New species and new combinations in the South American genus Lessingianthus (Asteraceae: Vernonieae)

Two new species of the South American genus Lessingianthus (Asteraceae: Vernonieae) are described and illustrated. One of these species, Lessingianthus arctatus, bears a resemblance to L. linearis (Spreng.) H.Rob. and L. rosmarinifolius (Less.) H.Rob., but can be separated from them by its almost glabrous phyllaries, solitary heads and longer internodes. The other new taxon, Lessingianthus longicuspis, can be easily separated from L. cataractarum (Hieron.) H.Rob. and L. bardanoides (Less.) H.Rob., and other taxa of the genus, by the combination of petiolate leaves, aristate phyllaries and inflorescence bracts alternate to the heads. Four other taxa previously included in Vernonia are transferred to the genus Lessingianthus. © Trustees of the Royal Botanic Garden Edinburgh 2008.Fil: Dematteis, Massimiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentin