Figure 2. a–h. Protoperidinium vietnamicum sp. nov.: – a (PC), b (Epi), and e (SEM): cell in the ventral view showing the epithecal plates, descending cingulum, and the cingular list is smooth; – c (PC): cell in right lateral view showing the oblique cingulum; – d (Epi) and f (SEM): cell in dorsal view; – g (SEM): a part of the epitheca in ventral view shows theca’s surface with incomplete meshes and two kinds of pore sizes (arrow and arrowhead); – h (Epi): a part of the epitheca in the dorsal view showing the three intercalary plates (asterisk: 1a) and the plate 4”. Scale bar in Figs a-f, and h = 20 µm.