Gymnoxanthella radiolariae gen. et sp. nov. (Dinophyceae), a dinoflagellate symbiont from solitary polycystine radiolarians
Gymnoxanthella radiolariae gen. et sp. nov. (Dinophyceae), a dinoflagellate symbiont from solitary polycystine radiolarians
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DOI：
10.1111/jpy.12371
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发表时间：
2016-02
影响因子：
2.9
通讯作者：
Tomoko Yuasa;T. Horiguchi;S. Mayama;O. Takahashi
中科院分区：
文献类型：
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作者：
Tomoko Yuasa;T. Horiguchi;S. Mayama;O. Takahashi
共生甲藻Gymnoxanthella radilariae T. Yuasa et T.本文根据光学、扫描和透射电子显微镜以及SSU和LSU rDNA序列的分子系统发育分析，描述了从多胱氨酸放射虫中分离的Horiguchi gen. et sp. nov.。G.放射虫是在培养物中获得的，并且似乎是无甲的。细胞长9.1-11.4 μm，宽5.7-9.4 μm，腹侧观椭圆形至长椭圆形。它们具有逆时针马蹄形的顶沟，具有囊状腔的核膜，带宽度为一个带的带位移，以及核纤维结缔组织;所有这些都是Gymatelinium sensu stricto（Gymatelinium s.s.）的特征。分子系统发育分析也表明G.放射虫属于裸盖伞属Gymnastinium s.s.的分支。然而，在我们的分子系统发育树中，G.放射虫与匙羹藤属的模式种-褐色匙羹藤属（Gymnastiumfuscum）有较远的亲缘关系。基于我们的物种与其他属和种的一致的形态、遗传和生态分歧，我们认为建立一个新的、独立的属和种是合理的。放射虫的多甲藻共生体中，Brandtodinium已取代Zooxanthella而成为一个新属，但Zooxanthella的名称仍然有效。Brandtodinium是Zooxanthella的一个次异名。研究结果表明，至少有两种甲藻共生体，即多甲藻Zooxanthella nutricula和裸甲藻Gymnastinioid G.放射虫中存在放射虫，它们可能是混合的，并报告为“Z.自19世纪以来，
The symbiotic dinoflagellate Gymnoxanthella radiolariae T. Yuasa et T. Horiguchi gen. et sp. nov. isolated from polycystine radiolarians is described herein based on light, scanning and transmission electron microscopy as well as molecular phylogenetic analyses of SSU and LSU rDNA sequences. Motile cells of G. radiolariae were obtained in culture, and appeared to be unarmored. The cells were 9.1–11.4 μm long and 5.7–9.4 μm wide, and oval to elongate oval in the ventral view. They possessed an counterclockwise horseshoe‐shaped apical groove, a nuclear envelope with vesicular chambers, cingulum displacement with one cingulum width, and the nuclear fibrous connective; all of these are characteristics of Gymnodinium sensu stricto (Gymnodinium s.s.). Molecular phylogenetic analyses also indicated that G. radiolariae belongs to the clade of Gymnodinium s.s. However, in our molecular phylogenetic trees, G. radiolariae was distantly related to Gymnodinium fuscum, the type species of Gymnodinium. Based on the consistent morphological, genetic, and ecological divergence of our species with the other genera and species of Gymnodinium s.s., we considered it justified to erect a new, separate genus and species G. radiolariae gen. et sp. nov. As for the peridinioid symbiont of radiolarians, Brandtodinium has been erected as a new genus instead of Zooxanthella, but the name Zooxanthella is still valid. Brandtodinium is a junior synonym of Zooxanthella. Our results suggest that at least two dinoflagellate symbiont species, peridinioid Zooxanthella nutricula and gymnodinioid G. radiolariae, exist in radiolarians, and that they may have been mixed and reported as “Z. nutricula” since the 19th century.