A phylogeny of Piptochaetium (Poaceae: Pooideae: Stipeae) and related genera based on a combined analysis, including trnL-F, rpl16 and morphology

CIALDELLA, A. M., L. M. GIUSSANI, L. AAGENSEN, F. O. ZULOAGA Y O. MORRONE

SYSTEMATIC BOTANY

AMER SOC PLANT TAXONOMISTS

Año: 2007 vol. 32 p. 545 - 559

0363-6445

The tribe Stipeae occurs in temperate and warm temperate grasslands of Eurasia, Australia, andAmerica. Although generic circumscription within the tribe has recently undergone significant changes, theAmerican genus Piptochaetium has been clearly defined by morphological and anatomical characters. It includes 36species and 2 varieties, most of them widely distributed in temperate grasslands of South America. Phylogeneticanalyses were conducted in Piptochaetium and allied genera of the Stipeae, in order to test the monophyly of thegenus, re-examine infrageneric taxa, and analyze relationships among species of this genus and allied genera ofStipeae. Two chloroplast molecular markers, trnL-F and rpl16, as well as morphology were used. Topology betweenmorphological and molecular data mainly differs in the relationships of Piptochaetium with Anatherostipa andPiptatherum. Molecular and combined analyses yielded two major clades in the tribe: the x 5 11 Clade withPiptochaetium, Aciachne, Anatherostipa, and Jarava vaginata, and the Aneuploid Clade with Jarava, Nassella, andPiptatherum. Monophyly of Piptochaetium was confirmed by morphological and total evidence (morphology andDNA data) analyses. Monophyly of sect. Podopogon, sect. Piptochaetium and Nassella were only supported by thetotal evidence analysis. Circumscription of Jarava is also discussed