The genus Psychotria L. (Rubiaceae) is one of the most diverse in the Pacific, including the islands of French Polynesia with 28 described endemic species. The Psychotria speciosa G. Forst. complex is evaluated, and P. speciosa is lectotypified and an epitype designated. The new combination Psychotria trichocalyx (Drake) Fosberg ex J.-Y. Meyer, Lorence & J. Florence, comb. nov., is made based on Calycosia (Uragoga) trichocalyx. The new species Psychotria paulae J.-Y. Meyer, Lorence & J. Florence, sp. nov., endemic to Tahiti (Society Islands), is described and illustrated. It differs from the closely related Psychotria speciosa by having leaves with longer petioles (up to 5 cm long), flowers fewer per inflorescence (1-3) and with longer pedicels up to 15 mm long, calyx with longer tube and short lobes, a 5-7-lobed corolla, longer fruit pedicels up to 4 cm long, and cylindrical to ovoid fruits 2-3 cm long. The conservation of this extremely rare species, known from only one locality on Tahiti and directly threatened by invasive alien plants (proposed IUCN status: CR), is a priority.
Rubiaceae, Psychotria, French Polynesia, endemism, conservation, invasive plants, lectotypification, new combination, new species.