Begonia isadorae (Begoniaceae), a new endemic species from Ilha Grande, an island in southeastern Brazil, with notes on leaf anatomy

Begonia isadorae is a new species endemic to an island of Brazilian Atlantic Rainforest, a biome rich in endemism and species diversity, and it is described and illustrated herein. Begonia isadorae belongs to B. sect Pritzelia (Klotzsch) A.DC. and it is morphologically similar to B. rubropilosa A.DC. sharing the same leaf blade shape and habit but differs in its puberulous to glabrescent adaxial leaf blades (vs. scabrous), puberulous tepals (vs. squamulose), and ovary with entire placentae (vs. bilamellate). A diagnosis, description, ecological comments, taxonomic and leaf anatomy notes, illustrations, and color photographs are provided. Begonia isadorae is preliminarily classified as Vulnerable (VU) due to its very small populations and restricted distribution.