I was pretty confused about this rainforest shrub/tree for a while until I was told this is Hedraianthera porphyropetala. Quite a mouthful of a botanical name.
In many respects this tree or shrub looks like a species of Glochidion from the Phyllanthus family (Phyllanthaceae), because the leaves are alternate in a plane, there are stipules and even the flowers are axillary like a member of the Phyllanthaceae. But I guess strictly speaking botanically, the floral structure places this plant under the Celastraceae.
The twigs of many Celastraceae tend to be whitish, so maybe that could help too.
Leaf Whispering in the Tropics 