Morphology, ultrastructure and phylogeny of Takayama xiamenensis sp nov (Gymnodiniales, Dinophyceae) from the East China Sea

A new species, Takayama xiamenensis (Kareniaceae, Dinophyceae), was isolated from Xiamen Harbor, East China Sea, and its morphology was examined using light microscopy, scanning electron microscopy, and transmission electron microscopy (TEM). The vegetative cells of T. xiamenensis were 20.0-27.0 mu m long, 18.0-23.0 mu m wide and 17.0-20.5 mu m thick. The apical groove was deeply sigmoid, and the sulcus extended into the epicone as a distinctive finger-like protrusion. Epifluorescence microscopy revealed a large, cup-shaped nucleus, filling most of the epicone. TEM showed that the chloroplasts were enveloped by two membranes and that some chloroplasts possessed large, bulging pyrenoids. Partial large subunit ribosomal DNA sequences of two strains of T. xiamenensis were identical to the putative T. acrotrocha strains from Italy, suggesting these strains might be conspecific. The original description of T. acrotrocha from Australia does not include a finger-like protrusion, thus justifying the new species description.