KEY TO THE SUBSPECIES

1Bark of older twigs not or hardly longitudinally cracking, nor flaking. Twig apex coarsely rusty pubescent, striate or ridged, ± angled. [Male buds pear-shaped; staminal disc ± flat above.] — Palawan.
1'Bark of older twigs usually longitudinally cracking, later on (finely) flaking (not flaking in subsp. ridleyi forma nana). Twig apex variably hairy, striate or not, not angled.
2Indumentum of twig apex and flowers dark brown. Male buds obconical or globose, often somewhat broader than long. Leaves usually large, 4-10 cm broad, drying dark (greenish) brown above, pale brown or grey-glaucous beneath. Fruits variable of size, with brown to rusty-reddish indumentum. — Peninsular Thailand and Malaysia, Bangka, Borneo.
2'Indumentum of twig apex and flowers pale or yellowish brown. Male buds obovoid. Leaves generally smaller, 11-22 by 2-5 cm, drying pale (greenish) brown above, whitish beneath. Fruits 1.4-2(-3.5) cm long, with pale or yellowish brown indumentum. — Borneo.