Aquatic Macrophytes in Southern Amazonia, Brazil: Richness, Endemism, and Comparative Floristics

Abstract

Southern Amazonia harbors a wide diversity of aquatic macrophyte species because of its diverse wetland habitats and location in the Amazon-Cerrado transition zone, which spans the two largest biogeographic domains in South America. We investigated the taxonomic diversity of aquatic macrophytes in the region with a focus on endemism, species richness, and life forms. We present new records of aquatic macrophyte species and compare our results with other Brazilian phytogeographic domains. We found a high number of species of aquatic macrophytes for the southern Amazon region, comparable to extensive inventories in southern, northeastern, and northern regions of Brazil. We recorded 709 species of aquatic macrophytes in 313 genera and 97 families, which includes 90 species endemic to Brazil and five species endemic to the Brazilian Amazonia. The macrophyte species list of southern Amazonia showed < 25% similarity to inventories in Amazonia and Cerrado. This high diversity of aquatic macrophytes in southern Amazonia, with endemic species and others with restricted ranges, emphasizes the need for conserving these wetlands and vegetation types.