Romaschenko, Konstantin, Peterson, Paul M., Soreng, Robert J., Garcia-Jacas, Nuria, Futorna, Oksana, and Susanna, Alfonso
We conducted a molecular phylogenetic study of the tribe Stipeae using nine plastid DNA sequences (irnK-rnalK, ,naiK, lrnI1-p.shA, trnL-F, rps3, ndhF, rp132-trnL, rpsl6-irnK, rpsl6 intron), the nuclear ITS DNA regions, and micromorphological characters from the lemma surface. Our large original dataset includes 156 accessions representing 139 species of Stipcae representing all genera currently placed in the tribe. The maximum likelihood and Bayesian analyses of DNA sequences provide strong support for the monophyly ofStipeae; including, in phylogenetic order, Macrochloa as remote sister lineage to all other Stipeae, then a primary stepwise divergence of three deep lineages with a saw-like (SL) lemma epidermal pattern (a plesiomorphic state). The next split is between a lineage (SLI) which bifurcates into separate Eurasian and American clades, and a lineage ofthree parts; a small Pails (SL2) dade, as sister to Piptaiheruin s.str. (SL3), and the achnatheroid dade (AC). The AC exhibits a maize-like lemma epidermal pattern throughout. AC consists ofa core dade ofAustral-Eurasian distribution and a "major American dade" of North and South American distribution. The base chromosome number for Stipeae is somewhat ambiguous but based on our survey it seems most likely to be x = Il or 12. Our phylogenetic hypothesis supports the recognition ofthe following genera and groups (listed by region): Eurasia-Achnatheru,n, "Miliacea group", "Neotrinia" (monotypic), Qrthoraphiuin (monotypic), Pails (also I from North America), Piplaiheruin s.str., Psaminoch/oa (monotypic), Piilagrosiis, Siipa, "Ti,nouria group", and Trikerala; Mediterranean-A ~npeIodesnios (monotypic), Ce/tica (monotypic), Macrochloa (monotypic), and "Stipella-lnaequiglumes group"; Australasia -Anetnanthele (monotypic), and Austrosiipa; North America (NA)-"Eriocoma group", Hesperostipa, Oiyzopsis (monotypic), Piptaiheropsi.c, "Pseudoeriocoma group", and "Stillmania" (monotypic); South America-Aciachne, Amelichloa (also NA), Anatherosilpa (s.str.), Jarava (polyphyletic), Lorenzochloa, Na.cse/Ia (also NA), Oriachne, Papposilpa (also NA), and Pipiochaeiium (also NA). Monophyly of Phaenospermateae including Duthieinae is demonstrated, and its inclusion within or treatment as sister to Stipeae is rejected. [ABSTRACT FROM AUTHOR]