Systematics of New World Maytenus (Celastraceae) and a new delimitation of the genus

Maytenus species are distributed in the New World from Argentina to the U. S. A. The genus delimitation has been controversial, especially in relation to the inclusion of Gymnosporia. Maytenus has been treated in a broad sense such that it was considered widely distributed in tropics and subtropics worldwide. Even in its current restricted circumscription, the genus remains paraphyletic with Fraunhofera and Plenckia nested within it. We increased taxon sampling relative to previous studies and sampled species representing the greatest morphological diversity from throughout the geographic distribution in order to confidently delimit monophyletic genera. The phylogenywas inferred using nuclear (ITS and 26S rDNA) and plastid (matK and trnL-F) gene regions together with morphological characters. The species currently recognized as Maytenus were resolved in three distinct clades. Delimitation of a single large genus, by including Fraunhofera and Plenckia within Maytenus, would result in a m...美登木属（Maytenus）物种分布于新世界（New World），地理分布范围从阿根廷延伸至美国。该属的界定长期存在争议，尤以涉及裸实属（Gymnosporia）的归属问题时为甚。美登木属曾被广义界定，曾被认为广泛分布于全球热带与亚热带区域。即便在当前受限的属界定范围内，该属仍为并系类群（paraphyletic），Fraunhofera属与Plenckia属嵌套于其中。相较于此前的相关研究，本研究扩大了类群取样范围，从整个地理分布区内采集了代表最大形态多样性的物种，以期可靠地界定单系属（monophyletic genera）。本研究采用核基因（ITS与26S rDNA）及质体基因（matK与trnL-F）区域，并结合形态性状，对系统发育关系进行了推断。当前被认定为美登木属的物种被划分为三个独立的演化支（clades）。若通过将Fraunhofera属与Plenckia属归入美登木属来界定单一大属，则会导致...