Taxonomic revision of the tribe Hymenodictyeae (Rubiaceae, Cinchonoideae)

The palaeotropical tribe Hymenodictyeae Razafim. & B. Bremer, belonging to the otherwise predominantly Neotropical subfamily Cinchonoideae  s.s. (coffee family or Rubiaceae), is revised here. The tribe as presently circumscribed contains two genera, Hymenodictyon Wall. and Paracorynanthe Capuron ex J.-F. Leroy, and is distinct from the other Cinchonoideae tribes with capsular fruits in having stipules bearing large, deciduous colleters on the margins, valvate corolla aestivation, and lenticellate capsular fruits that contain elongate, bilaterally flattened, and accrescent placentae. We recognize 22 Hymenodictyon species, including four new species ( H. antakaranensis sp. nov. , H. epiphyticum sp. nov. , H. madagascaricum sp. nov. , and H. tsingy sp. nov. ), and the two described species of Paracorynanthe . Hymenodictyon is distinguished from its sister genus, Paracorynanthe , by simple or compound spicate, racemose or thyrsoid inflorescences and corolla lobes without any appendages, rather than compound umbelliform inflorescences and corolla lobes prolonged by ciliate appendages. A full taxonomic treatment, keys, and distribution maps of all recognized Hymenodictyon and Paracorynanthe species are provided. Five lectotypes and one neotype are designated. Finally, six Hymenodictyon species are illustrated for the first time.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 331–386.