Euglenids are a diverse group of flagellates that inhabit most environments and exhibit many different nutritional modes. The most prominent euglenids are phototrophs, but phagotrophs constitute the majority of phylogenetic diversity of euglenids. They are pivotal to our understanding of euglenid evolution, yet we are only starting to understand relationships amongst phagotrophs, with the backbone of the tree being most elusive. Ploeotids make up most of this backbone diversity—yet despite their morphological similarities, SSU rDNA analyses and multigene analyses show that they are non-monophyletic. As more ploeotid diversity is sampled, known taxa have coalesced into some subgroups (e.g. Alistosa), but the relationships amongst these are not always supported and some taxa remain unsampled for multigene phylogenetics. Here, we used light microscopy and single-cell transcriptomics to characterize five ploeotid euglenids and place them into a multigene phylogenetic framework. Our analyses place Decastava in Alistosa; while Hemiolia branches with Liburna, establishing the novel clade Karavia. We describe Hemiolia limna, a freshwater-dwelling species in an otherwise marine clade. Intriguingly, two undescribed ploeotids are found to occupy pivotal positions in the tree: Chelandium granulatum nov. gen. nov. sp. branches as sister to Olkasia, and Gaulosia striata nov. gen. nov. sp. remains an orphan taxon.

中文翻译：

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新的倍体类群的系统发育学有助于眼虫树的主干

眼虫是一群不同的鞭毛虫，栖息在大多数环境中并表现出许多不同的营养模式。最著名的眼虫是光养生物，但噬菌生物构成了眼虫系统发育多样性的大部分。它们对于我们理解眼虫进化至关重要，但我们才刚刚开始了解吞噬生物之间的关系，树的主干是最难以捉摸的。Ploeotids 构成了这种主干多样性的大部分，尽管它们的形态相似，但 SSU rDNA 分析和多基因分析表明它们不是单系的。随着更多的全生物多样性被采样，已知的类群已合并为一些亚群（例如Alistosa），但这些亚群之间的关系并不总是得到支持，并且一些类群仍未对多基因系统发育进行采样。这里，我们使用光学显微镜和单细胞转录组学来表征五种倍体眼虫，并将它们放入多基因系统发育框架中。我们的分析地点阿利斯托萨的德卡斯塔瓦；而赫米奥利亚则与利布纳分支，建立了小说分支卡拉维亚。我们描述了Hemiolia limna，一种生活在海洋中的淡水物种。有趣的是，我们发现两个未描述的复叶在树中占据着关键位置：Chelandium gratumatum nov. 将军 十一月 sp。分支为Olkasia和Gaulosia striata 11 月的姐妹。将军 十一月 sp。仍然是一个孤儿分类单元。