• Alexandrium Halim, 1960
• Alexandrium acatenella (Whedon & Kofoid) Balech, 1985
• Alexandrium affine (H. Inoue & Y. Fukuyo) Balech, 1995
• Alexandrium andersoni Balech, 1990
• Alexandrium andersonii Balech, 1990
• Alexandrium angustitabulatum F.J.R. Taylor, 1995
• Alexandrium balechii (Steidinger) F.J.R. Taylor, 1979
• Alexandrium camurascutulum MacKenzie & Todd, 2002
• Alexandrium catenella (Whedon & Kofoid) Balech, 1985
• Alexandrium cohorticula (Balech) Balech, 1985
• Alexandrium compressum (Y. Fukuyo, K. Yoshida & H. Inoue) Balech, 1995
• Alexandrium concavum (K.R. Gaarder) E. Balech, 1985
• Alexandrium depressum (Gaarder) Balech & Tangen, 1985
• Alexandrium excavatum (Braarud) Balech & Tangen, 1985 accepted as Alexandrium tamarense (Lebour) E. Balech, 1995
• Alexandrium foedum Balech, 1990
• Alexandrium fraterculus (Balech) Balech, 1985
• Alexandrium fukuyoi E. Balech, 1985 accepted as Alexandrium affine (H. Inoue & Y. Fukuyo) Balech, 1995
• Alexandrium fundyense Balech, 1985
• Alexandrium gaarderae Nguyen-Ngoc & Larsen, 2004
• Alexandrium globosum Nguyen-Ngoc & Larsen, 2004
• Alexandrium hiranoi Kita & Fukuyo, 1988
• Alexandrium ibericum E. Balech, 1985 accepted as Alexandrium minutum Halim, 1960
• Alexandrium insuetum E. Balech, 1985
• Alexandrium kutnerae (E. Balech) E. Balech, 1985
• Alexandrium leei E. Balech, 1985
• Alexandrium lusitanicum E. Balech, 1985
• Alexandrium margalefi E. Balech, 1994
• Alexandrium margalefii E. Balech, 1994
• Alexandrium minutum Halim, 1960
• Alexandrium monilatum (J.F. Howell) Balech, 1995
• Alexandrium ostenfeldii (Paulsen) Balech & Tangen, 1985
• Alexandrium peruvianum (Balech & Mendiola) Balech & Tangen, 1985
• Alexandrium pseudogoniaulax (Biecheler, 1952) Horiguchi, 1983 ex Kita & Fukuyo, 1992 accepted as Alexandrium pseudogonyaulax (Biecheler) Horiguchi ex Kita & Fukuyo, 1992
• Alexandrium pseudogonyaulax (Biecheler) Horiguchi ex Kita & Fukuyo, 1992
• Alexandrium satoanum K. Yuki & Y. Fukuyo, 1992
• Alexandrium tamarense (Lebour) E. Balech, 1995
• Alexandrium tamiyavanichii Balech, 1994
• Alexandrium tamutum M. Montresor, A. Beran & U. John, 2004
• Alexandrium taylori Balech, 1994
• Alexandrium taylorii Balech, 1994
• Alexandrium tropicale E. Balech, 1985