Ryparosa kostermansii Sleumer

Tree 14-20 m, bole 12 m, diam. 12-20 cm, somewhat fluted; buttresses 1 m high; bark grey or pale brown to dark brown-red, smooth, pitted; branchlets angular, densely covered with minute, olivaceous, appressed hairs; lenticels oblong to elongate-oblong. Leaves oblong, gradually attenuate at the apex into a rather fine, acute acumen (1-1.5 cm), cuneate at the base, firmly chartaceous, olivaceous, glabrous and dull above, cream-pallid or greyish-greenish and opaque beneath when dry, rather densely covered over the whole surface beneath with minute, fine, but rather stiff, pale, appressed hairs (well visible only by a lens), (10-)12-20 by (3-)4-7 cm; midrib slightly immersed above, very prominent and sometimes set with short strigose hairs beneath, lateral nerves erect in 2 (rarely 3, then the outermost ones faint) pairs, little prominent above, manifestly so beneath, veins ± obscurely transverse, reticulation distinct on both sides, but little prominent; petioles rather thin (1-1.5 mm), (1-)1.2-1.8 cm, densely set with olivaceous, appressed, sericeous hairs. ♂ and female flowers not yet known; developed ovaries and very young fruits several on 5-9 cm long racemes; rhachis slender, 1.5 mm diam., densely covered with olivaceous, appressed hairs. Pedicels 1 mm long, 1.5 mm diam. Immature fruit subglobose, covered with a dark-olivaceous or grey-green, short tomentum and with numerous tubercles; stigmas 2, broad-reniform, sessile, very close together on the developed ovary, 1-2 mm spaced on the submature fruit (c. 1.5 cm diam.). Seeds 1-2.

It is a tropical plant. It grows in mixed forest up to 800 m above sea level. It can be on clay or sandy soil. It grows in Borneo.