New taxonomic and conservation status of Ossiculum (Vandeae, Orchidaceae), a highly threatened and narrow-endemic angraecoid orchid from Central Africa Author Simo-Droissart, Murielle Plant Systematics and Ecology Laboratory, Higher Teachers' Training College, University of Yaounde I, P. O. Box 047, Yaounde, Cameroon murielle.simo@gmail.com Author Stevart, Tariq Missouri Botanical Garden, Africa and Madagascar Department, P. O. Box 299, St. Louis, Missouri 63166 - 0299, U. S. A & Herbarium et Bibliotheque de Botanique africaine, C. P. 265, Universite Libre de Bruxelles, Campus de la Plaine, Boulevard du Triomphe 1050, Brussels, Belgium & Botanic Garden Meise, Domein van Bouchout, Nieuwelaan 38, B- 1860 Meise, Belgium Author Sonke, Bonaventure Plant Systematics and Ecology Laboratory, Higher Teachers' Training College, University of Yaounde I, P. O. Box 047, Yaounde, Cameroon & Missouri Botanical Garden, Africa and Madagascar Department, P. O. Box 299, St. Louis, Missouri 63166 - 0299, U. S. A & Herbarium et Bibliotheque de Botanique africaine, C. P. 265, Universite Libre de Bruxelles, Campus de la Plaine, Boulevard du Triomphe 1050, Brussels, Belgium Author Sandrine Mayogo, Plant Systematics and Ecology Laboratory, Higher Teachers' Training College, University of Yaounde I, P. O. Box 047, Yaounde, Cameroon Author Kamdem, Narcisse Plant Systematics and Ecology Laboratory, Higher Teachers' Training College, University of Yaounde I, P. O. Box 047, Yaounde, Cameroon Author Droissart, Vincent https://orcid.org/0000-0001-9798-5616 Missouri Botanical Garden, Africa and Madagascar Department, P. O. Box 299, St. Louis, Missouri 63166 - 0299, U. S. A & Herbarium et Bibliotheque de Botanique africaine, C. P. 265, Universite Libre de Bruxelles, Campus de la Plaine, Boulevard du Triomphe 1050, Brussels, Belgium & AMAP, IRD, CIRAD, CNRS, INRA, Univ Montpellier, Montpellier, France text PhytoKeys 2018 2018-05-02 98 85 97 http://dx.doi.org/10.3897/phytokeys.98.23511 journal article http://dx.doi.org/10.3897/phytokeys.98.23511 1314-2003-98-85 CB4E0026FF90611AD71D6B60FF8E160C 1244343 Calyptrochilum Kraenzl., 1895: 30 Ossiculum van der Laan & Cribb, 1986: 823. Type species: Ossiculum aurantiacum van der Laan & Cribb, 1986: 824, syn. nov. Type species. Calyptrochilum preussii Kraenzl. (1895: 30) (= Calyptrochilum emarginatum (Afzel. ex Sw.) Schltr. (1918: 84)). Basionym. Limodorum emarginatum Afzel. ex Sw.(1805: 86). Description. Epiphytic or lithophytic herbs. Stem cylindrical, erect, spreading or pendent, covered by sheathing leaf bases. Leaves coriaceous, distichous, imbricate, unequally bilobed at tip, articulate to sheathing at the base. Inflorescence axillary, few- to many-flowered, shorter than leaves; bract distichous, cucullate. Flowers white, sometimes with a green or yellow mark on labellum or bright orange with a yellow labellum. Sepals ovate-elliptic, acuminate. Petals oblanceolate, acute. Labellum entire or trilobed, spurred at base; spur geniculate in middle, clavate at tip. Column with two pollinia, pollinia attached to an ovate or horseshoe-shaped viscidium. Distribution and ecology. Calyptrochilum is a genus of three species distributed throughout tropical Africa, from sea level to 1200 m and found as epiphyte in humid evergreen forests, humid woodland, savannahs and as lithophyte.