Department of Botany, National Museum of Nature and Science, Tsukuba 305-0005, Japan.
Sorbonne University, CNRS, UMR7144, Adaptation and Diversity in Marine Environment (AD2M) laboratory, Ecology of Marine Plankton team, Station Biologique de Roscoff, Place Georges Teissier, 29680, Roscoff, France.
Protist. 2020 Feb;171(1):125712. doi: 10.1016/j.protis.2019.125712. Epub 2020 Jan 7.
Entactinaria, an order of Radiolaria, are defined by a specific skeletal structure called "initial spicular system (ISS)". The oldest entactinarians appeared in the Ordovician period, and the extant species are thought to have survived until today. However, the morphological observation revealed that the ISSs of entactinarian families are highly variable, and the validity of this characteristic is questionable. This is supported by the results of 18S and 28S rRNA molecular phylogenetic analysis that suggested the polyphyly of the four families analyzed in this study. Orosphaeridae, Rhizosphaeridae, Hexalonchidae and Hexastylidae should be excluded from the order Entactinaria. Considering the present results and the diversity in the ISS, it is also possible that "living entactinarians" are polyphyletic.
胶磷矿目放射虫，由一种特定的骨骼结构定义，称为“初始刺丝系统（ISS）”。最古老的胶磷矿目放射虫出现在奥陶纪时期，现存的物种被认为一直存活到今天。然而，形态学观察表明，胶磷矿目放射虫科的 ISS 高度可变，并且这种特征的有效性值得怀疑。这一点得到了 18S 和 28S rRNA 分子系统发育分析的结果的支持，该分析表明，本研究分析的四个科是多系的。Orosphaeridae、Rhizosphaeridae、Hexalonchidae 和 Hexastylidae 应从胶磷矿目放射虫目中排除。考虑到目前的结果和 ISS 的多样性，“活的胶磷矿目放射虫”也可能是多系的。
