Fontainea subpapuana is a small tree endemic to Papua New Guinea in the family, Euphorbiaceae, which grows to a height of 7 m.[2] Fontainea subpapuana is a small dioecious tree growing to 7 m. The colour of the stem exudate is red.

The description given by Forster lacks significant details with respect to the male flowers and mature fruit.

Fontainea subpapuana is known only from the Central Province in south-east Papua New Guinea, in lowland rainforest on river flats.

[2] The plant was first described by Paul Irwin Forster in "Three new species of Fontainea Heckel (Euphorbiaceae) from Australia and Papua New Guinea".

[1][2] The holotype K000959474 was collected by H. Streiman and A, Kairo on May 6, 1971, in the Kuriva Forestry Area, near Veimauri Rr, in the Port Moresby subdistrict, Papua New Guinea, in lowland rainforest on river flats.