Sibling species of mutualistic Symbiodinium clade G from bioeroding sponges in the western Pacific and western Atlantic oceans

Dinoflagellates in the genus Symbiodinium associate with a broad array of metazoan and protistian hosts. Symbiodinium-based symbioses involving bioeroding sponge hosts have received less attention than those involving scleractinian hosts. Certain species of common Cliona harbor high densities of an ecologically restricted group of Symbiodinium, referred to as Clade G. The relationships of these unusual Clade G Symbiodinium with Foraminifera, sponges, and black coral (Antipatharia) are rarely studied. Nonetheless, analyses of genetic evidence indicate that Clade G likely comprises several distinct species. Here we use genetic data in combination with ecological and geographic evidence to formally describe Symbiodinium endoclionum sp. nov. obtained from the Pacific boring sponge Cliona orientalis and S. spongiolum sp. nov. from the congeneric western Atlantic sponge C. varians. These species appear to be part of an adaptive radiation of Clade G lineages specialized to the metazoan phyla P...

虫黄藻属（Symbiodinium，隶属于甲藻门（Dinoflagellates））的物种，可与多种后生动物（metazoan）及原生生物（protistian）宿主形成共生关系。相较于以石珊瑚（scleractinian）为宿主的虫黄藻共生体系，以生物侵蚀海绵为宿主的此类共生关系受关注程度较低。常见的穿贝海绵属（Cliona）的部分物种，体内携带着高密度的一类生态位受限的虫黄藻类群——G支系（Clade G）。这类特殊的G支系虫黄藻与有孔虫（Foraminifera）、海绵及黑珊瑚（Antipatharia）之间的共生关系鲜有研究。尽管如此，遗传证据分析表明，G支系大概率包含多个独立物种。本研究结合遗传数据与生态、地理证据，正式描述了两株新种虫黄藻：从太平洋钻孔海绵东方穿贝海绵（Cliona orientalis）中分离得到的Symbiodinium endoclionum新种（sp. nov.），以及从同属西大西洋海绵变异穿贝海绵（C. varians）中分离得到的S. spongiolum新种。上述类群似乎属于G支系适应性辐射的一部分，该支系特化于后生动物门P……