This curious fig growing in the greenhouse at Malesiana Tropicals, at Bau near Kuching in Sarawak has been identified as a young sapling liana of Ficus grandiflora  a  very rare root climbing fig in Section Kalosyce..

Damaged surfaces produce copious latex and there is a prominent stipule which indicates this plant can only be a fig.  The tessellated (tiled)  under surface of the leaf and the uneven leaf base clearly indicate that this fig belongs to Section Kalosyce  (root climbers). The closest match  is Ficus grandiflora.

Thanks to Tim Hatch and Peter Boyce for photos and information.