Boni Song Aou Xueyimu Rong-Ming Tian Jing Cai Wei-Yan Tan Chang-kun Liu Xing-Jin HE Song-Dong Zhou ^*

• Key Laboratory of Biological Resources and Ecological Environment of the Ministry of Education, College of Life Science, Sichuan University, Chengdu, China

The genus Cyclorhiza is endemic to China and belongs to family Apiaceae. It is widely distributed in the Himalaya-Hengduan Mountains (HHM) region. However, its morphology, phylogeny, phylogeography, taxonomy and evolutionary history were not be investigated due to insufficient sampling and lack of population sampling and plastome data. Additionally, we found that Seseli purpureovaginatum was not similar to Seseli members but resembled Cyclorhiza species in morphology, indicating that the taxonomic position of S. purpureovaginatum need to be re-evaluated.Methods: Firstly, we observed the morphology of the genus. Secondly, we newly sequenced four plastomes and conducted comparative analyses. Thirdly, we used the newly sequenced ITS and cpDNA (matK, trnQ-rps16, trnD-trnT) from 27 populations totaling 244 individuals to explore the genetic diversity and structure. Finally, we performed the phylogenetic analyses based on three datasets (plastomes data, ITS sequences and haplotype) and estimated the origin and divergence time of the genus.The morphology of Cyclorhiza plants and S. purpureovaginatum were highly similar and their plastomes in structure and features were conserved. The genus possessed highly genetic diversity and significant lineage geographic structure, which may be associated with the long term evolutionary history, complex terrain and habitat, and its sexual reproduction mode. The genus Cyclorhiza originated at late Eocene (36.03 Ma), which was closely related to the early uplift of QTP and HDM. And the diversification of the genus occurred at late Oligocene (25.43 Ma) that was largely influenced by the colonization of the newly available climate and terrain. The phylogenetic results showed that Cyclorhiza species clustered into a separate clade and S. purpureovaginatum nested within Cyclorhiza. C. waltonii was sister to C. peucedanifolia, and C. puana clustered with S. purpureovaginatum. Thus, based on the morphology, plastome analyses and phylogenetic evidence, S. purpureovaginatum should be transferred to Cyclorhiza. All these evidence further supported the monophy of the genus after including S. purpureovaginatumwas. Finally, we clarified the generic limits of Cyclorhiza and provided a species classification key index for the genus. In conclusion, the study comprehensively investigated the morphology, phylogeography, phylogeny, taxonomy and evolution of the genus Cyclorhiza for the first time.