Phylogenetic analysis of Jarava (Poaceae, Pooideae, Stipeae) and related genera: testing the value of the awn indumentum in the circumscription of Jarava

Abstract

Jarava, a genus of the tribe Stipeae with 31 American species, is considered polyphyletic. In previous phylogenetic analyses, despite a few species of Jarava were used, they were included in the Major American Clade (MAC) together with species of Achnatherum, Amelichloa and Nassella. The main goal of this study is to test the monophyly of Jarava and to estimate relationships of Jarava species and allied genera. Eighty-nine species of Stipeae (17 species of Jarava) were included in the analyses of trnH-psbA and ITS regions from plastid and nuclear genomes, respectively. Morphological characters were optimized on one of the shortest trees derived from the combined analysis. Jarava splits into different lineages. Jarava ichu, the type species of the genus, and other eight species of Jarava were grouped into subclade B; another four species were associated with Achnatherum in subclade A. Both subclades A and B were included into the MAC. Three species: Jarava neaei, J. psylantha, and J. subplumosa, were grouped with Pappostipa in subclade C. The close relationship between Jarava and Pappostipa appears as a novelty and they should be considered within this genus or recognized as a new genus sister to Pappostipa. The awn indumentum (hair length and position of long hairs, either in part or the entire awn) and the subacute or acute callus are useful to recognize the group (subclade C). Geographical distribution of Jarava from subclade C overlaps completely with that of Pappostipa. The shared geographical distribution is in accordance with major groupings in our phylogenetic topology.