Flora of Cameroon - Annonaceae Vol 45 Author Couvreur, Thomas L. P. https://orcid.org/0000-0002-8509-6587 IRD, DIADE, Univ Montpellier, Montpellier, France & Universite de Yaounde I, Ecole Normale Superieure, Departement des Sciences Biologiques, Laboratoire de Botanique systematique et d'Ecologie, B. P. 047, Yaounde, Cameroon & Naturalis Biodiversity Center, Botany Section, Darwinweg 2, 2333 CR Leiden, Netherlands thomas.couvreur@ird.fr Author Dagallier, Leo-Paul M. J. https://orcid.org/0000-0002-3270-1544 IRD, DIADE, Univ Montpellier, Montpellier, France Author Crozier, Francoise IRD, DIADE, Univ Montpellier, Montpellier, France Author Ghogue, Jean-Paul Universite de Yaounde I, Ecole Normale Superieure, Departement des Sciences Biologiques, Laboratoire de Botanique systematique et d'Ecologie, B. P. 047, Yaounde, Cameroon & Green Connexion, Environmental Group, siege face GP Melen, a cote de l'immeuble Palais des verres. Yaounde, Cameroun Author Hoekstra, Paul H. Naturalis Biodiversity Center, Botany Section, Darwinweg 2, 2333 CR Leiden, Netherlands Author Kamdem, Narcisse G. Universite de Yaounde I, Ecole Normale Superieure, Departement des Sciences Biologiques, Laboratoire de Botanique systematique et d'Ecologie, B. P. 047, Yaounde, Cameroon Author Johnson, David M. https://orcid.org/0000-0003-2896-7419 Department of Botany-Microbiology, Ohio Wesleyan University, Delaware, OH, 43015, USA Author Murray, Nancy A. Department of Botany-Microbiology, Ohio Wesleyan University, Delaware, OH, 43015, USA Author Sonke, Bonaventure https://orcid.org/0000-0002-4310-3603 Universite de Yaounde I, Ecole Normale Superieure, Departement des Sciences Biologiques, Laboratoire de Botanique systematique et d'Ecologie, B. P. 047, Yaounde, Cameroon text PhytoKeys 2022 2022-09-20 207 1 532 http://dx.doi.org/10.3897/phytokeys.207.61432 journal article http://dx.doi.org/10.3897/phytokeys.207.61432 1314-2003-207-1 29CD4EF8FB525DBAA022DF25CDB649C9 Isolona zenkeri Engl., Notizbl. Bot. Gart. Berlin-Dahlem 2: 301, 1899 Figs 40 , 41 ; Map 5H Type . Cameroon . South Region ; Bipindi, Zenker G.A. 1186 , 1896: holotype : B[B 10 0154218]; isotypes: BM n.v. , G[G00011574]; K[K000199013]; WU[WU0025863] . Description. Tree to shrub, 7-15 m tall, d.b.h. up to 15 cm; stilt roots or buttresses absent, trunk not fluted. Indumentum of simple hairs; old leafless branches glabrous, young foliate branches glabrous. Leaves: petiole 2-6 mm long, ca. 2 mm in diameter, glabrous, slightly grooved, blade inserted on top of the petiole ; blade 16-23 cm long, 6.5-8.5 cm wide, oblong to oblanceolate, apex abruptly acuminate, acumen 1-2 cm long, base rounded to acute, coriaceous, below glabrous when young and old, above glabrous when young and old, concolorous; midrib raised above, above glabrous when young and old, below glabrous when young and old; secondary veins 11 to 13 pairs, glabrous below; tertiary venation reticulate. Individuals bisexual; inflorescences ramiflorous on young foliate branches, axillary. Flowers with 9 perianth parts in 2 whorls, 1 to 2 per inflorescence; pedicel 3-7 mm long, ca. 