Recent phylogenetic hypotheses reveal that Thesium (Santalaceae) is paraphyletic with respect to Austroamericium, Chrysothesium, Kunkeliella and Thesidium, suggesting the need for generic realignment. In addition, existing subgeneric and sectional classifications of this large genus lack a phylogenetic basis, thus compromising their predictive value. Using an expanded taxon sampling and a combination of nuclear (ITS) and chloroplast (matK, rpl32‐trnL, trnL‐F) DNA sequence data, we therefore re‐assessed the phylogenetic relationships of Thesium and used these as the basis of a new subgeneric classification of the genus. Our phylogeny confirms the need to sink the four segregate genera to render Thesium monophyletic. In addition, it resolves five well‐supported major clades within Thesium that we recognize as subgenera. Within Thesium, the South African endemic subgenus Hagnothesium is sister to the Eurasian subgenus Thesium (including Kunkeliella and Mauritanica). The subgenus Psilothesium, occurring in tropical South America (formerly genus Austroamericium) and tropical Africa, is sister to the rest of the subgenera, which are all confined to South Africa. Within the latter, the subgenus Discothesium consists of subtropical and temperate species, whereas subgenus Frisea, comprising the previously recognized sections Annulata, Barbata, Frisea, Imberbia and Penicillata, is entirely of the Greater Cape Floristic Region. To facilitate identification of subgenera, we identify morphological ancestral characters and present an identification key, brief diagnoses, species assigned, distribution and ecological data.

中文翻译：

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基于分子系统发育数据的Thesium（Santalaceae）亚种分类

最近的系统发育假说表明，Thesium（Santalaceae）与Austroamericium，Chrysothesium，Kunkeliella和Thesidium具有亲缘关系，这表明需要进行通用重组。此外，该大属的现有亚属和部分分类缺乏系统发育基础，因此损害了它们的预测价值。因此，使用扩展的分类单元采样以及核（ITS）和叶绿体（matK，rpl32-trnL，trnL-F）DNA序列数据的组合，我们重新评估了Thesium的系统发育关系。并以此为基础对属进行新的亚属分类。我们的系统进化论证实，有必要沉没这四个分离的属来使Thesium单系化。此外，它还解决了Thesium内五个得到良好支持的主要进化枝，这些进化枝我们被认为是亚属。在百蕊，南非特有亚属Hagnothesium是姐姐欧亚亚属百蕊（包括Kunkeliella和Mauritanica）。Psilothesium属，发生在南美热带地区（以前为Austroamericium属））和热带非洲，是该亚属其余地区的姊妹，它们都局限于南非。在后者中，迪斯科舞厅属由亚热带和温带种组成，而弗里西亚属包括先前公认的Annulata，Barbata，Frisai，Imberbia和Penicillata区域，完全属于大开普植物区。为了方便鉴定亚属，我们鉴定了形态祖先特征并提出了鉴定关键，简要诊断，物种分配，分布和生态数据。