Fungi encompass, in addition to classically well‐studied lineages, an ever‐expanding diversity of poorly known lineages that include, among others, zoosporic chytrid‐like parasites. According to recent phylogenetic analysis based on 18S + 28S rRNA concatenated genes two unusual chytrid‐like fungi Amoeboradix gromovi and Sanchytrium tribonematis form a monophyletic group, the family Sanchytriaceae, which represents a new divergent taxon that remains incertae sedis within Fungi. Zoospores of Amoeboradix gromovi contain one of the longest kinetosomes known in eukaryotic cells, which are composed of microtubular singlets or doublets. However, the ultrastructure of S. tribonematis, the type species of the genus had not been yet studied. Here, we provide the results of TEM investigations of zoospores and sporangia from two strains of S. tribonematis. The two strains are endowed with unusual features. Like in A. gromovi, amoeboid zoospores of S. tribonematis contain a long kinetosome composed of microtubular singlets, and the two orthogonal centrioles in their sporangia have nine microtubular singlets with an internal ring. The morphological and ultrastructural features of S. tribonematis are now included in the improved taxonomic diagnosis for this species.

中文翻译：

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Sanchytrium tribonematis (Sanchytriaceae, Fungi incertae sedis) 的超微结构证实其与变形虫的密切关系

除了经典研究的谱系外，真菌还包括不断扩大的鲜为人知的谱系多样性，其中包括游动孢子壶菌样寄生虫。根据最近基于 18S + 28S rRNA 连接基因的系统发育分析，两种不寻常的壶菌样真菌 Amoeboradix Gromovi 和 Sanchytrium tribonematis 形成了一个单系群，Sanchytriaceae 家族，它代表了一个新的不同分类群，在真菌中仍然是 incertae sedis。Amoeboradix Gromovi 的游动孢子含有真核细胞中已知最长的运动体之一，由微管单线态或双线态组成。然而，尚未研究该属的模式种 S. tribonematis 的超微结构。在这里，我们提供了来自 S. tribonematis 的两个菌株的游动孢子和孢子囊的 TEM 研究结果。这两种菌株具有不同寻常的特征。与 A.gromovi 一样，S. tribonematis 的变形虫游动孢子包含一个由微管单线态组成的长运动体，其孢子囊中的两个正交中心粒有九个带内环的微管单线态。S. tribonematis 的形态学和超微结构特征现在包含在该物种的改进分类学诊断中。