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

INT ASSOC PLANT TAXONOMY

Año: 2008 vol. 58 p. 375 - 380

0040-0262

Piptochaetium (Poaceae, Pooideae, Stipeae) is a New World genus of grasses distributed primarily in temperateSouth America, with several species extending into Central and southern North America. The genuscomprises 36 species and 2 varieties. Morphological synapomorphies for the genus include involute lemmamargins that fit into the palea groove, a bi-keeled palea longer than the lemma and protruding from the lemmaapex, and fundamental cell sidewalls that are regularly dentate. The closely related genera Nassella (116 species)and Jarava (59 species) are also primarily South American, with a few species found in Central andNorth America. Published molecular studies to date have focused upon generic-level relationships within thetribe Stipeae, but none have included more than a few representatives of each genus. We present here resultsof phylogenetic analyses of these genera based upon combined DNA sequences of both nuclear (ITS) andcpDNA (rpl16, trnL-F) markers. Piptochaetium is supported as monophyletic in all studies, whereas Nassellais recovered as monophyletic only if Jarava plumosa is included. Infrageneric relationships of Piptochaetiumare also compared to a recent morphological phylogeny of the genus.