分子和形态分析揭示的 Holcoglossum 族中的两个新兰属：Paraholcoglossum 和 Tsiorchis。
Paraholcoglossum and Tsiorchis, two new orchid genera established by molecular and morphological analyses of the Holcoglossum alliance.
机构信息
Shenzhen Key Laboratory for Orchid Conservation and Utilization, The National Orchid Conservation Center of China and The Orchid Conservation and Research Center of Shenzhen, Shenzhen, China.
出版信息
PLoS One. 2011;6(10):e24864. doi: 10.1371/journal.pone.0024864. Epub 2011 Oct 10.
BACKGROUND
Holcoglossum is a small orchid genus of 12 species ranging from SW China to Thailand and NE India. Although molecular and morphological analyses have been performed to establish the phylogenetic relationships within this genus, the interspecific relations and its relations with allied genera, such as Rhynchostylis, Aerides and Vanda, remain unclear.
METHODOLOGY/PRINCIPAL FINDINGS: In addition to morphological analysis, maximum parsimony, maximum likelihood, and Bayesian inference analyses were performed based on fragments of the nuclear ITS and chloroplast trnL-F and matK genes of 31 taxa (15 Holcoglossum, 14 Aeridinae, 2 outgroups) representing all major clades of the Holcoglossum alliance. The results suggest that Holcoglossum is triphyletic, comprising three clades: the Holcoglossum clade, its sister clade, and a distant clade more closely related to Rhynchostylis, Aerides, and Vanda than to the Holcoglossum clade. The Holcoglossum clade is further divided into three subclades; the genetic distances between these three subclades also support this delimitation. The molecular conclusion is consistent with their distinct morphological characters.
CONCLUSIONS
We propose that the latter two clades comprise two new genera, Paraholcoglossum and Tsiorchis, and Holcoglossum clade divides into three sections. In addition, a new section, Holcoglossum sect. Nujiangensia, and a new species, Holcoglossum linearifolium, are proposed. Some new combinations are made, and a new scheme is provided for the classification of all species of Holcoglossum, Paraholcoglossum, and Tsiorchis.
背景
Holcoglossum 是一个有 12 个种的小型兰科属，分布范围从中国西南部到泰国和印度东北部。尽管已经进行了分子和形态学分析来建立这个属内的系统发育关系，但种间关系及其与相关属，如 Rhynchostylis、Aerides 和 Vanda 的关系仍不清楚。
方法/主要发现：除了形态学分析外，还对代表 Holcoglossum 联盟所有主要分支的 31 个分类群（15 个 Holcoglossum、14 个 Aeridinae、2 个外群）的核 ITS 和叶绿体 trnL-F 和 matK 基因片段进行了最大简约法、最大似然法和贝叶斯推断分析。结果表明，Holcoglossum 是三分的，包括三个分支：Holcoglossum 分支、其姊妹分支和一个与 Rhynchostylis、Aerides 和 Vanda 关系更密切的远支，而不是与 Holcoglossum 分支关系更密切。Holcoglossum 分支进一步分为三个亚分支；这三个亚分支之间的遗传距离也支持这种划分。分子结论与它们明显的形态特征一致。
结论
我们建议后两个分支包括两个新属，Paraholcoglossum 和 Tsiorchis，而 Holcoglossum 分支分为三个部分。此外，提出了一个新的部分，Holcoglossum sect. Nujiangensia，以及一个新种，Holcoglossum linearifolium。进行了一些新的组合，并为 Holcoglossum、Paraholcoglossum 和 Tsiorchis 所有种的分类提供了一个新的方案。
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