A phylogeny of the Triraphideae including Habrochloa and Nematopoa (Poaceae, Chloridoideae)

Abstract

To investigate the evolutionary relationships among species of the tribe Triraphideae (including two monotypic genera, Habrochloa and Nematopoa), we generated a phylogeny based on DNA sequences from nuclear ribosomal (ITS) and four plastid markers (rps16-trnK, rps16 intron, rpl32-trnL, and ndhA intron). Habrochloa and Nematopoa form a clade that is sister to Neyraudia and Triraphis. Member of the Triraphideae have paniculate inflorescences, 3-veined, marginally ciliate lemmas, usually with hairy lateral veins, that are apically bifid and awned from between a sinus. A description of the Triraphideae and key to the genera is provided, and the biogeography is discussed, likely originating in Africa.

Keywords: Classification; Habrochloa; Nematopoa; Neyraudia; Triraphideae; Triraphis; molecular phylogenetics.

Figure 1.

Maximum-likelihood tree inferred from combined plastid (rps16-trnK, rps16 intron, rpl32-trnL, and ndhA intron) and ITS sequences. Numbers above branches are posterior probabilities; numbers below branches are bootstrap values; thick branches indicate bootstrap ≥ 90% and posterior probabilities of 1.00; DAN = Danthonioideae; tribes within the Chloridoideae = *, include: CEN = Centropodieae, TRI = Triraphideae, ERA = Eragrostideae, ZOY = Zoysieae, and CYN = Cynodonteae. Scale bar: 2%.