Assessing the evolutionary distinctiveness of a highly threatened plant group: The urgency to preserve a unique lineage of evolution in Brazil

Societal Impact Statement Brazil's diverse flora is under several threats, with many unique lineages facing extinction, particularly in biodiverse regions like the Cerrado and campo rupestre . This study sheds light on the conservation needs of Cambessedesia (Melastomataceae), an endemic genus with 95% of its species endangered, using an approach to rank and prioritise species based on evolutionary distinctiveness and threat levels. By highlighting regions most affected by habitat loss and agricultural expansion, especially in the Cerrado and in the campo rupestre , this work aims to guide policies and conservation actions that protect biodiversity and evolutionary heritage, helping to prevent irreversible loss of natural history. Summary Brazil hosts the world's most diverse flora, yet this richness faces numerous threats, risking the loss of unique evolutionary history. Incomplete assessments hinder the understanding of the true extent of risk, particularly for the Cerrado and campo rupestre ecosystems ‐ hotspots of angiosperm richness and endemism, now experiencing severe habitat loss. This study examines the conservation status and evolutionary distinctiveness of Cambessedesia (Melastomataceae), with 24 endemic species, integrating data on land use and cover change. We leverage virtual herbarium specimens to assess each species' conservation status according to IUCN criteria. We analysed the loss of natural vegetation within each species' Extent of Occurrence over a 10‐year period. Then, we calculated the Evolutionary Distinct and Globally Endangered (EDGE) scores to prioritise species that are both highly threatened and evolutionarily distinct. Species distribution models were created and integrated with EDGE scores to generate species richness and diversity maps. Cambessedesia is a highly threatened genus, with 95% of species in threatened categories. Consequently, the EDGE and EDGE2 scores provide valuable metrics for ranking conservation priorities. Two areas stand out for their significant vegetation loss, both linked to land‐use changes driven by agriculture, one of which is currently the country's main agricultural frontier. Diversity maps highlight hotspots containing species with significant evolutionary history. These findings raise awareness of the uniqueness of these species and guide future conservation efforts. Urgent policies are needed to protect these evolutionarily unique lineages, especially in Cerrado and campo rupestre , where habitat loss and limited protected areas exacerbate extinction risks.