No abstract

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

Summary Barkworth, M. E. & Torres, M. A.: Distribution and diagnostic characters of Nassella (Poaceae: Stipeae). – Taxon 50: 439–468. 2001. – ISSN 0040‐0262. Nassella sensu lato includes 116 species, making it one of the largest genera in tribe Stipeae. Argentina has the largest number of species, 72, with the greatest concentration being in the northwestern part of the country. Bolivia, Chile, and Uruguay have 26, 27, and 27 species, respectively. Other South American countries in which the genus is present are Brazil (18 species), Colombia (8), Ecuador (9), Paraguay (4), Peru (18), and Venezuela (2). Guatemala has two species, but Costa Rica only one. Mexico has eight native species, five of which also grow in the United States. One additional species grows in both the United States and Canada. Sixty species are known only from one country; one species, N. mexicana, grows in eight countries. Several new distribution records are documented: N. caespitosa, N. elata, N. leptothera and N. punensis for Bolivia, N. pauciciliata and N. spegazzinii for Brazil, N. airoides, N. argentinensis, N. spegazzinii for Paraguay, and N. tucumana (= N. asperifolia) for Peru. Three new combinations are presented: N. burkartii, N. ligularis, and N. quinqueciliata. Two recently transferred species, N. barrancaensis and N. brachychaeta, are excluded from the genus and N. asperifolia, N. bonariensis, and N. amethystina are placed in synonymy. Tables summarising the distribution of Nassella and its morphological variation are presented.

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.