Phylogenetic reappraisal of Allium subgenus Cyathophora (Amaryllidaceae) and related taxa, with a proposal of two new sections

Abstract

The phylogeny of subgenus Cyathophora and representatives of its closely related taxa within Allium were reconstructed based on nrDNA ITS and two plastid fragments (trnL-F and rpl32-trnL). The constructed phylogenies indicated that subgenus Cyathophora was not monophyletic and to be split in three parts positioned in different clusters. Allium kingdonii was unequivocally placed within subgenus Amerallium and formed an immediate sister relationship with New World Amerallium clade, suggesting an unexpected intercontinental disjunct distribution. For another, Allium trifurcatum was firmly nested within subgenus Butomissa next to A. tuberosum and A. ramosum, but it is distinctly different morphologically from the latter by thinly leathery bulb tunics, uniovulate locule and obviously 3-cleft stigma. Based on the geographic features, morphological and molecular evidences, two new sections, Kingdonia X.J.He et D.Q.Huang for A. kingdonii and Trifurcatum X.J.He et D.Q.Huang for A. trifurcatum, were proposed. The remaining three species of subgenus Cyathophora formed a well-defined clade, and the phylogenetic relationships among them recovered were consistent with previous findings. In addition, A. weschniakowii and A. subtilissimum were proven to be a member of subgenera Rhizirideum sensu stricto (s. str.) and Cepa, respectively, rather than subgenera Cepa and Polyprason previously proposed. Section Rhizomatosa represented by A. caespitosum should be subsumed within section Caespitosoprason of subgenus Rhizirideum s. str.