A molecular phylogeny and classification of the Cteniinae, Farragininae, Gouiniinae, Gymnopogoninae, Perotidinae, and Trichoneurinae (Poaceae: Chloridoideae: Cynodonteae)

The classification of twenty Cynodonteae genera (Bewsia, Craspedorhachis, Ctenium, Dignathia, Farrago, Goiania, Gymnopogon, Latipes, Leptocarydion, Leptothrium, Lophacme, Lopholepis, Mosdenia, Perotis, Schenckochloa, Toliara, Trichoneura, Trigonochloa, Triplasis, Vaseyochloa) has been poorly understood. The goals of this study were to reconstruct the evolutionary history of the tribe Cynodonteae, emphasizing these twenty genera using molecular data with increased species sampling. A phylogenetic analysis was conducted on 159 samples, of which 94 species (140 individuals) were in the Cynodonteae, using four plastid (rpl32-trnL spacer, ndhA intron, rps16-trnK spacer, rps16 intron) and nuclear ITS 1&2 (ribosomal internal transcribed spacer regions) sequences to infer evolutionary relationships and revise the classification. Strong support was found for six lineages. Craspedorhachis, Ctenium, Dignathia, Gymnopogon, Trichoneura, and Triplasis appear monophyletic; Leptothrium is paraphyletic with Latipes inermis embedded within; Perotis is paraphyletic with Lopholepis and Toliara embedded within; and Goiania is monophyletic with the resurrection of Schenckochloa. The molecular results support the recognition of six subtribes; five (Cteniinae, Farragininae, Gymnopogoninae, Perotidinae, Trichoneurinae) are newly described. A new genus, Tridentopsis, is described; five new combinations, Leptothrium inerme, Perotis arenacea, Perotis ornithocephala, Tridentopsis eragrostoides, and Tridentopsis mutica are made; and Holboellia ornithocephala is lectotypified.