Contribuições ao conhecimento sobre a família Euphorbiaceae Juss. na flora do Maranhão: estudo no município de Bacabal

Abstract

The Euphorbiaceae family currently encompasses about 6,300 species and is one of the most diverse, with a nearly cosmopolitan distribution, showing broad morphological variation and economic uses. In Brazil, the family is represented by approximately 1,010 species across 69 genera, occurring in all biomes, with the highest numbers in the Cerrado (420) and the Amazon (273). Currently, Maranhão State records 2,788 collected specimens, a number that is less than desirable, and this gap is aggravated in Bacabal, an ecotone between Amazone and Cerrado biomes, with only 31 collections. Thus, the overall objective of this study was to contribute to taxonomic research on the family Euphorbiaceae in Maranhão, using the municipality of Bacabal as a case study. The specific objectives were: (1) to identify the species recorded in the municipality of Bacabal; (2) to describe the species occurring in the area; (3) to comment on the distribution of species from the municipality; (4) to discuss the morphology of the species found in Bacabal; and (5) to develop an identification key for the Euphorbiaceae recorded in Bacabal. The study analyzed materials through visits to the BMA herbarium, the SpeciesLink platform, and field collections between April/2025 and November/2025. Fertile material was collected, photographed, registered, pressed, and dehydrated. Identification was performed by morphological analysis using a stereoscopic microscope, dichotomous keys, and the Flora do Brasil. The results revealed the occurrence of 18 Euphorbiaceae species, distributed across 12 genera. The richest taxa were Euphorbia (five species) and Astraea (two species). The 44 collections described in this work were incorporated into the previously existing ones (31) and now the municipality of Bacabal has a record of 75 collections of the Euphorbiaceae family. Notably, 66.67% of the identified species (12 taxa) constitute new occurrence records for the municipality, including Jatropha gossypiifolia var. staphysagriifolia as a new occurrence also for the state of Maranhão.