Bryophytes of the Serra dos Órgãos National Park: endemism and conservation in the Atlantic Forest.

This study presents a comprehensive inventory of bryophytes in Serra dos Órgãos National Park (PARNASO), aiming to evaluate species richness, floristic composition and threatened taxa. Despite the state of Rio de Janeiro being one of the most extensively sampled regions for bryophytes in Brazil, detailed surveys of its conservation units remain scarce. Data were obtained through bibliographic review, herbarium specimen analysis, and new field collections. A total of 507 species were recorded, belonging to 206 genera and 77 families, including 17 new records for the state. The Park harbors three locally endemic species, eight endemic to Rio de Janeiro, and 69 species endemic to Brazil. Additionally, eleven species were identified as threatened, comprising seven Endangered (EN), two Critically Endangered (CR), and two Vulnerable (VU). Montane Forest showed the highest species richness, followed by High-altitude Fields, Upper-montane Forest, and Sub-montane Forest. The findings highlight PARNASO's importance in preserving bryophyte diversity in a highly biodiverse yet understudied region. This work contributes valuable baseline data to support conservation strategies and future ecological studies in Atlantic Forest remnants.