Phylogenomics reveal <i>Populusgonggaensis</i> as a hybrid between <i>P.lasiocarpa</i> and <i>P.cathayana</i> (Salicaceae)

High levels of intra-specific polymorphism and frequent hybridisation make it difficult to define species and correctly apply their scientific names. <i>Populus</i> L. is a challenging genus with plentiful natural and artificial hybrids. This study is a part of the project 'Flora of Pan-Himalaya' and aims to determine the taxonomic identity of <i>P.gonggaensis</i> N. Chao & J.R. He and to find out whether it is of hybrid origin. Whole-genome sequencing data were obtained from 57 samples. The SNP matrix was developed for phylogenetic reconstruction, ABBA-BABA statistics, PCA and ADMIXTURE analysis. The results indicate that <i>P.gonggaensis</i> is a spontaneous hybrid between <i>P.lasiocarpa</i> and <i>P.cathayana</i>. This study points out the importance of SNP data and comprehensive analyses for discovering the potential interspecific hybridisation and clarifies the usage of the name. In addition, the lectotype of <i>P.gonggaensis</i> was designated.