is an armoured, marine, planktonic dinoflagellate. Cells are very distinctive thanks to the presence of two posterior projections. The ventral projection is longer than the dorsal one. The projections are often toothed (i.e. they have small spines on the tip). Like other Dinophysis
species they have a large hypotheca and a small cap like epitheca. Cells are laterally compressed. The left sulcal list (LSL) is large and often reticulated. D. tripos
is a photosynthetic species with chloroplasts (Larsen & Moestrup 1992).