<i>Begonia blaan</i> (Begoniaceae, sect. <i>Petermannia</i>), a new species from the Island of Mindanao, southern Philippines

A new species to science, Begonia blaan Naive sp. nov., discovered by a citizen scientist and posted on Facebook, is herein described and illustrated. This species closely resembles B. quercifolia but can be distinguished by its sparsely scabrid stem, falcately ovate and glabrous stipules, deciduous floral bracts, and 2‐flowered, pedunculate pistillate flowers. Below, we provide a detailed description, color plates, and information on phenology, habitat, geographical distribution, and a preliminary conservation assessment.