Monophyly and infrageneric variation of Corispermum L. (Chenopodiaceae), evidence from sequence data psbB-psbH, rbcL and ITS

Corispermum is one of the most problematic taxonomic genera in Chenopodiaceae. To understand the phylogeny and infrageneric variation of Corispermum, we sequenced the nuclear ribosomal ITS region and two chloroplast DNA regions (rbcL and psbB-psbH) of 22 species and three varieties of Corispermum and the related genus Agriophyllum. Several representative species of Salsola, Suaeda, Chenopodium, Kalidium and Camphorosma served as outgroups. Our phylogenetic trees confirm that the tribe Corispermeae is monophyletic, Corispermum and Agriophyllum have a close relationship. Corispermum is demonstrated to be monophyletic, and contains at least four clades which, consequently, are served as the foundation of the infrageneric sectional variation of Corispermum, in terms of a combination of molecular data and morphological characters. The evolution of morphological characters for fruit wing and apex, two important characters in generic classification, is consistent with the sectional division of Corispermum, especially to the East Asian and Chinese taxa.