On the distinction of Atractocarpus heterophyllus and A. bracteatus (Rubiaceae): in search of the correct name for the type species of Atractocarpus
Résumé
Atractocarpus Schltr. & K.Krause is an Australian and Pacific genus of Gardenieae (Rubiaceae) which includes c. 40 species. The genus was initially described for a species bearing fusiform fruits, and occurring in the southern part of New Caledonia, viz. A. bracteatus Schltr. & K.Krause. Another species, A. heterophyllus (Montrouz.) Guillaumin & Beauvis. with oblong leaves and oblong ovoid fruits was described for New Caledonia, but initially under Gardenia Ellis and this for the North of the archipelago. During later revisions and supplementary descriptions of species in the genus, both species carrying heteromorphic leaves were reconsidered. The name A. bracteatus was placed in synonymy of A. heterophyllus; while keeping a delimitation of the species restricted to the southeastern populations. This situation ended in the re-description of the northern species, named A. balansaeanus Guillaumin. The results of the present work, based on the examination of herbarium specimens and literature, disentangles the collusion for A. heterophyllus vs A. bracteatus. Hence, the correct name typifying Atractocarpus is A. bracteatus. In regard to the destruction of the holotype for A. bracteatus in Berlin (B) and of two of the syntypes for A. heterophyllus in Lyon (LYJB), typifications for these species names are proposed. To clarify their taxonomy, complete descriptions, lists of specimens and illustrations are provided for both species.