South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
PLoS One. 2013 Apr 4;8(4):e60371. doi: 10.1371/journal.pone.0060371. Print 2013.
Orchids have numerous species, and their speciation rates are presumed to be exceptionally high, suggesting that orchids are continuously and actively evolving. The wide diversity of orchids has attracted the interest of evolutionary biologists. In this study, a new orchid was discovered on Danxia Mountain in Guangdong, China. However, the phylogenetic clarification of this new orchid requires further molecular, morphological, and phytogeographic analyses.
METHODOLOGY/PRINCIPAL FINDINGS: A new orchid possesses a labellum with a large Y-shaped callus and two sacs at the base, and cylindrical, fleshy seeds, which make it distinct from all known orchid genera. Phylogenetic methods were applied to a matrix of morphological and molecular characters based on the fragments of the nuclear internal transcribed spacer, chloroplast matK, and rbcL genes of Orchidaceae (74 genera) and Calypsoeae (13 genera). The strict consensus Bayesian inference phylogram strongly supports the division of the Calypsoeae alliance (not including Dactylostalix and Ephippianthus) into seven clades with 11 genera. The sequence data of each species and the morphological characters of each genus were combined into a single dataset. The inferred Bayesian phylogram supports the division of the 13 genera of Calypsoeae into four clades with 13 subclades (genera). Based on the results of our phylogenetic analyses, Calypsoeae, under which the new orchid is classified, represents an independent lineage in the Epidendroideae subfamily.
Analyses of the combined datasets using Bayesian methods revealed strong evidence that Calypsoeae is a monophyletic tribe consisting of eight well-supported clades with 13 subclades (genera), which are all in agreement with the phytogeography of Calypsoeae. The Danxia orchid represents an independent lineage under the tribe Calypsoeae of the subfamily Epidendroideae. This lineage should be treated as a new genus, which we have named Danxiaorchis, that is parallel to Yoania. Both genera are placed under the subtribe Yoaniinae.
兰花拥有众多品种，其物种形成率被认为异常高，这表明兰花在持续而积极地进化。兰花的广泛多样性吸引了进化生物学家的兴趣。本研究在中国广东丹霞山发现了一种新兰花。然而，这种新兰花的系统发育澄清需要进一步的分子、形态和植物地理学分析。
方法/主要发现：一种新兰花具有具大 Y 形胼胝体和基部两个囊的唇瓣，以及圆柱形肉质种子，使其与所有已知的兰花属明显不同。基于兰科（74 属）和 Calypsoeae（13 属）的核内转录间隔区、叶绿体 matK 和 rbcL 基因片段的形态和分子特征矩阵，应用了系统发育方法。严格一致的贝叶斯推断系统发育树强烈支持将 Calypsoeae 联盟（不包括 Dactylostalix 和 Ephippianthus）分为七个分支，包含 11 属。每个物种的序列数据和每个属的形态特征都组合成一个数据集。推断的贝叶斯系统发育树支持将 Calypsoeae 的 13 个属分为四个分支，包含 13 个亚分支（属）。基于我们的系统发育分析结果，新兰花所属的 Calypsoeae 代表了 Epidendroideae 亚科中的一个独立谱系。
使用贝叶斯方法对联合数据集的分析提供了强有力的证据，表明 Calypsoeae 是一个单系部落，由 8 个支持良好的分支组成，包含 13 个亚分支（属），这与 Calypsoeae 的植物地理学完全一致。丹霞山兰花代表了 Epidendroideae 亚科 Calypsoeae 部落中的一个独立谱系。该谱系应被视为一个新属，我们将其命名为 Danxiaorchis，与 Yoania 平行。这两个属都被置于 Yoaniinae 亚属之下。
