Congruent species delimitation of two controversial gold-thread nanmu tree species based on morphological and restriction site-associated DNA sequencing data

Species delimitation is fundamental to conservation and sustainable use of economically important forest tree species. However, the delimitation of two highly valued gold-thread nanmu species (Phoebe bournei and P. zhennan) has been confusing and debated. To address this problem, we integrated morphology and restriction site-associated DNA sequencing (RADseq) to define their species boundaries. We obtained highly consistent results from both data sets, supporting two distinct lineages corresponding to P. bournei and P. zhennan. In Phoebe bournei, higher order leaf venation is more prominent, petioles are thicker and leaf apex angle is narrower, compared to P. zhennan. Both data sets also showed that putative P. bournei localities from north-eastern Guizhou were P. zhennan. The two species have different distributions and only overlap in the Wuling Mountains. Phoebe bournei occurs mainly in Central Fujian, southern Jiangxi, the Nanling Mountains and the Wuling Mountains, whereas P. zhenn...物种界定是具有经济价值的林木树种保护与可持续利用的核心基础。然而，两种极具应用价值的金丝楠木——Phoebe bournei与P. zhennan——的物种界定问题长期存在争议与认知混淆。为解决这一难题，本研究整合形态学数据与限制性酶切位点相关DNA测序（restriction site-associated DNA sequencing, RADseq）技术，明确了二者的物种边界。本研究从两组独立数据中获得了高度一致的结果，支持分别对应P. bournei与P. zhennan的两个独立演化支。相较于P. zhennan，P. bournei的高阶叶脉更为凸显，叶柄更为粗壮，叶尖夹角更窄。两组数据均显示，原本被鉴定为P. bournei的贵州东北部采样点实际隶属于P. zhennan。两个物种的分布范围存在显著差异，仅在武陵山区存在分布重叠。P. bournei主要分布于福建中部、江西南部、南岭山脉及武陵山区，而P. zhenn...