Phylogenetic relationships of Piptochaetium Presl (Poaceae: Stipeae) and related genera reconstructed from nuclear and chloroplast sequence datasets.

BARBER, L. C.; HAMES, K.; CIALDELLA, A. M.; GIUSSANI L. M.; MORRONE, O.

TAXON

Año: 2008

0040-0262

Piptochaetium (Poaceae, Pooideae, Stipeae) is a New World genus of grasses distributed primarily in temperate South America, with several species extending into Central and southern North America.  The genus comprises 36 species and 2 varieties.  Morphological synapomorphies include the presence of a longitudinally-grooved palea that is longer than the lemma and protrudes from the lemma apex, and lemma margins that are involute and fitted into the palea groove.  The closely related genera Nassella (116 species) and Jarava  (59 species) are also primarily South American, with a few species found in Central and North America.  Published molecular studies to date have focused upon generic-level relationships within the tribe Stipeae, but none have included more than a few representatives of each genus.  We present here results of phylogenetic analyses of these genera based upon combined DNA sequences of both nuclear (ITS) and cpDNA (trnL; rpl16) markers.  Piptochaetium is supported as monophyletic in all studies, and Nassella is recovered as monophyletic if Jarava plumosa is included. Infrageneric relationships of Piptochaetium are also compared to a recent morphological phylogeny of the genus.