Species related to Paspalum denticulatum Trin. are studied systematically, including taxa traditionally placed in the informal group Livida of Paspalum L. The analysis demonstrates Livida to be an artificial group, without characters that delimit it from remaining groups within Paspalum; for this reason, its species are treated as ungrouped within subgenus Paspalum. A total of 11 species are herein described, compared, and analyzed. Paspalum hieronymii Hack., P. jujuyense Zuloaga, P. lividum Trin. ex Schltdl., and P. proliferum Arechav. are maintained as synonyms of P. denticulatum. Paspalum tinctum Chase is here reduced to synonymy under P. hartwegianum E. Fourn. and P. arsenei Chase under P. pubiflorum Rupr. ex E. Fourn. Paspalum pisinnum Swallen and P. trinii Swallen are here treated under the synonymy of P. trichophyllum Henrard. Distribution maps, plates of species not previously illustrated, and SEM microphotographs of the upper anthecia are included, as well as a taxonomic key to differentiate the accepted species. © 2010 Missouri Botanical Press.
