Rhynchospora is one of the most species-rich genera of Cyperaceae, comprising c. 400 species in 28 sections. Rhyncospora section Tenues is one of the largest sections and one of the most problematic. Because it is morphologically similar to sections Laevinuces, Luzuliformes and Spermodontes, the characters traditionally used to distinguish section Tenues cannot be reliably used to place species into one of these four sections. These four sections are included in the Psilocarya group of Rhynchospora subgenus Rhynchospora with sections Psilocarya and Dichromena. Previous molecular studies of Rhynchospora indicate that species of the Psilocarya group form a clade and are sister to at least some species of the sections being studied here. Since only 11 of the estimated 41 species in these four sections were included in earlier phylogenetic studies, the relationships among these sections remain unclear. To elucidate these relationships, we conducted a molecular phylogenetic analysis for Rhynchospora, based on plastid trnL-F and nuclear ETS and ITS markers, emphasizing species in these four sections. Results show that sections Laevinuces, Spermodontes and Tenues are individually not monophyletic but, grouped together, form a well-supported clade, Rhynchospora section Tenues s.l. Rhynchospora section Luzuliformes is monophyletic but is not a sister clade of section Tenues.

中文翻译：

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重新定义 Rhynchospora section Tenues（莎草科），一种系统发育方法

Rhynchospora是莎草科物种最丰富的属之一，包括c。28个部分400种。Rhyncospora section Tenues 是最大的部分之一，也是最成问题的部分之一。因为它在形态上与 Laevinuces、Luzuliformes 和 Spermodontes 部分相似，传统上用于区分 Tenues 部分的字符不能可靠地用于将物种置于这四个部分之一。这四个部分被包括在 Rhynchospora 亚属 Rhynchospora 的 Psilocarya 组中，其中包括 Psilocarya 和 Dichromena 部分。以前对 Rhynchospora 的分子研究表明，Psilocarya 组的物种形成一个进化枝，并且至少是这里研究的部分物种的姐妹。由于这四个部分中估计的 41 个物种中只有 11 个被包括在早期的系统发育研究中，这些部分之间的关​​系仍不清楚。为了阐明这些关系，我们基于质体 trnL-F 和核 ETS 和 ITS 标记对 Rhynchospora 进行了分子系统发育分析，在这四个部分中强调了物种。结果表明，Laevinuces、Spermodontes 和 Tenues 部分单独不是单系的，但组合在一起形成了一个支持良好的进化枝，Rhynchospora section Tenues sl Rhynchospora section Luzuliformes 是单系的，但不是 Tenues 部分的姐妹进化枝。