Deux nouvelles espèces paléo-endémiques de Pauridiantha (Rubiaceae) des Monts Udzungwa (sud de la Tanzanie)

Two new Pauridiantha (Rubiaceae) species are described and illustrated. The first is unique by its coalescent inflorescences, minute stipules, and glabrous stems. The second, P. udzungwaensis, is characterised by the absence of domatia or the presence of pocket domatia, the large number of secondary veins and the peculiar type of exotesta anatomy. The two species have Guineo-Congolian affinities and appear to be narrow endemics from the south west part of the Eastern Arc Mountains in Tanzania, i.e. the Udzungwa Mountains. While P. coalescens is at present only reported from that massif, P. udzungwaensis is also reported from the neighbouring Rungwe Mountains. The two novelties are considered to be paleoendemics of the geographical relict type, i.e. they have a geographically distinct sister taxon.