Begonia gigang (section Petermannia: Begoniaceae), a new species from Zamboanga Peninsula, Mindanao Island, Philippines

A new species of Begonia from Zamboanga del Norte, Mindanao Island, Philippines, is described. Begonia gigang is morphologically similar to Begonia corazoniae but can be distinguished by having smaller leaves which are hirsute on both surfaces, longer panicles and peduncles, shorter pedicels for both staminate and pistillate flowers, and trigonous-ellipsoid ovary. Begonia gigang is assessed as Endangered under the IUCN Red List Categories and Criteria. A detailed description, photographs, and ecological notes, and are provided.