Yoo Jiae, Coats D Wayne, Kim Sunju
Major of Oceanography, Division of Earth Environmental System Science, Pukyong National University, Busan, Korea.
Smithsonian Environmental Research Center, Edgewater, Maryland, USA.
J Eukaryot Microbiol. 2023 Mar;70(2):e12953. doi: 10.1111/jeu.12953. Epub 2022 Nov 15.
Syndinean dinoflagellates of the genus Euduboscquella infect marine ciliates and dinoflagellates. Euduboscquella species infecting dinoflagellates are understudied relative to congeners infecting ciliates and their molecular phylogeny remains uncertain. Morphology, development, and rRNA gene sequences of intracellular parasites infecting heterotrophic dinoflagellates from coastal waters of Busan, Republic of Korea in summer to fall of 2019-2021 indicate that Cucumeridinium coeruleum, Gyrodinium cf. ochraceum, and two unidentified species of Gyrodinium were each infected by a different Euduboscquella species. Morphological features including shield structure, shape and color of the mature trophont, and sporogenic process distinguished each of the four parasites from the 10 previously described species of Euduboscquella. Our molecular and phylogenetic analyses showed considerably greater genetic distance of SSU and ITS-LSU rRNA gene regions among Euduboscquella species infecting dinoflagellates than among those infecting ciliates. Rather than clustering as a group with Euduboscquella species infecting ciliates, SSU rRNA sequences of the four novel parasites spread out across the syndinean Group I phylogeny, occurring in two different clades and a new lineage. Placement of our novel parasites in multiple clades that encompass Ichythyodinium chabelardi strongly indicates that the genus Euduboscquella is paraphyletic.
尤杜博斯奎拉属（Euduboscquella）的辛迪内鞭毛虫感染海洋纤毛虫和鞭毛虫。相对于感染纤毛虫的同属物种，感染鞭毛虫的尤杜博斯奎拉物种的研究较少，其分子系统发育仍不确定。2019年至2021年夏秋季节，从韩国釜山沿海水域感染异养鞭毛虫的细胞内寄生虫的形态、发育和rRNA基因序列表明，蓝瓜形藻（Cucumeridinium coeruleum）、赭色陀螺藻（Gyrodinium cf. ochraceum）和两种未鉴定的陀螺藻物种分别被不同的尤杜博斯奎拉物种感染。包括盾结构、成熟滋养体的形状和颜色以及孢子形成过程在内的形态特征将这四种寄生虫与之前描述的10种尤杜博斯奎拉物种区分开来。我们的分子和系统发育分析表明，感染鞭毛虫的尤杜博斯奎拉物种之间的SSU和ITS-LSU rRNA基因区域的遗传距离比感染纤毛虫的物种之间的遗传距离大得多。这四种新型寄生虫的SSU rRNA序列并没有与感染纤毛虫的尤杜博斯奎拉物种聚为一组，而是分散在辛迪内第一组系统发育树中，出现在两个不同的分支和一个新的谱系中。我们的新型寄生虫在包含查氏鱼碘藻（Ichythyodinium chabelardi）的多个分支中的位置强烈表明尤杜博斯奎拉属是并系的。
