Morphological observations on Dinophysis species (Dinophyceae) from Mediterranean coastal waters

Morphological aspects of various Dinophysis species (e.g. D. sacculus, D. fortii and D. acuminata) collected from Mediterranean coastal areas (southern Italy) are described. Data on the fluorescence of Dinophysis are given in addition to cell details in scanning electron and light microscopy. Specimens of D. sacculus from Tyrrhenian brackish waters, where this species has been associated with slight DSP - toxicity of mussels, display high variability in cell shape and size, whereas the thecal ornamentation has a regular pattern. Cells of D. sacculus, as well as D. acuminata from the Straits of Messina, autofluoresce bright red and yellow - orange, indicating the possible presence of both chlorophyll and phycobilin pigments. Globular components similar to food vacuoles, were observed inside a few specimens of the D. acuminata complex and in D. rotundata cells, further supporting the respective mixotrophic capability and the heterotrofic behaviour of these dinoflagellates.