Alstonia costata, synonyms including Alstonia marquisensis, is a species of flowering plant in the family Apocynaceae, native to the Solomon Islands in Papuasia and to islands in the south Pacific. It was first described by Georg Forster in 1786 as Echites costatus. It grows as a shrub or tree.
Alstonia costata is native to the Solomon Islands in Papuasia; the Cook Islands, the Marquesas Islands and the Society Islands in the south-central Pacific; and Fiji, New Caledonia, Samoa, the Santa Cruz Islands, Tonga, and Vanuatu in the south-western Pacific.