Morphological and phylogenetic analysis of a Gymnodinium-like species from the Chinese Coast

A Gymnodinium-like species was studied with light microscopy(LM) and scanning electron microscopy(SEM).Also,the internal transcribed spacers(containing 5.8S rDNA) and large ribosomal subunit DNA(D1-D2) sequences were obtained by PCR amplification,and then sequenced to explore the rela-tionships within our isolate,Gymnodinium and other Gymnodinium-like species,including Karenia,Gyrodinium,Karlodinium and Symbiodinium.The LM observation showed that the species was characterized by moving in a levorotatory direction,visible hypocone,epicone and transverse groove,all of which are typical for Gymnodinium.In addition,two flagella could be found under SEM.The phylogenetic analysis revealed that the isolate grouped with Symbiodium,rather than other relevant dinoflagellates.All results showed our isolate belongs to Symbiodium.The strain was isolated from a red tide water sample,denoting that Symbiodium may be causative species for algal bloom.