Data from: Phylogenetic systematics of subtribe Spiranthinae (Orchidaceae: Orchidoideae: Cranichideae) based on nuclear and plastid DNA sequences of a nearly complete generic sample

Subtribe Spiranthinae is the most species-rich lineage of terrestrial Neotropical orchids, encompassing > 500 species and 40 genera. We conducted maximum parsimony and maximum likelihood phylogenetic analyses of DNA sequence data of plastid matK-trnK and trnL-trnF and nuclear ribosomal ITS sequences for 36 genera and 182 species of Spiranthinae plus appropriate outgroups. The results strongly support monophyly of Spiranthinae (minus Discyphus, Discyphinae and Galeottiella, Galeottiellinae) and five major lineages, namely monospecific Cotylolabium (sister to the remaining Spiranthinae) and the Eurystyles, Pelexia, Spiranthes and Stenorrhynchos clades. Eighteen of the 27 genera of Spiranthinae for which more than one species was included in our analyses are monophyletic. Paraphyly of large genera, such as Cyclopogon and Sarcoglottis, resulted from segregation of particular species or groups of species exhibiting minor modifications of structures directly involved in pollination (e.g. nectary, rostellum and viscidium). Conversely, polyphyly has resulted from convergent evolution of floral attributes in distantly related species (e.g. Mesadenus). Some of the morphological characters used traditionally for generic delimitation and in non-molecular cladistic analyses of Spiranthinae are discussed against the evolutionary framework set by our molecular trees, emphasizing putative synapomorphies and problems derived from inappropriate character coding or incorrect homology assessments. Our ancestral area analysis indicates that Spiranthinae originated in eastern South America, with subsequent migrations and secondary radiations in Mesoamerica and North America, plus a derived migration from the latter region to the Old World (Spiranthes).

绶草亚族（Spiranthinae）是新热带区陆生兰科中物种多样性最高的支系，包含逾500个物种与40个属。本研究针对36个属、182种绶草亚族植物及其适宜外类群，对质体matK-trnK、trnL-trnF序列以及核糖体核内转录间隔区（ITS）序列开展了最大简约法与最大似然法系统发育分析。
分析结果强力支持绶草亚族（剔除Discyphus属及其所在的Discyphinae亚族、Galeottiella属及其所在的Galeottiellinae亚族）为单系群，同时识别出5个主要演化支系：单型属Cotylolabium（为绶草亚族其余类群的姊妹群），以及Eurystyles、Pelexia、绶草属（Spiranthes）和Stenorrhynchos演化支。
本研究纳入1种以上样本的27个绶草亚族属中，有18个属被证实为单系群。Cyclopogon属与Sarcoglottis属等大属的并系起源，源于部分物种或类群的特化分化——这些类群的传粉相关结构（如蜜腺、蕊喙和粘盘）存在细微修饰。反之，多系起源则源于远缘类群间花部性状的趋同演化（如Mesadenus属）。
本研究结合分子系统树构建的演化框架，对传统上用于绶草亚族属级界定以及非分子分支分类分析的部分形态性状展开讨论，重点探讨了推定的共有衍征，以及因性状编码不当或同源性判断错误引发的分类问题。
祖先分布区分析结果显示，绶草亚族起源于南美洲东部，随后向中美洲与北美洲迁移并发生次生辐射演化，另有一支从北美洲衍生并扩散至旧世界（即绶草属Spiranthes）。