Three species of the genus Heterodinium Kofoid are reported for the first time in Turkish coastal waters, in the northeastern Mediterranean. The identified species are Heterodinium mediocre Kofoid, H. angulatum Kofoid & Michener and H. inaequale Kofoid. The morphological characteristics of these three species are described and information about their distribution is given. | New records for the genus Heterodinium Kofoid (Dinophyceae) from Turkish coastal waters (North Eastern mediterranean)