Asteraceae do Parque Estadual das Várzeas do Rio Ivinhema, Mato Grosso do Sul, Brasil

Abstract

Ecotonal areas between major phytogeographic domains concentrate high biological diversity and play a fundamental role in maintaining ecological and evolutionary processes. In this context, megadiverse botanical families such as Asteraceae, which comprise approximately 10% of angiosperms, stand out as the second largest family, with about 1,600 genera and more than 25,000 species distributed worldwide. The family is particularly expressive in open grasslands, forest edges, and clearings. This dissertation investigates the diversity and taxonomy of Asteraceae in the Parque Estadual das Várzeas do Rio Ivinhema (PEVRI), Mato Grosso do Sul, Brazil, a protected area located in a transition zone between the Cerrado and Atlantic Forest domains, characterized by floodable and non-floodable environments associated with the fluvial dynamics of the Ivinhema River. The study was developed based on bimonthly field collections carried out between March 2024 and September 2025, through exploratory walks across all phytophysiognomies of the park, complemented by the analysis of herbarium speci mens. Fertile specimens were georeferenced, herborized, and incorporated into the DDMS Herbarium, with duplicates sent to other national collections. The dissertation is organized into two chapters. The first presents the floristic survey of Asteraceae in the PEVRI, including a species list, identification key, and illustrative plates. A total of 54 species distributed among 36 genera and 12 tribes were recognized, with Eupatorieae (17 species/10 genera), Vernonieae (11/6), and Heliantheae (7/6) being the most representative, in addition to 13 new records for the state of Mato Grosso do Sul. The second chapter consists of the taxonomic treatment of Heliantheae, providing morphological descriptions, identification keys, taxonomic comments, and information on distribution, habitat, and phenology. During this treatment, seven taxa were recognized, two of which present uncertain delimitations, including Aspilia aff. squarrosa, which exhibits relevant morphological variation in relation to available descriptions for the species complex, indicating the need for further taxonomic studies. The results highlight the high richness and diversity of Asteraceae in the PEVRI and reinforce the importance of ecotonal areas as reservoirs of plant biodiversity. This study contributes to reducing knowledge gaps regarding the flora of Mato Grosso do Sul and provides a basis for taxonomic and biogeographic research, as well as conservation actions in transition environments between the Cerrado and Atlantic Forest.