Tropical Asia is one of the centers of species diversity of flowering plants, in particular the coffee family (Rubiaceae). Prismatomerideae (the Psychotrieae alliance, subfamily Rubioideae) are a mostly Southeast Asian tribe encompassing four genera of shrubs and small trees (monospecific Gentingia and Motleyia, Prismatomeris with 16 spp., Rennellia with 4–5 spp.). We conducted molecular phylogenetic analyses of this group based on the nuclear and plastid sequence data from six markers and using Bayesian inference. The main goal was to produce a robust phylogeny of the tribe, which was subsequently used to (1) reassess its monophyly and phylogenetic position within the Psychotrieae alliance; (2) rigorously test the monophyly of Prismatomeris and Rennellia; (3) assess the phylogenetic relationships between the genera; and (4) evaluate the phylogenetic value of the inflorescence type currently used for species recognition in Rennellia. Motleyia was not sequenced due to the lack of material, and therefore its affinity with the other genera was assessed based on morphology. The tribe was supported as monophyletic and resolved as sister to the (Gaertnereae (Mitchelleae‐Morindeae)) clade. The monophyly of Prismatomeris sensu Johansson was strongly supported, but we argue for the merging of the monospecific genus Motleyia into Prismatomeris based on their strong morphological similarities coupled with the paraphyly of Prismatomeris with respect to Motleyia. Rennellia was strongly supported as paraphyletic with respect to Gentingia. We propose the transfer of the monospecific genus Gentingia to Rennellia, also consistent with their strong morphological resemblance. Prismatomerideae were resolved in two major sister lineages, the Prismatomeris and Rennellia clades, corresponding to our broadly delimited Prismatomeris and Rennellia. Three well‐supported and morphologically distinct subclades were identified within Rennellia s.l., of which one was represented by Rennellia subsessilis, with sessile and reduced umbel‐like inflorescences bearing two to four flowers. The other two subclades have compound spike‐like (or sub‐raceme‐like) and raceme‐like inflorescences, an important distinction in species‐group recognition. We conclude that inflorescence type shows a strong phylogenetic signal and is, therefore, a reliable feature for recognizing groups of species in Rennellia. Additional taxonomic characters are, however, needed for teasing apart closely related species with the same inflorescence types. Subsequent to our taxonomic revision, the tribe Prismatomerideae comprises two genera: Prismatomeris and Rennellia. One and two new combinations, respectively, are presented, bringing the total number of species in the tribe to 25, of which 17 are in Prismatomeris and 8 in Rennellia. A new species key to Rennellia s.l. is presented.

中文翻译：

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Prismatomerideae（Rubiaceae）部落的分子系统及其分类学后果，并指出了花序形态对于雷内利亚种属识别的重要性

亚洲热带是开花植物，特别是咖啡科（蔷薇科）的物种多样性的中心之一。Prismatomerideae（Psychotrieae联盟，Rubioideae的亚科）是一个主要属于东南亚的部落，包括四个属的灌木和小乔木（单种Gentingia和Motleyia，Prismatomeris占16个pp。，Rennellia占4-5个pp。）。我们根据来自六个标记的核和质体序列数据并使用贝叶斯推断对这一组分子进行了系统发育分析。主要目标是建立一个强大的部落系统发育史，随后将其用于（1）重新评估其在Psychotrieae联盟中的单系和系统发育地位；（2）严格测试三角瓣花属和Rennellia ; （3）评估属间的系统发育关系；（4）评估目前用于雷纳利亚（Rennellia）物种识别的花序类型的系统发生价值。由于缺乏物质，未对木霉进行测序，因此基于形态学评估了其与其他属的亲和力。该部落被认为是单系的，并作为（Gaertnereae（Mitchelleae-Morindeae））进化枝的姊妹获得解决。的单系三角瓣花属意义上的约翰逊得到大力支持，但我们认为对于单特异性属的合并Motleyia成三角瓣花属根据加上的并系群的强烈形态学相似三角瓣花属相对于Motleyia。Rennellia被强烈支持为Gentingia的狂犬病。我们建议将单种属Gentingia转移到Rennellia，这也与它们强烈的形态相似性相一致。Prismatomerideae在两个主要的姐妹谱系Prismatomeris和Rennellia进化枝中得到解析，对应于我们广泛界定的Prismatomeris和Rennellia。在雷内利亚（Rennellia）内鉴定出三个支撑良好且形态学上不同的小分支sl，其中一个由Rennellia subsessilis代表，具有无柄和减少的伞形花序，具二到四朵花。其他两个子类别具有复合的穗状（或亚纲状）和总状花序的花序，这在种群识别中是重要的区别。我们得出的结论是，花序类型显示出很强的系统发生信号，因此，是识别雷纳利亚属中各种物种的可靠特征。但是，还需要其他分类学特征来区分具有相同花序类型的密切相关的物种。在我们的分类学修订之后，Prismatomerideae部落包含两个属：Prismatomeris和Rennellia。分别提出了一种和两种新的组合，使部落中的物种总数达到25种，其中Prismatomeris中的17种和Rennellia中的8种。介绍了雷氏菌属新物种的一个关键物种。