Molecular phylogenetic analysis resolves <i>Trisetum</i> (Poaceae: Pooideae: Koeleriinae) polyphyletic: Evidence for a new genus, <i>Sibirotrisetum</i> and resurrection of <i>Acrospelion</i>

Abstract

Abstract To investigate the evolutionary relationships among the species of Trisetum and other members of subtribe Koeleriinae, a phylogeny based on DNA sequences from four gene regions (ITS, rpl32‐trnL spacer, rps16‐trnK spacer, and rps16 intron) is presented. The analyses, including type species of all genera in Koeleriinae ( Acrospelion, Avellinia, Cinnagrostis, Gaudinia, Koeleria, Leptophyllochloa, Limnodea, Peyritschia, Rostraria, Sphenopholis, Trisetaria, Trisetopsis, Trisetum ), along with three outgroups, confirm previous indications of extensive polyphyly of Trisetum. We focus on the monophyletic Trisetum sect. Sibirica clade that we interpret here as a distinct genus, Sibirotrisetum gen. nov. We include a description of Sibirotrisetum with the following seven new combinations: Sibirotrisetum aeneum, S. bifidum, S. henryi, S. scitulum, S. sibiricum, S. sibiricum subsp. litorale , and S. turcicum ; and a single new combination in Acrospelion : A. distichophyllum . Trisetum s.s. is limited to one, two or three species, pending further study.