Pseuduvaria borneensis is a species of plant in the family Annonaceae. It is endemic to Borneo. Yvonne Chuan Fang Su and Richard M.K. Saunders, the botanists who first formally described the species, named it after the regions of Borneo where it is distributed including East Kalimantan, Sabah and Sarawak.
It is a tree reaching in height. Its branches have sparse lenticels. Its papery leaves are 13âÂÂ20 by 3.5âÂÂ8 centimeters and come to a point at their tips. The leaves are hairless on their upper surface and densely hairy on their lower surfaces. The leaves have 10âÂÂ16 pairs of secondary veins emanating from their midribs. Its hairy petioles are 5âÂÂ15 millimeters long with a groove on their upper side. Inflorescences are organized on short inconspicuous peduncles. Each inflorescence consists of 1âÂÂ2 flowers. Each flower is on a densely hairy pedicel 4âÂÂ9 millimeters in length. The flowers unisexual. Its flowers have 3 sepals, 2âÂÂ3 by 1.5âÂÂ3 millimeters. The sepals are smooth on their upper surface, hairy on their lower surface, and have fine hairs on their margins. Its 6 petals are arranged in two rows of 3. The outer elliptical petals are 3âÂÂ7.5 by 3.7.5 millimeters with smooth upper surfaces and densely hairy lower surfaces. The outer petals vary in color from light green to purple. The inner petals have a 4âÂÂ9 millimeter long claw at their base and a 8âÂÂ19 by 4âÂÂ8 millimeter blade. The inner petals are smooth on their upper surface, densely hairy on their lower surface and have hairy margins. The inner surfaces of the inner petals have numerous distinctive glands. Male flowers have 100âÂÂ143 stamens that are 0.6âÂÂ1.1 millimeters long. Female flowers have up to 15 carpels per flower and 6âÂÂ7 ovules per carpel. Fruit are on pedicels 5âÂÂ21 millimeters in length. The fruit consists of up to 6 monocarps. Each mature monocarp is a 24âÂÂ34 by 23âÂÂ30 millimeter ellipsoid. The mature monocarps are green, wrinkly and have prominent ridges. Each monocarp has 6âÂÂ9 seeds. The seeds are 15âÂÂ19 by 6âÂÂ9.5 millimeters.
The pollen of P. beccarii is shed as permanent tetrads.
Pseududuvaria borneensis is endemic to Borneo. It is widespread on the island, and is found in east and north Kalimantan in Indonesian Borneo, as well as in Sabah and Sarawak in Malaysian Borneo and in Brunei. The species' estimated area of occupancy (AOO) is and its estimated extent of occurrence (EOO) is .
It grows in primary and secondary lowland rain forests from elevation. It often grows by streams on sandstone, clay, and coral limestone soils.