peruvianum is a heterotypic synonym of A. ostenfeldii and this taxon name should be discontinued. Many of the global harmful algal blooms (HABs) are caused by the genus Alexandrium.

A number of species belonging to this genus produce neurotoxic paralytic shellfish poisoning (PSP) toxins (Anderson et al. 2012) that can severely affect human health and marine biota (Wang 2008). PSP toxins account for the majority of harmful events caused by Alexandrium, however other toxin families, such as spirolides, goniodomins, and gymnodimines (Cembella et al. 2000, Hsia et al. 2006, Van Wagoner et al. 2011) have been detected in some species of the genus and may sometimes occur together in one species or Lapatinib concentration strain (Tomas et al. 2012). Alexandrium species are often globally distributed, occurring in a variety of habitats and spanning all geographic zones (Taylor et al. 1995, Lilly et al. 2007, McCauley et al. 2009). The successful colonization and persistence of Alexandrium in diverse environments have been attributed to advantageous ecophysiological adaptations that many members of the genus possess (Anderson

et al. 2012). Within the genus, Balech (1995) classified species that were morphologically distinct, but clearly related, selleck screening library into groups. Molecular trees, showing that the species of the respective groups typically cluster together, generally support such relationships (Scholin et al. 1994, John et al. 2003, Leaw et al. 2005, Orr et al. 2011). However, morphological delineations within the complexes are not always confirmed by molecular

data (Hansen et al. 2003, Lilly et al. 2005, 2007, Penna et al. 2005) suggesting that original taxonomic distinction of the species in the complexes may not reflect evolutionary relationships. One of the groups defined by Balech is the A. ostenfeldii group (Balech 1995), a globally distributed complex Dynein of species known to produce several different potent phycotoxins: PSTs, spirolides, and gymnodimines (Hansen et al. 1992, Cembella et al. 2000, Van Wagoner et al. 2011). Based on their similar morphology, Balech (1995) considered three formally described species, A. ostenfeldii (Paulsen) Balech and Tangen (Paulsen 1904, Balech and Tangen 1985), A. peruvianum (Balech and B.R. Mendiola) Balech and Tangen (Balech and de Mendiola 1977, Balech and Tangen 1985) and Gonyaulax dimorpha Biecheler (Biecheler 1952) to be closely related. All are characterized by large globe shaped cells covered by thin walled thecae that easily collapse. Most importantly, they share a narrow, conspicuously asymmetrical first apical plate exhibiting a definite large ventral pore with varying dimensions. Alexandrium ostenfeldii and A. peruvianum are formally delineated by differences in cell shape and features of the first apical (1′), sulcal anterior (s.a.