TL;DR: Kostermanthus robustus is described from the Malaysian state of Sarawak in Borneo, which is distinguished from other Malesian genera of Chrysobalanaceae by the stamens, which are united into a ligule as in the Neotropical genus Acioa and the African genus Dactyladenia.
Abstract: Kostermanthus robustus is described from the Malaysian state of Sarawak in Borneo. This is only the third species in this genus, which is distinguished from other Malesian genera of Chrysobalanaceae by the stamens, which are united into a ligule as in the Neotropical genus Acioa and the African genus Dactyladenia.
TL;DR: A phylogenetic analysis for the Chrysobalanaceae indicated that the family is a well-defined monophyletic group that is sister to Euphronia Mart.
Abstract: The Chrysobalanaceae, a pantropical family containing about 525 species, has often been nested within the Rosaceae despite evidence for recognizing it as a separate family. In 1963, Prance clearly placed Chrysobalanaceae as a distinct family containing 17 genera. However, the family has been linked with various other families and orders and recently has been placed within the order Malpighiales. Because of these discrepancies, a phylogenetic analysis for the family was launched to examine its monophyly and to investigate the relationships within the Chrysobalanaceae as well as its relationships to other groups. Comparative phylogenetic analyses were performed using morphological, rbcL, and ITS sequences. The data sets were analyzed independently and in combination. After exploration for hard incongruencies among the independent data sets, a simultaneous analysis of all the data was completed. The combined analysis resulted in a resolved, supported topology with several unambiguous morphological synapomorphies. The resulting topology indicated that the family is a well-defined monophyletic group that is sister to Euphronia Mart. & Zucc. (Euphroniaceae). The present tribal groupings, however, are paraphyletic. The Chrysobalanaceae R. Br. includes 17 genera and about 525 species. Most of these species occur in the lowlands of the tropics and subtropics, and the family is especially well represented in the New World tropics. The present family circumscription places the 17 genera in four tribes: Chrysobalaneae, which includes Chrysobalanus L., Grangeria Comm. ex Juss., Licania Aubl., and Parastemon A. DC.; Couepieae, which includes Acioa Aubl., Couepia Aubl., and Maranthes Blume; Parinarieae, which includes Bafodeya Prance ex F. White, Exellodendron Prance, Hunga Prance, Neocarya (DC.) Prance ex F. White, and Parinari Aubl.; and Hirtelleae, which includes Atuna Raf., Dactyladenia Welw., Hirtella L., Kostermanthus Prance, and Magnistipula Engl. (Prance & White, 1988) (Table 1). All species of Chrysobalanaceae are woody, and most are trees or shrubs. The vegetative architecture of the plants is relatively uniform. The flower, by contrast, is comparatively diverse, although nearly every genus is characterized by an underlying uniformity of inflorescence and floral structure. The flowers are bisexual, rarely unisexual, and markedly perigynous. The flower size and shape vary within wide limits, from minute