Tratamento taxonômico de Alismataceae do Pantanal brasileiro

Abstract

The Pantanal is one of the largest tropical wetland areas in the world, covering approximately 160,000 km² and located in the Upper Paraguay Basin. In Brazil, the Pantanal floodplain extends over approximately 138,000 km², distributed between the states of Mato Grosso (35%) and Mato Grosso do Sul (65%). Alismataceae is a family of aquatic plants belonging to the order Alismatales. The family comprises 17 genera and 113 species, with a subcosmopolitan distribution. In Brazil, five genera and 40 species occur. Although taxonomic studies on Alismataceae are frequent in semi-arid regions of Brazil, they remain scarce for large wetland areas such as the Pantanal. This study aims to conduct the first taxonomic treatment of Alismataceae in the Brazilian Pantanal. The research was carried out in two main stages. The first stage involved field collections, while the second stage consisted of analyzing botanical material of Alismataceae deposited in the COR, CEN, CPAP, DDMS, ICN, and UFMT herbaria through visits, loans, or exchanges. Additionally, images of specimens from the BHCB, HPAN, MBM, NY, R, RB, UB, UEC, UPCB, and US herbaria were examined through the virtual herbaria Reflora and SpeciesLink, as well as JABOT. At the beginning of the dissertation related work, significant inconsistencies were observed in the data on the diversity of Alismataceae in the Brazilian Pantanal, as recorded in the Flora e Funga do Brasil (FBB) and SpeciesLink. While FBB indicated the occurrence of 16 species, SpeciesLink listed at least 36 names attributed to the family. Through extensive analysis of material deposited in the most representative collections of the family in the Brazilian Pantanal (i.e., CGMS and CPAP herbaria), the occurrence of 19 species was confirmed, distributed among the genera Echinodorus (9 spp.), Sagittaria (4 spp.), Hydrocleys (2 spp.), Helanthium (2 spp.), and Limnocharis (2 spp.), with Sagittaria planitiana being a new record for the state of Mato Grosso. Furthermore, most synonymized names were updated, and some identifications were clarified. For years, the literature indicated the occurrence of Echinodorus cylindricus, E. grandiflorus, E. macrophyllus, and E. lanceolatus in the Pantanal. However, based on the analysis of revised collections and field observations, it was found that specimens previously identified as E. cylindricus correspond to E. glaucus, E. grandiflorus was corrected to E. longiscapus, E. macrophyllus to E. scaber, and E. lanceolatus to E. paniculatus. The results of this study contribute to a better understanding of the diversity of Alismataceae in the Brazilian Pantanal. The taxonomic treatment includes identification keys, detailed morphological descriptions, diagnostic and comparative comments among similar taxa, as well as illustrative plates and species distribution maps within the study area.