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Abstract Detail


Systematics Section

Peterson, Paul M. [1], Romaschenko, Konstantin [2], Johnson, Gabriel [3].

Towards a better phylogeny in the Chloridoideae (Poaceae).

We conducted a molecular phylogenetic study of the subfamily Chloridoideae using six plastid DNA sequences (ndhA intron, ndhF, rps16-trnK, rps16 intron, rps3, and rpl32-trnL). The Chloridoideae includes between 1420−2000 species worldwide in approximately 140 genera. Our large data set includes 260 species (18.3%) representing 99 genera (69%) of the grasses currently placed in the Chloridoideae. The maximum likelihood and Bayesian analysis of these DNA sequences provides strong support for the monophyly of the Chloridoideae; followed by, in order of divergence: a clade with Merxmuellera rangei and M. papposa sister to three species of Centropodia (C. forskalii, C. glauca, and C. mossamedensis); a Triraphideae clade with Neyraudia reynaudia sister to five species of Triraphis; an Eragrostideae clade with the Cotteinae (includes Cottea and Enneapogon) sister to the Uniolinae (includes Entoplocamia, Tetrachne, and Uniola), and sister to these an Eragrostidinae clade of Ectrosia, Harpachne, and Psammagrostis embedded in a polyphyletic Eragrostis; a Zoysieae clade with Urochondra setulosa sister to a Zoysiinae (Zoysia) clade, and sister to these a Sporobolinae clade that includes Spartina, Calamovilfa, Pogoneura, and Crypsis embedded in a polyphyletic Sporobolus; and sister to the Zoysieae a very large Cynodonteae clade that includes 13 monophyletic subtribes. The unequivocal inclusion of Centropodia within the Chloridoideae warrants recognition of a new tribe, the Centropodieae; and a new generic name will be necessary for Merxmuellera rangei and Merxmuellera papposa, all excluded from the Danthonioideae by Linder et al. (in press). All four species of Centropodia exhibit C4 leaf anatomy and have reported chromosome numbers of 2n = 4x = 24 for C. forskalii and 2n = 8x = 48 for C. glauca, whereas Merxmuellera rangei exhibits C3 leaf anatomy and has a chromosome number of 2n = 6x = 36. The predominant base chromosome number found in the four existing chloridoid tribes is x = 10. A biogeographical history of the entire subfamily will be discussed.

Broader Impacts:


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1 - Smithsonian, Department of Botany, National Museum of Natural History, P.O. Box 37012, Washington, DC, 20013, USA
2 - Botanic Institute of Barcelona, Botany, csic-icub, Pg. del Migdia, s.n., Barcelona, 08038, Spain
3 - Smithsonian, Department of Botany and Laboratories of Analytical Biology, Museum Support Center, 4210 Silver Hill Road, Suitland, MD, 20746, USA

Keywords:
classification
Chloridoideae
grasses
phylogeny
plastid DNA
Poaceae
taxonomy
Biogeography.

Presentation Type: Oral Paper:Papers for Sections
Session: 26
Location: 556B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 9:30 AM
Number: 26006
Abstract ID:675


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