Abstract:In order to clarify the species diversity of toxic diatom genus Pseudo-nitzschia in domestic coastal, and confirm the ability of domoic acid production from Chinese Pseudo-nitzschia strains, single cells or single chains of Pseudo-nitzschia species were isolated and purified using glass micropipette under invert microscope, and finally the monoclone culture strains of Pseudo-nitzschia species were established and maintained in the laboratory. The morphological characteristics and ultrastructure of colony were observed under light microscope and electron transmission microscope. The molecular phylogenetic tree was constructed based on sequences of internal transcribed spacer (ITS1-5.8S-ITS2). The results showed that two new records of Pseudo-nitzschia from China were identified, i.e., P. galaxiae Lundholm & Moestrup and P. micropora Priisholm, Moestrup & Lundholm. Their detailed morphological characteristics have been described and compared with similar species. All strains of these two new records had no domoic acid (DA) production by using high performance liquid chromatography (HPLC). These would provide basic data for studying species diversity and domoic acid production of genus Pseudo-nitzschia in the China sea.