Materials and methods
Morphological comparison: Morphological data were recorded from field collections and herbarium specimens. Voucher specimens of our collections were deposited in the herbarium of the Kunming Institute of Botany (KUN), Kunming, China. Herbarium specimens of the S . sect.Irregulares were examined from CDBI, CSFI, GXMG, IBK, IBSC, IMC, KUN, NAS, PE, SM, SYS, SZ and WUK (acronyms followhttps://sweetgum.nybg.org/science/ih/), either by examining the specimens directly or their digital images provided by the National Plant Specimen Resource Center (http://www.cvh.ac.cn/index.php), and JSTOR Global Plants web portal (https://plants.jstor.org/).
Molecular analyses: We sampled 17 collections representing 11 species of Saxifraga sect. Irregulares , including the new species.Saxifraga sinomontana J.T.Pan & Gornall from S. sect. CiliataeHaw. was selected as the outgroup based on previously molecular phylogenetic analyses (Tkach et al. 2015). Leaf materials were collected in the field and from dried herbarium specimens, and sequences for other taxa were obtained from GenBank (Table 1).
Total genomic DNA was extracted from leaf material using DP305 Plant Genomic DNA kits (Tiangen, Beijing, China) following the manufacturer’s protocol. Three chloroplast regions (matK , psba-trnH ,psaJ-rpl33 ) were extracted from the chloroplast genome data performed on GetOrganelle pipeline (Jin et al. 2020). A concatenation-based approach was conducted and aligned in MAFFT 7 (Katoh, Rozewicki and Yamada 2019). Phylogenetic analysis based on maximum likelihood was implemented in IQ-Tree with 1,000 bootstrap (BS) replicates to assess clade support (Nguyen et al. 2015). Bayesian inference tree was generated using MrBayes version 3.2.6 (Huelsenbeck John P. 2001).