ABOVE: Ficus callosa growing next to the Tuaran River in west Sabah. This fig tree is part of a grove of old trees next to a graveyard on the far side of the suspension bridge that crosses the river to give access to the Tuaran Rubber Estate. This bridge is only 3 minutes drive north of Tuaran town.  Ficus callosa  is locally common in many areas of Sabah including Signal Hill, Kota Kinabalu,  Kota Belud, the Tenom valley and Sandakan. There is one record from Brunei  but this is a mistake. The only record from Sarawak is  from the  Talang Talang turtle islands not far from Kuching. There is also one suspect record  from Kalimantan.
Note: Botanists often mistake F. callosa for Artocarpus trees (eg. Terap)  which are much more common, but Artocarpus fruit are very different apart from the fig mimic Artocarpus nitidus.
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Ficus callosa growing at the base of Signal Hill opposite Tong Hing Supermarket in the center of Kota Kinabalu, Sabah. This is a relatively young tree. Older trees tend to lose their lower branches as they grow older. 
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Ficus callosa saplings are easy to recognize from their distinctive large glossy  lobed leaves, quite unlike the adult leaf.
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Ficus callosa fruit on a small tree next to the Signal Hill viewpoint platform, Kota Kinabalu. The figs ripen green and are targeted at dispersal by fruit bats, which snatch the ripe figs as they fly past.
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Ficus callosa leaves and ripe figs. The figs ripen green or green/yellow and are eaten and dispersed by  civets including Binturongs and fruit bats

Sex: As with all the other 4 species of Section Oreosycea figs found in Borneo Ficus callosa is monoecious (bisexual) with figs producing seeds as well as acting as brood chambers for fig wasps.Callosa and albipila -Final Copy

Ficus callosa World Range: A patchy distribution from S. India  and Sri Lanka east to the Philippines south to Java and east to Timor. Not found in Singapore, southern Borneo, southern Sulawesi  and northern Sumatra. The map appears to show a relict distribution indicating that Ficus callosa was once much more widespread but has only survived in the drier  more open areas of the original range. Range map from Corner (1970)