A taxonomic treatment of Alismataceae (Alismatales) in the Brazilian Pantanal

Abstract

This study provides a taxonomic treatment of Alismataceae species occurring in the Brazilian Pantanal. Field collections were carried out and analysis of sheets housed in the most representative herbaria of Pantanal were consulted. A total of five genera and 19 species were confirmed in the Brazilian Pantanal. Echinodorus was the most representative genus, with nine species, followed by Sagittaria with four. Taxonomic analyses exclude E. cylindricus and E. lanceolatus, which were reassigned as E. glaucus. Echinodorus grandiflorus was identified as E. longiscapus, and specimens previously identified as E. macrophyllus were mostly updated as E. scaber, with a few reassigned as E. floribundus. New records in E. longiscapus, E. grisebachii and S. planitiana were also documented. Additionally, Aquarius is here proposed as a synonym of Echinodorus, as its segregation is considered unjustified. This study also provides the lectotypification of Sagittaria montevidensis, based on study of original material preserved at G and HAL herbaria. The taxonomic treatment includes identification keys, morphological descriptions, diagnostic and comparative notes for morphologically related taxa, discussions on previously reported taxa, photographic plates, illustrations, and species distribution maps.