biodiversity, Solanales, spiny solanums.

The geographic position of Maranhão in a transitional area between the Amazonia and the Cerrado, with areas influenced by the Caatinga, reflects in the unique floristic composition of native plants. However, the history of fires and deforestation in the state affects biodiversity, requiring strategies for its maintenance. Thus, knowledge of the flora is of utmost importance, especially for botanical genera that are scientifically little explored in the territory of Maranhão. Known as spiny solanums, Leptostemonum is the largest subgenus of Solanum, represents a monophyletic group, and is the most representative group of Solanaceae for Maranhão. Worldwide, the genus contains approximately 580 species, divided into 32 smaller clades and is morphologically delimited by the following combination of characters: aculeate plants with indumentum of stellate trichomes and stamens thin towards the apex. This study proposes a taxonomic treatment for Solanum subgen. Leptostemonum in Maranhão, focusing on its conservation, through an inventory, descriptions, taxonomic key, photographic plates, illustrations, comments on habitat, ecology, phenology and analysis of the conservation status, as well as proposal of actions for the protection of the species. For this, collecting expeditions will be carried out, visits to the herbaria CCAA, CEN, HABIT, HDELTA, HF, IAN, MAR, MG, SLUI and UB, in addition to collecting data available in broad access databases, such as Specieslink, GBIF, Solanaceae Source and Reflora. The herborized material will be deposited in the MAR herbarium, with duplicates sent to the MG and RB herbaria. The descriptions will follow the specialized literature for Solanum. To assign threat categories in order to support a state list of threatened species, we will use IUCN criteria. To date, eight herbaria have been visited and 14 species of Solanum subg. Leptostemonum were recorded for Maranhão. Two sampled species have not yet been identified. The preliminary result includes species from more preserved environments, but also from anthropized environments, in addition to the record of a species endemic to the state that is threatened with extinction.