Tree 6-20 m. Leaves membranous or chartaceous, elliptic or oblong, 12-30(-40) by 5.5-12(—19) cm, apex acute-acuminate, base shallowly cordate to broadly rounded; Inflorescences: Fruits solitary or 2 or 3 together, oblong(-lanceolate), ± fusiform, 7 by 2 cm, base tapering, apex long-tapering or beaked, with grey-brown scale-like hairs less than 0.1 mm, appearing as if subglabrous;
Asia-Tropical: Borneo present (Sabah present), border area of NE Kalimantan present
Malesia: Borneo (Sabah, including border area of NE Kalimantan).
Knema kostermansiana may resemble K. glauca and K. pulchra. Knema glauca differs in its shorter fruits, and median bracteole, narrower leaves, and ± raised nerves; K. pulchra is distinguishable by pear-shaped, not globose, male buds and by much broader ellipsoid fruits with rounded apex. The slender, ± fusiform fruits of 7 cm length of K. kostermansiana much resemble those of K. luteola, and somewhat those of K. ashtonii var. ashtonii; both differ in a much finer venation on the upper leaf surface, the first by narrow-rounded or attenuate leaf base and generally somewhat smaller fruits (up to 70 mm long), the second in stouter habit and the fruits with ± blunt apex, not pointed.