Castanopsis densinervia is a species of tree that can grow up to 30 m tall and 50 cm in diameter. Its bark is smooth and greyish in colour while the inner bark is greyish turning to dark grey on exposure to sunlight. The colour of the sapwood is dark grey on exposure to sunlight. This tree has sparsely covered with large lenticels twigs. The thick-coriaceous leaves are glabrous (smooth) and shining on the above and densely brown tomentose (covered with matted woolly hairs) or pilose (covered with long soft hairs). The petioles are about 10 to 15 mm long. The male flowers are arranged in clusters of 3 along the rachis with acute perianth lobes while the female flowers are arranged in solitary along the rachis with obtuse perianth lobes. There is only one ovoid seed with thin wall in each subglobose (nearly globe-shaped) cupule (Soepadmo & Saw, 2000).

Castanopsis densinervia is endemic to Borneo. In Sabah, it is recorded mainly from Mt. Kinabalu in Ranau and Kimanis road in Keningau districts. There is no record from Sarawak so far. This species can be found in the primary hill mixed dipterocarp forest to lower montane forest at 1000 to 1800 m altitude (Soepadmo & Saw, 2000).