and toxin production to allow and subsequently improve large-scale AZA production for toxin isolation.