New Entities of Paspalum and a Synopsis of the Dilatata Group

Abstract

New entities in the allopolyploid Dilatata complex of Paspalum are formally described and illustrated. Three sexual tetraploids formerly subsumed under Paspalum dilatatum are recognized as discrete taxonomic entities: P. plurinerve and P. vacarianum are described as new species, and P. dilatatum subsp. flavescens is upgraded to species rank as P. flavescens. Both P. vacarianum and P. plurinerve are distributed in the Brazilian southern Plateau (Planalto Meridional), in the states of Rio Grande do Sul and Santa Catarina, the first one in the eastern region and the second one in the western region including adjacent areas of NE Argentina. Paspalum flavescens is distributed in southeastern Uruguay and the provinces of Buenos Aires and Córdoba (Argentina). The apomictic allohexaploid P. torrense, distributed along the coastal areas of the Brazilian states of Rio Grande do Sul, Santa Catarina, and Paraná, and adjacent regions along the edge of the southern Plateau, also deserves specific status, whereas two further hexaploid biotypes are differentiated from the pentaploid P. dilatatum var. dilatatum and described as Paspalum dilatatum var. chiru and P. dilatatum var. uruguaianense. Paspalum dilatatum var. chiru is restricted to a small area around the locality of Molles Grande, in the department of Paysandú, Uruguay; whereas P. dilatatum var. uruguaianense is distributed in the SW of Rio Grande do Sul, Brazil, and northern Uruguay. The Dilatata group of Paspalum is thus comprised of 8 species and 3 varieties, which are summarized here and for which an identification key is provided.