We conducted phylogenetic analyses of molecular data (ITS, trnH-psbA, trnC-trnL, and trnK-rps16) for 71 species of stipoid grasses. Of these species, 30 are native to South America, seven are native to Mexico and/or the southwestern United States, 15 to other parts of North America, 12 to Eurasia and/or the Mediterranean region, and seven to Australia. The outgroup was Glyceria declinata, a member of the Meliceae, a tribe that is in the same clade as and possibly sister to, the Stipeae. The purpose of the study was to evaluate alternative generic treatments of the South American Stipeae, all of which are based on morphological and anatomical information. Questions of particular interest were the merits of recognizing Amelichloa and of including Stipa subgg. Pappostipa and Ptilostipa in Jarava. Trees obtained from separate analyses of the ITS and cpDNA data were poorly resolved. The majority rule consensus tree obtained from the combined data provided strong support for the monophyly of only two currently recognized genera, Piptochaetium and Hesperostipa. There was strong support for a lineage comprising Amelichloa, Jarava s. str., most North American species of Achnatherum, and most samples of Nassella. Amelichloa was included within a poorly resolved Nassella clade that was sister to the Jarava clade. Austrostipa, with the exception of one sample, was monophyletic and sister to the poorly supported Achnatherum-Amelichloa-Nassella-Jarava clade. Stipa subg. Pappostipa formed a separate strongly supported clade if the North American samples of S. speciosa were excluded from consideration. None of the trees support including S. subg. Pappostipa in Jarava. For S. subg. Ptilostipa we obtained no ITS data and cpDNA data for only one species. The cpDNA data placed the species in a clade with two Nassella species

Internal transcribed spacer (ITS) sequences have been determined for a wide range of stipoid grasses (Poaceae, Pooideae, Stipeae). Nardus was confirmed as the most appropriate outgroup. Anisopogon is consistently included among the stipoid genera. Lithachne and Oryza form a clade and are clearly not close to Stipeae, and there is no support for including Brachyelytrum within Stipeae. Ampelodesmos and Diarrhena do appear among the core taxa in some analyses, but their positions are unstable and the evidence for retaining them is limited. So far there is inadequate support for rejecting them from Stipeae, so they should be included in any comprehensive study of the tribe. The ITS phylogeny supports a narrow interpretation of Jarava, one that includes only species with clear adaptations to anemophilous diaspore dispersal. There is no support for Achnatherum s.l. being a monophyletic group, nor are there any clear and consistent groups within it. Nassella, Hesperostipa, and Piptochaetium remain well supported. The data support some internal groupings within Nassella, but the sample size is small. It may be worthwhile investigating subgeneric relationships within Nassella. Anemanthele always appears associated with, and sometimes within, Austrostipa, but its position is inconsistent. We recommend continuing to recognize it at the generic level because of its distinctive morphological characters. Stipa s.s. shows some cohesion, but the results also suggest that some species currently included in the genus do not belong in it, suggestions that are supported by other studies. There has been no advance in understanding Piptatherum. The data support some of the subgeneric groupings within Austrostipa, but suggest that others should be combined. Austrostipa subgen. Falcateae is well supported, in part by a shared deletion. Additional species of Stipa s.s. and Piptatherum are being sequenced to broaden the sampling of these two genera.

The Barro Negro site (23"s lat., 65'37'W long.) in the Altiplano (Puna) of northwestern Argentina contains a well stratified sequence of remains of Hippidwn, the American extinct horse, camelids, and archaeological materials, which is the focus of this study. In addition to establishing a reliable chronology, paleoenvironmental information was obtained based on analyses of pollen and stable isotopes (oxygen and carbon) from bone and marl. The data indicate that Hippidion was present at the site between 12,000 and 10,000 yr B.P., at a time when Altoandean grasslands had expanded to lower elevations. By 10,000 yr B.P., when modern semi-arid sub-puna scrub had replaced the Altoandean grasslands, only camelids (Lama or Vicugnu) were present, simultaneous with the first evidence of local human occupation. This suggests that a climatic shift from cool and moist (winter rain regime) to warm and dry (summer rain regime) conditions took place simultaneously with the disappearance of the American horse and the appearance of camelids and man.

Cataogo de tips depositados en el herbario del Museo hgentino de Cieneias Naturales 46Bemardino RivadaviaP9 (Ba). 11.

No abstract