Since the rejection of Plectronia L. versus Olinia Thunb. (Oliniaceae), some species of Rubiaceae described within this former genus have never been transferred into correct genera. The species Plectronia paradoxa Virot, endemic to New Caledonia, is a Psydrax Gaertn., based on morphological data. A new combination is established, the description completed with the fruit characters and a drawing is provided. The presence of swollen internodes along terminal branchlets refers to a co-evolution between this plant and ants, which represents the first record of myrmecophily in the New Caledonian Rubiaceae, and the first myrmecophilous Psydrax outside Africa.
Rubiaceae, Vanguerieae, Psydrax paradoxa, combination, New Caledonia, myrmecophily