The family Hypsibiidae comprises four subfamilies, among which Itaquasconinae are the most abundant in genera. Although being morphologically diverse and cosmopolitan, itaquasconins are scarcely reported and their taxonomy is entangled. Here, we present a phylogeny based on three DNA markers and morphological clues obtained from a detailed scanning electron microscopy analysis of bucco‐pharyngeal apparatuses of 25 species representing seven genera. Our study revealed that (a) the polyphyletic Adropion consists of at least three evolutionary lineages, with Guidettion gen. nov. being the sister group of all remaining itaquasconins; (b) stylet supports were independently lost in Astatumen and Insulobius gen. nov.; (c) pharyngeal tube annulation can be divided into two general types, simple and complex, and is stable at the genus level, but being homoplasious (similarly to the apophyses for the insertion of stylet muscles and the shape of the claw bases), it is not useful in inferring phyletic relationships within the subfamily; and (d) Astatumen and Platicrista contain numerous similar species, challenging the current taxonomic classification; moreover, (e) three new taxa are proposed to accommodate the newly recognised lineages: Guidettion gen. nov. (the former Adropion prorsirostre group), Insulobius gen. nov. (for a new Malayan species with a mixture of Astatumen and Itaquascon traits), and Raribius gen. nov. (former Itaquascon spp. with an elongated and narrowed pharyngeal tube terminating with a spherical pharynx). The simple type of annulation is synapomorphic to Hypsibiidae, with single reversals to the uniform buccal tube in Parascon (Itaquasconinae) and in Hypsibiinae. The pharyngeal tube evolved convergently several times, and is of different character in classes Heterotardigrada and Eutardigrada.

中文翻译：

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从缓步动物柔性咽管的进化看 Itaquasconinae 的系统发育

Hypsibiidae 科包括四个亚科，其中 Itaquasconinae 是最丰富的属。尽管形态多样且世界性，itaquasconins 的报道很少，它们的分类也很复杂。在这里，我们提出了基于三个 DNA 标记和形态学线索的系统发育，这些线索是从代表 7 个属的 25 个物种的颊咽器的详细扫描电子显微镜分析中获得的。我们的研究表明（a）多系 Adropion 由至少三个进化谱系组成，具有 Guidettion 基因。十一月 是所有剩余 itaquasconins 的姊妹组；（ b ）Astatumen和Insulobius gen中的探针支持独立丢失。十一月；(c) 咽管环化可分为简单型和复杂型两种，在属水平上是稳定的，但由于同质性（类似于用于插入管心针肌肉的骨突和爪基的形状），它在推断亚科内的系统关系时没有用；(d) Astatumen 和 Platicrista 包含许多相似的物种，挑战当前的分类学分类；此外，(e) 提出了三个新的分类群以适应新认可的谱系：Guidettion gen。十一月 （前 Adropion prorsirostre 组），Insulobius gen。十一月 （对于混合了 Astatumen 和 Itaquascon 特征的新马来亚物种）和 Raribius gen。十一月 （前 Itaquascon spp. 具有细长和狭窄的咽管，终止于球形咽）。简单类型的环化与 Hypsibiidae 是突触的，在 Parascon (Itaquasconinae) 和 Hypsibiinae 中具有单一的反转到均匀的颊管。