This study examined the evolutionary history and diversity of marine gregarine parasites of pelagic zooplankton, and highlighted a unique example of a host-jumping event of cephaloidophorid gregarines between two distantly related host groups, crustaceans and chordates. Candacia bipinnata Giesbrecht, 1889, a free-living calanoid copepod, and a salp, Salpa fusiformis Cuvier, 1804, were collected on oceanic research cruises in 2018 and 2019, in the West Pacific aboard TRV SEISUI MARU and TOYOSHIO MARU, respectively. A molecular phylogeny based on 18S rDNA nested the gregarine parasite from S. fusiformis among cephaloidophorids, within a clade exclusively comprised of gregarines from crustaceans. The relationship between these groups was underpinned with ultrastructural data including the presence of a septum, and similarities in the apices of the epicytic folds. Subsequently, it was concluded to establish a new combination, Cephaloidophora cf. flava n. comb (Ex. Thalicola flava) and transfer the other two members of the Thalicola (also parasites of salps) to the Cephaloidophora. This study also attempted to ascertain the origin of cephaloidophorids in S. fusiformis. However, the relationship between Cephaloidophora bipinnatae n. sp., and C. cf. flava n. comb. had only modest support.

这项研究检查了远洋浮游动物的海洋长尾藻寄生虫的进化历史和多样性，并强调了在两个远亲的寄主群体甲壳类动物和脊索动物之间发生头孢类长尾藻宿主跳跃事件的独特例子。Candacia bipinnata Giesbrecht，1889 年，一种自由生活的calanoid 桡足类动物和一种鲑鱼，Salpa fusiformis Cuvier，1804 年，分别于 2018 年和 2019 年在西太平洋的 TRV SEISUI MARU 和 TOYOSHIO MARU 号的海洋研究巡航中被收集到。基于 18S rDNA 的分子系统发育嵌套了来自梭状芽孢杆菌的 gregarine 寄生虫在头孢类动物中，在一个完全由甲壳类动物群落组成的进化枝中。这些组之间的关系以超微结构数据为基础，包括隔膜的存在，以及上皮皱襞顶端的相似性。随后，得出结论建立一个新的组合，Cephaloidophora cf。弗拉瓦n. 梳理（例如Thalicola flava ）并将Thalicola的另外两个成员（也是鲑鱼的寄生虫）转移到Cephaloidophora。本研究还试图确定梭形梭菌中头孢类动物的起源。然而， Cephaloidophora bipinnatae n.之间的关系。sp. 和C. 参看。弗拉瓦n. 梳子。只得到了适度的支持。