Phalacroma circumsutum is a species of Dinophyceae in the family Dinophysiaceae. They are native to Rio Grande Do Sul, Pará, Rio De Janeiro, Bahia, Amapá, Espirito Santo, and Sergipe.
Definition: Living in the fluid medium (water or air) but unable to maintain their position or distribution independently of the movement of the water/air mass (adapted from Lincoln et al., 1998).