With about 350 species, Paspalum is one of the richest genera within the Poaceae. Its species inhabit ecologically diverse areas along the Americas and they are largely responsible for the biodiversity of grassland ecosystems in South America. Despite its size and relevance, no phylogeny of the genus as a whole is currently available and infrageneric relationships remain uncertain. Many Paspalum species consist of sexual-diploid and apomicticpolyploid cytotypes, and several have arisen through hybridization. In this paper we explore the phylogenetic structure of Paspalum using sequence data of four noncoding cpDNA fragments from a wide array of species which were combined with morphological data for a subset of diploid taxa. Our results confirmed the general monophyly of Paspalum if P. inaequivalve is excluded and the small genus Thrasyopsis is included. Only one of the four currently recognized subgenera was monophyletic but nested within the remainder of the genus. Some informal morphological groups were found to be polyphyletic. The placement of known allopolyploid groups is generally congruent with previously stated hypotheses although some species with shared genomic formulae formed paraphyletic arrangements. Other species formed a basal grade including mostly umbrophilous or hygrophilous species. It is hypothesized that the genus may have diversified as a consequence of the expansion of C4 grass-dominated grasslands in South America.

Somatic chromosome numbers of 131 accessions belonging to 55 Paspalum species from subtropical South America have been determined. All species had x = 10 as a basic chromosome number, except P. almum which had x = 6. Six ploidy levels were found among species with tetraploidy as the most frequent condition. New diploid and octoploid counts were reported. For Paspalum lilloi and P. glabrinode (both 2n = 2x = 20), and for P. ellipticum, P. erianthoides, P. ovale and P. remotum (all 2n = 8x = 80) sporophytic chromosome numbers are presented for the first time. Records that differ from previously reported counts are given for the following species: P. paucifolium (2n = 2x = 20), P. ceresia (2n = 6x = 60), P. conjugatum (2n = 6x = 60), P. alcalinum (2n = 6x = 60) and P. aff. arundinellum (2n ? 1 = 5x ? 1 = 51). These chromosome data are discussed in light of ploidy-level variation and implications for breeding systems within and among species.

The present work intends to clarify the phylogenetic relationships among the species of Paspalum L. belonging to the informal groups Notata/Linearia and Dilatata, and to raise some preliminary hypotheses on the phylogeny of the genus as a whole. A combined dataset including morphological and molecular characters was used to analyze 28 species of Paspalum plus some representatives of related genera of the tribe Paniceae. Analyses were performed using both parsimony and maximum likelihood. The monophyly of Paspalum is not supported nor contradicted. The circumscription of informal groups of Paspalum is discussed, as well as the cladistic treatment of allopolyploid taxa, especially those comprising the Dilatata group. The relationships of members of the Dilatata with their putative progenitors is confirmed, but the monophyly of the group as a whole is not. A close relationship between P. dilatatum Poir. and P. lividum Trin. ex Schltdl. is shown. Our analysis is consistent with the monophyly of a group comprising Notata+Linearia, with a monophyletic Notata group nested within it. The delimitation of the core Notata is proposed by including P. conduplicatum Canto-Dorow, Valls and Longhi-Wagner, P. notatum Flüggé, P. minus E. Fourn., P. pumilum Nees and P. subciliatum Chase.

No abstract

Chromosome numbers were counted in 126 new accessions of 50 Paspalum species from Brazil, Argentina, Paraguay and Bolivia. The chromosome numbers 2n=12, 20, 24, 30, 40, 50, 60, 80

A phylogenetic analysis was performed on 67 species of Digitaria belonging to four subgenera and 26 of the 32 sections recognized in Henrard's monograph. The analysis was based on 113 discrete and six continuous morphological characters. In the resulting topologies the genus Digitaria was monophyletic. In spite of the low support for most groupings, several clades were recovered. The subdivision of Digitaria in the four subgenera proposed by Henrard was not supported since the large subgenus Digitaria appears as a paraphyletic assemblage within which the other three subgenera are nested. Nevertheless, the monophyly of some of Henrard's sections was supported. This is the first approach to the phylogeny of Digitaria. Se llevó a cabo un análisis cladístico. Se incluyeron 67 especies de Digitaria pertenecientes a los 4 subgéneros y a 26 de las 32 secciones reconocidas en la monografía de Henrard. El análisis fue basado en 113 caracteres morfológicos discretos y 6 continuos En las topologías resultantes el género Digitaria resultó monofilético. A pesar del bajo soporte de la mayoría de los grupos, fueron recuperados varios clados. Los resultados no fueron consistentes con la subdivisión de Digitaria en 4 subgéneros propuesta por Henrard, ya que el extenso subgénero Digitaria aparece como un agregado parafilético dentro del cual se hallan anidados los otros tres subgéneros. Sin embargo, la monofilia de algunas secciones fue confirmada. El presente estudio constituye el primer análisis filogenético de Digitaria.

No abstract

No abstract