Phylogeny of broad-leaved and fine-leaved Festuca lineages (Poaceae) based on nuclear ITS sequences

Abstract

This work presents a reconstruction of the phylogenetic relationships between ten lineages of rescues based on the analysis of nuclear rDNA ITS sequences. Thirty two representatives of most native Western Mediterranean subgenera and sections of Festuca s.l. have been included in this survey in order to establish the evolutionary links between known groups of fescues (subg. Schedonorus, subg. Festuca sect. Festuca and sect. Aulaxyper) and other related Festuca groups that have been poorly studied or that are analyzed here for the first time (subg. Drymanthele, subg. Festuca sect. Subbulbosae, sect. Eskia, sect. Pseudatropis, sect. Scariosae, sect. Pseudoscariosa). Phylogenetic analysis identified two different clades, the "broad-leaved" Festuca and the "fine-leaved" Festuca, using Dactylis, Poa, Deschampsia, Secale, and Brachypodium as outgroups. The "broad-leaved" Festuca clade shows the consecutive sister divergence of the groups: i) the Subbulbosae pro parte clade (some Festuca paniculata s.l. taxa); ii) the Hesperochloa clade (Festuca kingii); iii) the "mixed" clade (incl. sect. Subbulbosae p.p., subg. Drymanthele, sect. Scariosae, and sect. Pseudoscariosa); and iv) the Schedonorus/Lolium clade, subdivided into the "Maghrebian" subclade and the "European + Lolium" subclade. The "fine-leaved" Festuca clade is formed by a paraphyletic assemblage of sectional groups, where sects. Eskia and Pseudatropis are basal to sects. Festuca-Aulaxyper + Vulpia. The closer affinities of Lolium to the European Schedonorus and of Vulpia to Festuca sect. Aulaxyper ("Festuca rubra complex"), stated by previous authors, is confirmed in our analysis. A new nomenclatural combination is proposed (Festuca arundinaced Schreb. subsp. arundinacea var. letourneuxiana (St.-Yves) Torrecilla et Catalán comb. nov.).