Phylogeny of Nassella (Stipeae, Pooideae, Poaceae) Based on Analyses of Chloroplast and Nuclear Ribosomal DNA, and Morphology

CIALDELLA, A.M.; SEDE, S.; ROMASCHENKO, K.; PETERSON, P; SORENG, R. J.; F.O. ZULOAGA; MORRONE, O.

SYSTEMATIC BOTANY

AMER SOC PLANT TAXONOMISTS

Lugar: Laramie; Año: 2014 vol. 39 p. 814 - 828

0363-6445

The genus Nassella, as currently circumscribed, includes nearly 116 Americanspecies. It is characterized by the florets with a strongly convolute lemma, aconspicuous or inconspicuous crown, and a short palea. Based on 53 species ofNassella and 22 outgroup species, we conducted phylogenetic analyses to test itsmonophyly, the relationships among its species and with allied genera, mainly withAmelichloa and Jarava, to re-examine infrageneric taxa of Stipa now considered withinNassella, and to correlate the phylogenetic hypothesis with the geographicaldistribution of the species. Two plastid (trnT-trnL and rpl32-trnL) and two nuclearribosomal (ITS and ETS) markers as well as morphology were used. Our DNA dataalone and combined with morphology showed Nassella to be paraphyletic, withAmelichloa nested in it. Jarava s.s. appeared as sister group or in a polytomy togetherwith Nassella-Amelichloa. Two main clades were recovered: one with species ofNassella distributed in regions of high altitude from Bolivia and NW Argentina toMexico and northern South America; and the second, with the remaining species ofNassella, and those of Amelichloa, concentrated in NW Argentina, southern Bolivia,central Argentina and Patagonia, southern Brazil, Uruguay, Paraguay and NEArgentina. Monophyly of Amelichloa was strongly supported. None of Stipa subgenera,now under Nassella, were recovered as monophyletic. Two trends were observed:species originally included in subg. Pocostipa gathered together in one of the mainclades, while all sampled species of subg. Stemmatostipa and subg. Stephanostipawere included in the other. The close phylogenetic relationship of Nassella andAmelichloa is not consistent with the morphological differences between these genera.