Laboratório de Protistologia, Departamento de Zoologia, Universidade Federal do Rio de Janeiro, Brazil.
Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Mol Phylogenet Evol. 2018 Sep;126:382-389. doi: 10.1016/j.ympev.2018.04.026. Epub 2018 Apr 19.
The odontostomatids are among the least studied ciliates, possibly due to their small sizes, restriction to anaerobic environments and difficulty in culturing. Consequently, their phylogenetic affinities to other ciliate taxa are still poorly understood. In the present study, we analyzed newly obtained ribosomal gene sequences of the odontostomatids Discomorphella pedroeneasi and Saprodinium dentatum, together with sequences from the literature, including Epalxella antiquorum and a large assemblage of ciliate sequences representing the major recognized classes. The results show that D. pedroeneasi and S. dentatum form a deep-diverging branch related to metopid and clevelandellid armophoreans, corroborating the old literature. However E. antiquorum clustered with the morphologically discrepant plagiopylids, indicating that either the complex odontostomatid body architecture evolved convergently, or the positioning of E. antiquorum as a plagiopylid is artifactual. A new ciliate class, Odontostomatea n. cl., is proposed based on molecular analyses and comparative morphology of odontostomatids with related taxa.
齿口目纤毛虫是研究最少的纤毛虫之一,这可能是由于它们的体型较小、局限于厌氧环境以及培养困难。因此,它们与其他纤毛虫类群的系统发育关系仍知之甚少。本研究分析了新获得的齿口目纤毛虫 Discomorphella pedroeneasi 和 Saprodinium dentatum 的核糖体基因序列,以及文献中的序列,包括 Epalxella antiquorum 和一大组代表主要公认类群的纤毛虫序列。结果表明,D. pedroeneasi 和 S. dentatum 形成了一个与 metopid 和 clevelandellid armophoreans 关系密切的深分歧分支,这与旧文献相符。然而,E. antiquorum 与形态上不同的偏口目纤毛虫聚在一起,这表明要么是齿口目纤毛虫复杂的身体结构是趋同进化的,要么是 E. antiquorum 作为偏口目纤毛虫的定位是人为的。根据分子分析和与相关类群的齿口目纤毛虫的比较形态学,提出了一个新的纤毛虫类群 Odontostomatea n. cl.。