A new species from St. Eustatius, Gonolobus aloiensis (Apocynaceae, Asclepiadoideae, Gonolobinae), is described and illustrated. This new species is endemic to St. Eustatius (northern Leeward Islands) and represents the first record of the genus for the island. It exhibits morphological similarity to continental G. albomarginatus, but can be distinguished in part by abaxial leaf surfaces glabrous, calyx and corolla lobes shorter and narrower, and abaxial corolla lobes completely lacking glandular indumentum and with eglandular indumentum restricted at most to only the top two-thirds of the lobes. An amplified key to species of Gonolobus s. s. in the West Indies is provided.