Karenia longicanalis sp nov.. (Dinophyceae): a new bloom-forming species isolated from Hong Kong, May 1998

A new dinoflagellate species; Karenia longicanalis sp. nov. is described from a bloom, which occurred in mid-May, 1998 in Victoria Harbour, Hong Kong and the southwestern coastal waters of Hong Kong Island. Live cells have up to 30 yellow-green, round chloroplasts, each containing a pyrenoid, and a spherical centrally located nucleus surrounded by a 'nuclear capsule'. The cell is slightly dorso-ventrally flattened, 17.5-35.0 mum long and 13.75-32.5 mum wide. The epicone and hypocone are hemispherical. The cingulum is displaced about 22% of the body length. A straight apical groove is located to the right of the sulcal axis and extends over the apex and 2/3 down the dorsal side of the epicone. The sulcus extends from the cingulum to the antapex, where it makes an antapical indentation or concavity. No fish kills were observed during this bloom. Karenia longicanalis sp. nov. closely resembles morphologically Karenia digitata and Gymnodinium mikimotoi, and thus belongs to the 'mikimotoi-complex'.