AUTHOR=Liu Rong , Wang Hong , Yang Jun-Bo , Corlett Richard T. , Randle Christopher P. , Li De-Zhu , Yu Wen-Bin 

TITLE=Cryptic Species Diversification of the Pedicularis siphonantha Complex (Orobanchaceae) in the Mountains of Southwest China Since the Pliocene

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.811206

DOI=10.3389/fpls.2022.811206

ISSN=1664-462X

ABSTRACT=<p>Morphological approaches often fail to delimit species in recently derived species complexes. This can be exacerbated in historical collections which may have lost key features in specimen preparation and preservation. Here, we examine the <italic>Pedicularis siphonantha</italic> complex, endemic to the Mountains of Southwest China. This complex is characterized by its red/purple/pink and long-tubular corolla, and twisted, beaked galea. However, herbarium specimens are often difficult to identify to species. Molecular approaches using nrITS or nuclear ribosomal internal transcribed spacer (nrITS) + plastid DNA (ptDNA) have been successfully used for species identification in <italic>Pedicularis</italic>. To resolve taxonomic confusion in the <italic>Pedicularis siphonantha</italic> complex, we reconstructed phylogenies of the complex using nrITS and four plastid DNA loci (<italic>matK</italic>, <italic>rbcL</italic>, <italic>trnH-psbA</italic>, and <italic>trnL-F</italic>). To recover as much of the phylogenetic history as possible, we sampled individuals at the population level. Topological incongruence between the nrITS and ptDNA datasets was recovered in clades including two widely distributed species, <italic>Pedicularis milliana</italic> and <italic>Pedicularis tenuituba</italic>. Based on morphological, geographical, and genetic evidence, we suggest that hybridization/introgression has occurred between <italic>P. milliana</italic> and <italic>Pedicularis sigmoidea</italic>/<italic>Pedicularis</italic> sp. 1 in the Yulong Snow Mountain of Lijiang, northwest Yunnan, and between <italic>P. tenuituba</italic> and <italic>Pedicularis leptosiphon</italic> in Ninglang, northwest Yunnan. After removing conflicting DNA regions in <italic>Pedicularis dolichosiphon</italic> (nrITS) and <italic>P. milliana</italic> (ptDNA), the concatenated nrITS and ptDNA phylogenies distinguish 11 species in the <italic>P. siphonantha</italic> complex, including two undescribed species, from the Jiaozi and Yulong Snow Mountains, respectively. Phylogeographical analyses indicate that the <italic>P. siponantha</italic> complex originated from south of the Hengduan Mountains, expanding north to the Himalayas and the Yunnan-Guizhou Plateau. Moreover, the uplift of the Qinghai-Tibet Plateau and climate oscillations may have driven further diversification in the complex.</p>