A new species of Stigmaphyllon (Malpighiaceae) is described: Stigmaphyllonpatricianum-firmenichianum Butaud. It is restricted to the coral islands of Ouvéa, Lifou and Maré in the Loyalty Islands Province (New Caledonia) and is most similar to Stigmaphyllondiscolor (Gand.) C.E.Anderson, known from New Caledonia and Solomon Islands. Previously, plants now known as Stigmaphyllonpatricianum-firmenichianum were included in Stigmaphyllontaomense (Baker f.) C.E.Anderson, endemic to the northern part of Grande-Terre and Belep Islands (New Caledonia). A new circumscription of Stigmaphyllontaomense is proposed. The regional key for New Caledonian species of Stigmaphyllon is updated.
Keywords: Loyalty Islands; Malpighiaceae; New Caledonia; Ryssopterys; Stigmaphyllon.