Data from collections in the Amazon region of Maranhão

Priority areas for conservation are largely defined based on information about biodiversity. However, the available information on species richness is heavily biased due to low sampling density, especially in hard-to-reach areas such as the Amazon region of Brazil. Here, we quantified the efforts to inventory the flora of the Maranhão Amazon, demonstrating the evolution of collection records (herbarium specimens) and recognizing the historical and contemporary figures involved in this process. Thus, we explore the hypothesis that, despite being located in a marginal area of the Amazon, the Amazon region stands out for its uniqueness and richness, but it is under-sampled in terms of research and scientific studies. We retrieved 20,181 collection records from 89 out of 108 municipalities comprising the Maranhão Amazon. The vast majority of collection records (~48%) come from São Luís Island and the municipality of Buriticupu, the former an exception in terms of sampling density when compared to other regions/municipalities possibly due to the higher number of projects and well-structured collections. In general, municipalities were under-sampled, and taxonomic groups, especially pteridophytes <i>s.lat.</i> and gymnosperms were underrepresented in the analyzed records. Angiosperms, especially legumes, represent the largest group, with collections distributed throughout the Maranhão Amazon. It is urgent to fill in the gaps identified here for the future establishment of conservation units and the recognition of Brazilian biodiversity.databda