The French Polynesian Atractocarpus Schltr. & K.Krause (Rubiaceae): circumscription of A. tahitensis and description of A. teamotuaitaui sp. nov., both microendemic and critically endangered species in the Society Islands

French Polynesia possesses the most eastward species of the genus Atractocarpus Schltr. & K.Krause in the Pacific Ocean. The genus was known from a single species in the Society Islands, Atractocarpus tahitensis (Nadeaud) Puttock, restricted to Tahiti and Raiatea. The species remained unseen there for more than a century. Field prospections from poorly explored altitudinal areas of Tahiti Nui allowed to find new populations of the species. Moreover, another taxon bearing very atypical features, including shortly petiolate and basally cordate leaves (vs long petiolate and basally attenuate leaves), is here recognized and described as a species new to science, Atractocarpus teamotuaitaui sp. nov., restricted to Tahiti’s peninsula (Tahiti Iti). An identification key to species is provided, as well as a list of specimens, a morphological description, information on their phenology, distribution and ecology. Photos are presented for each species.