1 mm in diameter, glabrous; in fruit 5-15 mm long, 2-3 mm in diameter, glabrous; bracts 2 to 4, all basal, 1 mm long, 1 mm wide; sepals 3, valvate, free, 2-5 mm long, 2-4 mm wide, ovate, apex acute, base truncate, green to brown-red, glabrous outside, glabrous inside, margins flat; petals basally fused, tube 4-7 mm long, inner and outer whorl not differentiated, equal; lobes 15-25 mm long, 3-4 mm wide, lorate (strap-shaped) to oblong, apex acute, light yellow to light green, margins curved inwards , glabrous outside, glabrous inside, erect over receptacle, verrucose when dried ; stamens ca. 40, in 3 to 4 rows, ca. 2 mm long, broad; connective discoid, glabrous, cream; staminodes absent; carpels fused into a single structure, ca. 3 mm long, stigma bilobed, slightly capitate, glabrous. Fruit syncarpous, sessile, 30-65 mm long, 15-30 mm in diameter, ellipsoid to globose, apex rounded, glabrous, smooth, faintly ribbed to longitudinally ribbed , green turning yellow when ripe; seeds not counted, 15-20 mm long, 8-10 mm in diameter, ellipsoid; aril absent. Figure 41. Isolona zenkeri A tree in rain forest B detail of funneled trunk C detail of leaves, upper side, note raised midrib D flowers, side view, note erect lobes E flowering and fruiting branch A, B Sosef 2291 , Gabon C Sosef 2350 , Gabon D, E Sosef 2322 , Gabon. Photos Thomas L.P. Couvreur. Distribution. Known from Cameroon to the west of Republic of Congo; in Cameroon known from the South and Littoral regions. Habitat. A fairly infrequent species, growing in lowland rain forests. Altitude 0-800 m a.s.l. Local and common names known in Cameroon. None recorded. IUCN conservation status. Least Concern (LC) ( Cosiaux et al. 2019x ). Uses in Cameroon. None reported. Notes. Isolona zenkeri is characterized by its coriaceous corolla lobes with incurved margins, erect above the receptacle, and verrucose when dried. Specimens examined. South Region : Bipinde, 3.26°N , 10.20°E , 16 June 1918 , Annet E. 359 (WAG); 12 km from Kribi N of Ebolowa road between Kribi aifield and Kienke R , 2.88°N , 9.983°E , 18 June 1969 , Bos J.J. 4866 (BR,K,LM,MO,P,POZG,WAG,YA); 6 km N of km Kribi-Lolodorf, 3.08°N , 10.25°E , 12 March 1970 , Bos J.J. 6522 (BR,K,P,WAG,YA); Campo-Ma'an area Bibabimvoto, 2.25°N , 10.36°E , 01 February 2000 , Elad M. 1269 (WAG); Campo-Ma'an area Ebianemeyong, 2.46°N , 10.29°E , 24 May 2002 , Elad M. 1545 (KRIBI,WAG); 3 km S of Kwambo and 6 km WSW of Bipindi , 3.05°N , 10.36°E , 19 January 1987 , Manning D. 1453 (MO); Campo-Ma'an area Bifa, 2.65°N , 10.28°E , 12 October 2001 , Tchouto Mbatchou G.P. BIFAX_2 (WAG); Campo-Ma'an area Bibabimvoto, 2.21°N , 10.01°E , 13 May 2000 , Tchouto Mbatchou G.P. 2855 (KRIBI,WAG,YA); Campo-Ma'an area Bibabimvoto, 2.25°N , 10.04°E , 24 August 2000 , Tchouto Mbatchou G.P. 3009 (KRIBI,WAG,YA); Bipindi , 3.08°N , 10.41°E , 1896 , Zenker G.A. 1186 (B,BM,G,K); Bipindi , 3.08°N , 10.42°E , 01 January 1907 , Zenker G.A. 3375 (P); Bipindi , 3.08°N , 10.41°E , 01 January 1908 , Zenker G.A. 3471 ( US ); Bipindi , 3.08°N , 10.41°E , 01 January 1912 , Zenker G.A. 4405 (G,K,MO) .