New Sonerila species reported from southwest Philippines

The genus Sonerila, belonging to the plant family Melastomataceae, is represented by approximately 194 species. The genus is poorly known in the Philippines and is represented by only two species, Sonerila tenera and S. woodii.

During a botanical exploration in October 2022 at the Tabu-tabu Biodiversity Monitoring Site of Pasonanca Natural Park in Philippines, a researcher from Xishuangbanna Tropical botanical Garden (XTBG) of the Chinese Academy of Sciences collected an unknown population of Sonerila species. After a careful examination of its morphology and consultation of relevant literature and type specimens of Sonerila species from the Philippines and neighboring countries, the researcher confirmed it as a species new to science.

The new species was named as Sonerila mapelo and reported in Taiwania on Aug. 23.

Sonerila mapelo is a terrestrial to epiphytic, perennial herb. It has dimorphic leaves, axillary inflorescence and oblong anthers with emarginate apex. It can be easily distinguished from all other Philippine Sonerila for short petioles and strongly dimorphic leaves at each node. It closely resembles S. metallica but differs significantly for the following characters: both sides of the leaves densely strigose with up to six major veins, broadly cordate small leaves, etc.

Sonerila mapelo is found growing in the broad leaf montane forest as a terrestrial on moss cushions or as an epiphyte on the lower trunk of tree ferns with a moist, cool, and deeply shaded environment at an elevation between 1,100 to 1,360 meters above sea level. It is endemic to Zamboanga Peninsula, the island of Mindanao.

The researchers proposed the conservation status of the new species as vulnerable, since the species is so far only known in Tabu Tabu BMS of Pasonanca Natural Park, La Paz, Zamboanga City.