Pleiospermium longisepalum (also known as Banguey Island orangeaster)[2] is a species of plant in the family Rutaceae.

[3] It is endemic to the state of Sabah on the island of Borneo.

Pleiospermium longisepalum is a shrub or small tree, growing up to 15 metres tall.

[1] Pleiospermium longisepalum is common in lowland and foothill forests and lower montane forests of Kota Marudu, Ranau, and Tambunan districts, growing up to 1,300 metres elevation.

[1] It is typically found on hill slopes and near streams in primary and secondary rain forests.