Pleurostylia serrulata and two allied new species from Africa are actually members of the new world Crossopetalum (Celastraceae)

Based on phylogenetic analyses using rDNA and plastid sequence data, and the examination of morphological characters, we infer that Pleurostylia, as currently delimited, is a polyphyletic group. Pleurostylia serrulata and two newly described species from Africa are part of the New World Crossopetalum lineage. By contrast, Pleurostylia s. s. consists of all remaining species, which form a clade nested within a primarily Malagasy lineage. We present preliminary evidence that Pleurostylia opposita, the most geographically widespread species in the entire Celastraceae family, may include cryptic species. Although molecular evidence supports the monophyly of Crossopetalum, this genus does not appear to be well defined by a single morphological synapomorphy, rather the following combination of character states is diagnostic: 4-merous flowers; stamens inserted in the sinuses of a ± 4-lobed intrastaminal floral disk; pistil (2- or) 4-locular with one atropous ovule per locule; stigma conspicuou...基于核糖体DNA（rDNA）与质体序列数据的系统发育分析，结合形态特征检视结果，我们推断当前界定的扁枝藤属（Pleurostylia）为复系类群。具锯齿扁枝藤（Pleurostylia serrulata）以及两个产自非洲的新描述物种，隶属于新世界的十字藤属（Crossopetalum）支系。与之相对，狭义扁枝藤属（Pleurostylia s. s.）包含其余所有物种，这些物种构成一个嵌套于以马达加斯加为主的支系内的单系演化枝。我们提供初步证据表明，对生扁枝藤（Pleurostylia opposita）作为整个卫矛科（Celastraceae）地理分布最广的物种，可能包含隐存物种。尽管分子证据支持十字藤属（Crossopetalum）的单系性，但该属似乎无法通过单一形态共源性状进行明确界定，反而需通过以下性状状态组合作为鉴别依据：4基数花；雄蕊着生于近4裂的花内雄蕊盘的弯缺处；雌蕊（2或）4室，每室具1枚直生胚珠；柱头显著……