LAS ESPECIES AMERICANAS DEL GÉNERO CENCHRUS S.L. (POACEAE, PANICOIDEAE, PANICEAE)

Recent phylogenetic studies provide evidence that the group of species considered under Pennisetum, Cenchrus, and Odontelytrum have a common origin and, therefore, their unification and transfer to the genus Cenchrus has been proposed. Nevertheless, no taxonomic treatment which includes all species is available up to now. The purpose of this study is to perform a taxonomic revision of the American species of the genus Cenchrus s.l. (excluding the monotypic genus Odontelytrum , native to Africa). An expanded description of the genus and a key to identify the species is given. For each species, detailed descriptions, the current synonyms, geographic distribution, observations, and illustrations are presented. In total, 41 species are recognized (11 endemic and 8 are adventitious and /or naturalized). Lectotypes are here designated for the following taxa: Gymnotrix chilensis, G. mexicana, G. geniculata, Pennisetum villosum var. humile, P. lanuginosum, Cenchrus crinitus, C. mutilatus, C. palmeri, C. setosus,  C. spinifex and, C. muricatus Phil. Four new synonyms ( Gymnotrix distachya, G. rigida var. longiseta, Pennisetum nervosum var. laxiusculum and C. echinatus fo. longispina ) are proposed and one neotype is suggested for Pennisetum latifolium . In addition, the geographical distribution of C. mutilatus expands to Bolivia.