Convergent morphology in Alpinieae (Zingiberaceae): recircumscribing Amomum as a monophyletic genus

The tropical ginger genus Amomum (Zingiberaceae) has always posed challenges for classification based on morphological characters. Previous molecular phylogenetic studies showed Amomum to be paraphyletic but limited sampling and absence of the data of the type Amomum subulatum made it impossible to resolve the paraphyly and make nomenclatural changes. Here, Amomum is further investigated in a multi-marker phylogenetic framework using matK and nrITS including multiple accessions of the type, the genus Elettaria and additional accessions of Amomum, Alpinia, Elettariopsis, Geocharis, Geostachys and Hornstedtia. Amomum is shown to consist of nine clades and Alpinia of six. The genera Elettaria, Elettariopsis, Plagiostachys, and species in Hornstedtia are nested within these clades. Morphological studies of species previously subsumed in Amomum support recognition of new genera that correspond to well-delimited clades in the phylogenetic framework presented here. Recircumscription of the paraphyletic genus Amomum facilitates identification and creates nomenclatural stability. Three genera, Conamomum, Meistera and Wurfbainia, are resurrected, and three new genera Epiamomum, Lanxangia and Sundamomum are described, together with a key to the genera and a nomenclatural synopsis placing 384 specific names (incl. all synonyms) into the new generic framework. Of these 129 represent new combinations and 3 are replacement names. Types of Geocharis and Geostachys are designated. Further studies and specific sampling will be needed to resolve other branches of Alpinioideae containing other polyphyletic genera.

热带姜科（Zingiberaceae）豆蔻属（Amomum）长期以来在基于形态性状的分类学研究中面临诸多挑战。此前的分子系统发育研究已表明豆蔻属为并系群，但由于采样范围有限，且缺乏模式种Amomum subulatum的相关数据，导致无法解决其并系问题并开展分类命名上的调整。本研究采用结合叶绿体matK基因（matK）与核核糖体转录间隔区（nrITS）的多标记系统发育分析框架，对豆蔻属展开了更为深入的探究，共纳入该模式种的多个样品、小豆蔻属（Elettaria）的类群，以及豆蔻属、山姜属（Alpinia）、拟小豆蔻属（Elettariopsis）、地姜属（Geocharis）、穗姜属（Geostachys）和霍氏姜属（Hornstedtia）的额外样品。研究结果显示，豆蔻属包含9个演化支，山姜属则包含6个演化支；小豆蔻属、拟小豆蔻属、斜穗姜属（Plagiostachys）以及霍氏姜属的部分类群均嵌套于这些演化支之中。对此前归入豆蔻属的物种所开展的形态学研究证实，可依据本研究构建的系统发育框架中界定清晰的演化支，建立多个新属。对并系群豆蔻属的重新界定，将有助于类群鉴定并提升分类命名的稳定性。本研究复活了Conamomum、Meistera和Wurfbainia三个属，同时建立了Epiamomum、Lanxangia和Sundamomum三个新属，并附上了分属检索表以及将384个物种学名（含所有同物异名）归入新分类框架的命名综录，其中129个为新组合学名，3个为替代学名。研究指定了地姜属和穗姜属的模式标本。后续仍需开展进一步研究并优化采样策略，以解决姜亚科（Alpinioideae）中包含其他多系群类群的其他分支的系统发育问题。