Thecal morphology of selected species of Dinophysis (Dinoflagellata) from the Gulf of Mexico and related hydrography.

Detailed descriptions of the thecal plates of ten species of the genus Dinophysis, one of which is new, are given. Disclosure of a small plate, reported for the first time, necessitates a new plate formula and raises question as to the consistency of the number of plates throughout the Dinophysidae. Hydrology of the sample area is discussed and comments are made relative to the distribution of the species found in the Gulf of Mexico.