The phylogenetic and taxonomic affinities of lineages currently assigned to the non‐monophyletic ciliate order Loxocephalida Jankowski (1980) within subclass Scuticociliatia Small (1967) remain unresolved. In the current study, we redescribe the morphology of the type species, Loxocephalus luridus Eberhard (1862) based on two Czech populations and include the first scanning and transmission electron microscopy images of the species. We provide the first 18S rRNA gene sequences for L. luridus and consider its phylogenetic position. Our results support the separation of Dexiotricha from Loxocephalus; however, the former genus is recovered as non‐monophyletic. The monophyly of genus Dexiotricha and that of Loxocephalus + Dexiotricha is rejected. Loxocephalus luridus, together with Dexiotricha species, nests within a fully supported clade with Conchophthirus species, long presumed to belong to the Pleuronematida. Haptophrya is recovered as sister to this clade. The monophyly of the Astomatia Schewiakoff (1896) including Haptophrya is rejected. No clear morphologic synapomorphy is identified for the fully supported clade consisting of Haptophrya, Dexiotricha, Loxocephalus, and Conchophthirus.

中文翻译：

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基于捷克群体的 Loxocephalus luridus Eberhard, 1862 的重新描述和分子特征：对 Loxocephalida Jankowski, 1980 的影响

目前归属于非单系纤毛虫目 Loxocephalida Jankowski (1980)、小盾纤毛亚纲 (Scuticociliatia Small) (1967) 内的谱系的系统发育和分类学亲缘关系仍未得到解决。在当前的研究中，我们重新描述了模式种的形态，光头鳅Eberhard（1862）基于两个捷克种群，包括该物种的第一张扫描和透射电子显微镜图像。我们提供第一个 18S rRNA 基因序列光斑 L. luridus并考虑其系统发育位置。我们的结果支持分离右毛虫从鳅头鱼;然而，前一个属被恢复为非单系。属的单系性右毛虫以及Loxocephalus + 右毛虫被拒绝。光头鳅， 和...一起右毛虫物种，在完全支持的进化枝中筑巢瘿霉属长期以来被认为属于侧线虫纲（Pleuronematida）的物种。弓鱼属被恢复为该分支的姐妹。 Astomatia Schewiakoff (1896) 的单系包括弓鱼属被拒绝。对于由以下组成的完全支持的进化枝，没有确定明确的形态学共性弓鱼属,右毛虫,鳅头鱼， 和瘿霉属。