title: Gymnodinium smaydae n. sp., a new planktonic phototrophic dinoflagellate from the coastal waters of Western Korea: morphology and molecular characterization.
abstract: The marine phototrophic dinoflagellate Gymnodinium smaydae n. sp. is described from cells prepared for light, scanning, and transmission electron microscopy. Also, sequences of the small (SSU) and large subunits (LSU) and the internal transcribed spacer region (ITS1-5.8S-ITS2) of ribosomal DNA were analyzed. This newly isolated dinoflagellate possessed nuclear chambers, nuclear fibrous connective, an apical groove running in a counterclockwise direction around the apex, and a major accessory pigment peridinin, which are four key features for the genus Gymnodinium. The epicone was conical with a round apex, while the hypocone was ellipsoid. Cells growing photosynthetically were 6.3-10.9 μm long and 5.1-10.0 μm wide, and therefore smaller than any other Gymnodinium species so far reported except Gymnodinium nanum. Cells were covered with polygonal amphiesmal vesicles arranged in 11 horizontal rows, and the vesicles were smaller than those of the other Gymnodinium species. This dinoflagellate had a sharp and elongated ventral ridge reaching half way down the hypocone, unlike other Gymnodinium species. Moreover, displacement of the cingulum was 0.4-0.6 × cell length while in other known Gymnodinium species it is less than 0.3 × cell length. In addition, the new species possessed a peduncle, permanent chloroplasts, pyrenoids, trichocysts, pusule systems, and small knobs along the apical furrow, but it lacked an eyespot, nematocysts, and body scales. The sequence of the SSU, ITS1-5.8S-ITS2, and LSU rDNA region differed by 1.5-3.8%, 6.0-17.4%, and 9.1-17.5%, respectively, from those of the most closely related species. The phylogenetic trees demonstrated that the new species belonged to the Gymnodinium clade at the base of a clade consisting of Gymnodinium acidotum, Gymnodinium dorsalisulcum, Gymnodinium eucyaneum, etc. Based on morphological and molecular data, we suggest that the taxon represents a new species, Gymnodinium smaydae n. sp.
authors.affiliation: School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul, 151-747, Korea.
authors.forename: Nam Seon
authors.initials: NS
authors.lastname: Kang
authors.forename: Hae Jin
authors.initials: HJ
authors.lastname: Jeong
authors.forename: Øjvind
authors.initials: Ø
authors.lastname: Moestrup
authors.forename: Sung Yeon
authors.initials: SY
authors.lastname: Lee
authors.forename: An Suk
authors.initials: AS
authors.lastname: Lim
authors.forename: Tae Young
authors.initials: TY
authors.lastname: Jang
authors.forename: Kyung Ha
authors.initials: KH
authors.lastname: Lee
authors.forename: Moo Joon
authors.initials: MJ
authors.lastname: Lee
authors.forename: Se Hyeon
authors.initials: SH
authors.lastname: Jang
authors.forename: Eric
authors.initials: E
authors.lastname: Potvin
authors.forename: Sook Kyung
authors.initials: SK
authors.lastname: Lee
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Noh
mesh_terms: D002338:Carotenoids / Q000032:analysis; D016000:Cluster Analysis; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D004141:Dinoflagellida / Q000145:classification* / Q000166:cytology / Q000235:genetics / Q000302:isolation & purification*; D020459:Genes, rRNA; D008853:Microscopy; D008969:Molecular Sequence Data; D015388:Organelles / Q000648:ultrastructure; D010788:Photosynthesis; D010802:Phylogeny; D016053:RNA, Protozoan / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D056910:Republic of Korea; D012623:Seawater / Q000469:parasitology*; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D016053:RNA, Protozoan; D012335:RNA, Ribosomal; D012337:RNA, Ribosomal, 18S; C065096:RNA, ribosomal, 26S; C016040:peridinin; D002338:Carotenoids
keywords: ITS; large subunit; mixotrophy; peduncle; protist; small subunit; taxonomy