Speciation and diversification of populations based on disjunct distribution of primitive monocotyledons

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This study was carried out from the respects of phylogeny, phytogeography and taxonomy at specific level and at infraspecific level, focusing especially on the Tofieldiaceae that have been considered one of the most morphologically primitive monocots and are disjunctly distributed, growing in rocky alpine places, alpine meadows, rock faces along rivers, etc., and often on calcareous soils.First, using plastid trnK, trnL and trnL-F sequences and nuclear ITS sequences, we conducted a combined analysis to clarify phylogenetic relationships of the species and infraspecific taxa of Tofieldia and Triantha. Among the three clades that constitute Tofieldia and the clade covering Triantha, each clade turned out to consist of one widely distributed boreal species, with several localized southern species, excepting the clade of Tofieldia calyculata that occupies an isolated phylogenetic position. Further, morphology of leaf apex and leaf margin proved to be of great taxonomic value in Tofieldia.Second, in order to reexamine the taxonomic coherence of Tofieldia nuda, which is disjunctly distributed in eight areas of East Asia, we included individuals from all of the eight distribution areas of T. nuda in the molecular as well as morphological analyses, and proved that T. nuda contains three species and two varieties. The first species corresponds to T. nuda sense stricto, being sister to Tofieldia coccinea. The second species corresponds to Tofieldia furusei, to which we change the status from T. nuda var. furusei. This species is sister to the clade of Tofieldia divergens and Tofieldia thibetica. The third species corresponds to Tofieldia yoshiiana, which was often reduced to T. nuda by former taxonomists. Tofieldia yoshiiana is further divided into three varieties, i.e. var. yoshiiana, var. kanwonensis, comb. nov., and var. hyugaensis, var. nov.