Leaves chartaceous, (oblong-)lanceolate, 8-13 by 1-3 cm, base cuneate, apex (narrowly) acute-acuminate; Fruits 1 per infructescence, ± fusiform, with sharp edge, 3.5-4.5 by 4.5-2 cm, fruiting pedicel 7-9 mm long, broadened to above, scar of bracteole at or above halfway.
Asia-Tropical: Borneo present, W Kalimantan present
Malesia: Borneo, known only from the type collection, 5 km SW of Uut Labang (W Kalimantan).
The slender twigs, narrow chartaceous leaves and elongate fruits, with very inconspicuous indumentum, give this subspecies a distinctive appearance within the complex entity K. kunstleri. Also, the dots on the lower leaf surface (lens!) are finer, and less confined to the smaller veins. Fruits on one twig are in different stages of development. The status of subsp. leptophylla is uncertain because it is known only from a single fruit gathering.