Atractocarpus decorus is a plant in the coffee family Rubiaceae which is endemic to New Guinea. Like many others in the genus, it has glossy dark green leaves and attractive white flowers.
Atractocarpus decorus is a large shrub or small tree growing up to high. It has large leaves arranged in opposite pairs on the twigs, measuring up to long by up to wide. They are glossy dark green above and lighter below with 9 to 13 prominent lateral veins each side of the midrib. The female inflorescence consists of a single flower whereas the male inflorescence has between 15 and 30 flowers. Flowers are white with 5 petals, about long and across; the orange fruit is a solitary drupe about long and diameter.
The species was first described in 1925 as Randia decora by Theodoric Valeton, based on material collected across New Guinea by the German botanist Rudolf Schlechter and Swiss botanist between 1901 and 1912. In a major review of the genus Atractocarpus in 1999 by Christopher Puttock, this species was transferred to Atractocarpus.
The genus name Atractocarpus is derived from the Ancient Greek terms átraktos, meaning "spindle", and karpós meaning "fruit", and refers to the spindle-shaped fruit of the type species. The species epithet decorus is a Latin word meaning "elegant" or "beautiful".
This species is endemic to New Guinea, and grows in numerous locations on the island at altitudes from near sea level to at least .
This species was assessed by the International Union for Conservation of Nature (IUCN) in 2018 and given the status of least concern. In its justification statement, the IUCN states "It is a widespread common species with an extent of occurrence exceeding the boundaries for a threatened category under criterion B. No major threats to the species have been identified and population is currently stable".