A taxonomic re-assessment in the Chinese Bupleurum (Apiaceae):Insights from morphology, nuclear ribosomal internal transcribed spacer, and chloroplast (trnH-psbA, matK) sequences

摘要

As one of the big genera in Apiaceae,Bupleurum L.has received considerable attention from plant taxonomists.Nevertheless,there are still many gaps in our knowledge of this genus,especially of those species endemic to China that have often been excluded from previous studies.In spite of a few recent studies on the phylogeny and classification of the Chinese Bupleurum,the most essential problem of species delimitation still remains unresolved.We re-evaluate the taxonomy of the Chinese Bupleurum using morphological and molecular evidence.Careful observations of living plants growing the field and herbarium specimens were made to understand the morphological variation and to ensure species identification for the molecular analysis.Phylogenetic analyses were carried out on sequence data of nuclear ribosomal intemal transcribed spacer (nrlTS),trnH-psbA,and matK,using parsimony and Bayesian approaches to evaluate species relationships.Analyses of both nrlTS and combined datasets of the three regions revealed the following results:(i) the Chinese Bupleurum species were divided into two major lineages; and (ii) most species were well defined,but some traditional inter- and infraspecific relationships were not supported.Our results,along with the results of previous works support that the Chinese Bupleurum species were derived from two different lineages and should be placed in Neves and Watson’s subgenus Bupleurum.Our detailed taxonomic re-assessment of several Chinese species resulted in new taxonomic recombinations with rank changes for three species:Bupleurum tenerum,B.amplexicaule,and B.franchetii; new combination for one variety,B.smithii var.flaviflorum; and the description of one variety and one species,B.stenophyllum vat.leiocarpum and B.sikangense.