Botanical Journal of the Linnean Society, 2006, 152, 331–386. With 20 figures © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 152, 331–386 331 Blackwell Publishing LtdOxford, UKBOJBotanical Journal of the Linnean Society0024-4074The Linnean Society of London, 2006? 2006 152? 331386 Original Article REVISION OF HYMENODICTYEAE S. G. RAZAFIMANDIMBISON and B. BREMER *Corresponding author. E-mail: sylvain.razafimandimbison@bergianska.se Taxonomic revision of the tribe Hymenodictyeae (Rubiaceae, Cinchonoideae) SYLVAIN G. RAZAFIMANDIMBISON 1,2 * and BIRGITTA BREMER 1,2 1 The Bergius Foundation at the Royal Swedish Academy of Sciences, PO Box 50017, SE-10405, Stockholm, Sweden 2 Department of Botany, Stockholm University, SE-10691, Stockholm, Sweden Received October 2005; accepted for publication April 2006 The palaeotropical tribe Hymenodictyeae Razafim. & B. Bremer, belonging to the otherwise predominantly Neotro- pical 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, val- vate 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 umbel- liform inflorescences and corolla lobes prolonged by ciliate appendages. A full taxonomic treatment, keys, and dis- tribution 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. ADDITIONAL KEYWORDS: Africa – Asia – Hymenodictyon – Madagascar – Paracorynanthe – systematics – taxonomy. INTRODUCTION The tribe Hymenodictyoneae Razafim. & B. Bremer, correctly spelled by Bridson & Verdcourt (2003: 385 & 423) as Hymenodictyeae, was described by Razafiman- dimbison & Bremer (2001) to accommodate the two palaeotropical genera, Hymenodictyon Wall. and Para- corynanthe Capuron. Andersson & Persson (1991) placed these genera in the tribe Coptosapelteae, which was demonstrated by Razafimandimbison & Bremer (2001) to be highly polyphyletic. Hymenodictyeae belongs to the subfamily Cinchonoideae s.s. (Bremer et al., 1999) of the coffee family (Rubiaceae) and has been shown to be sister to the mostly palaeotropical tribe Naucleeae s.l. (Razafimandimbison & Bremer, 2002). In Andersson & Antonelli (2005) the Hymeno- dictyeae–Naucleeae clade was resolved as sister to a predominantly Neotropical clade, which contains Chiococceae sensu Bremer (1992), Cinchoneae sensu Andersson & Antonelli (2005), Guettardeae, Hame- lieae, Hillieae, Isertieae sensu Bremer & Thulin (1998), and Rondeletieae. In Razafimandimbison & Bremer (2001: 526), Paracorynanthe, represented by P. antankarana Capuron ex J.-F. Leroy, and Hymenodictyon, represented by four Hymenodictyon species [H. decaryi Homolle, H. flaccidum Wall., H. floribundum (Hochst. & Steud.) B.L. Rob., and H. parvifolium Oliv.] formed a strongly supported monophyletic group (bootstrap support value = 100%). The phylogenetic relationships within this Hymenod- ictyon–Paracorynanthe clade (= Hymenodictyeae) were unresolved. On the other hand, an unpublished phylogenetic analysis based on external transcribed spacers sequence data (S. Razafimandimbison and B.