Description of a new freshwater bloom-forming dinoflagellate with a diatom endosymbiont, Peridiniopsis minima sp. nov. (Peridiniales, Dinophyceae) from China
Zhang, Qi; Liu, Guoxiang; Hu, Zhengyu
A new freshwater dinoflagellate, Peridiniopsis minima Zhang, Liu et Hu sp. nov. (Peridiniales, Dinophyceae), from the Jiulongjiang River, Fujian Province, China, is described. The dinoflagellate can form serious brown freshwater blooms in the river. The cell is very small and the plate formula is: Po, x, 3', 1a, 6'', 5c, 4s (?), 5''', 2''''. The dinoflagellate is characterized by the presence of a eukaryotic endosymbiotic alga. The dinoflagellate cell possesses two different types of nuclei: a dinokaryon and a eukaryotic nucleus from the diatom endosymbiont. Our molecular analyses based on SSU, LSU and ITS rDNA sequences revealed that these freshwater diatom-harbouring Peridiniopsis species forms a strongly supported subclade, very distant from Peridiniopsis borgei, which is the type species of Peridiniopsis, and distinctively separated from marine diatom-harbouring dinoflagellates. The phylogenetic analyses based on endosymbiont SSU rDNA sequences indicate that the diatom endosymbionts of Peridiniopsis species are closely related to centric diatoms, such as Discostella and Cyclotella.