Durinskia baltica (Dinophyceae), a newly recorded species and genus from China, and its systematics

A freshwater dinoflagellate was identified as Durinskia baltica (Levander) Carty & Cox by morphological characteristics, with the plate formula: Po, x, 4', 2a, 6 '', 5c, 4s, 5''', 2"". Durinskia was a newly recorded dinoflagellate genus for China with two anterior intercalary plates and six characteristic precingular plates. Partial sequences of the small and large subunit ribosomal DNA and internal transcribed spacer sequences for the dinoflagellate cells were obtained from field samples. Molecular phylogenetic results indicated Durinskia species could cluster into a monophyletic group, which were distinct from Peridinium species. According to morphological and molecular evidence, it was agreed that the genus Durinskia was separated from the genus Peridinium, which could be a polyphyletic group. In addition, D. baltica was an infrequent diatom-harboring dinoflagellate which was known to possess an endosymbiotic diatom or diatom-like alga. The phylogenetic analyses indicated that D. baltica had a close affinity with Peridiniopsis penardii and P. niei, common freshwater bloom-forming species in China