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Cyst‐motile stage relationship and molecular phylogeny of a new freshwater dinoflagellate Gymnodinium plasticum from P lastic L ake, C anada
Author(s) -
Wang Na,
Luo Zhaohe,
Mertens Kenneth N.,
McCarthy Francine M.G.,
Gu Li,
Gu Haifeng
Publication year - 2017
Publication title -
phycological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.438
H-Index - 44
eISSN - 1440-1835
pISSN - 1322-0829
DOI - 10.1111/pre.12190
Subject(s) - biology , gymnodinium , dinoflagellate , polyphyly , dinophyceae , ribosomal dna , internal transcribed spacer , phylogenetics , molecular phylogenetics , monophyly , botany , ribosomal rna , type species , zoology , genus , clade , ecology , genetics , gene , phytoplankton , nutrient
SUMMARY The dinophyceaen genus Gymnodinium was established with the freshwater species G. fuscum as type. According to Thessen et al . (2012), there are 268 species, with the majority marine species. In recently published molecular phylogenies based on ribosomal DNA sequences, Gymnodinium is polyphyletic. Here, a new freshwater Gymnodinium species, G. plasticum , is described from P lastic L ake, O ntario, C anada. Two strains were established by incubating single cysts, and their morphology was examined with light microscopy and scanning electron microscopy. The cyst had a rounded epicyst and hypocyst with a wide cingulum and smooth surface. Vegetative cells were characterized by an elongated nucleus running vertically and a deep sulcal intrusion. The apical structure complex was horseshoe‐shaped and consisted of two pronounced ridges with a deep internal groove, encircling 80% of the apex. Small subunit ribosomal DNA ( SSU r DNA ), large subunit ribosomal DNA ( LSU r DNA ) and internal transcribed spacer ( ITS ) sequences were obtained from cultured strains. Molecular phylogeny based on concatenated SSU , LSU and ITS sequences supports the monophyly of the G ymnodiniales sensu stricto clade but our results suggest that many Gymnodinium species might need reclassification. Gymnodinium plasticum is closest to Dissodinium pseudolunula in our phylogeny but distant from the type species G. fuscum , as are the other gymnodiniacean taxa.