Plant Ecology and Evolution 154(3): 483-496, doi: 10.5091/plecevo.2021.1823
Taxonomic description and pollination ecology of Cyrtorchis okuensis (Orchidaceae, Angraecinae), a new species endemic to the Cameroon Volcanic Line
expand article infoLaura N. Azandi, Tariq Stévart§|, Bonaventure Sonké#, Murielle Simo-Droissart, Tania D’haijère¤, Vincent Droissart«
‡ Plant Systematics and Ecology Laboratory, Higher Teachers’ Training College, University of Yaoundé I, Yaoundé, Cameroon§ Missouri Botanical Garden / Université Libre de Bruxelles, Brussels, Belgium| Missouri Botanical Garden, Africa & Madagascar Department, St. Louis, United States of America¶ University of Yaoundé I, Yaoundé, Cameroon# University of Yaoundé I, Ecole Normale Supérieure, Yoaundé, Cameroon¤ Herbarium et Bibliothèque de Botanique africaine, Université Libre de Bruxelles, Brussels, Belgium« Institut de Recherche pour le Développement, Montpellier, France
Open Access

Background and aims – A recent taxonomic and molecular study of the genus Cyrtorchis revealed three new species. Here, we describe one of these new species, endemic to the Cameroon Volcanic Line (CVL), and compare it to its closest relatives. Its conservation status is provided along with detailed information on its ecology and reproductive biology.

Material and methods – A detailed examination of 21 herbarium specimens was performed using standard practices of herbarium taxonomy. The conservation status of the new species was assessed using the IUCN Red List Categories and Criteria. Furthermore, we investigated the reproductive biology of the new species in an easily accessible subpopulation in Cameroon and tested the hypothesis of hawkmoth pollination in the genus Cyrtorchis.

Key results – The newly discovered species, here named C. okuensis, is restricted to the montane forest (1600 to 2500 m elevation) of the CVL and is currently assessed as Near Threatened (NT). Among angraecoid orchids in which hawkmoth pollination is recorded (~16 species), C. okuensis has the shortest nectar spur (19–40 mm). In situ observations revealed hawkmoths with short proboscis of the genus Hippotion (H. celerio, H. eson, and H. osiris) as the main pollinators. The rate of pollination and fruiting under natural conditions was low and among the 448 surveyed flowers only 38.8% (174/448 flowers) had their pollinia removed, 19% produced fruits (87/448 flowers), and 16% (70/448 flowers) set mature fruits.

ConclusionCyrtorchis okuensis is clearly differentiated from C. submontana by its longer and wider floral bracts, longer anther caps, and wider triangular dorsal sepal.

angraecoid orchids, epiphyte, hawkmoth, IUCN Red List Categories and Criteria, pollination, systematics


  • Alexandersson R. & Johnson S.D. 2002. Pollinator-mediated selection on flower-tube length in a hawkmoth-pollinated Gladiolus (Iridaceae). Proceedings of the Royal Society of London Series B: Biological Sciences 269: 631–636.
  • Amorim F.W., Wyatt G.E. & Sazima M. 2014. Low abundance of long-tongued pollinators leads to pollen limitation in four specialized hawkmoth-pollinated plants in the Atlantic Rain Forest, Brazil. Naturwissenschaften 101(11): 893–905.
  • Asanga C. 2002. Case study of exemplary forest management in Central Africa: community forest management at the Kilum-Ijim mountain forest region, Cameroon. Food and Agricultural Organization of the United Nations, Forestry Department.
  • Ashworth L., Aguilar R., Martén-Rodríguez S., et al. 2015. Pollination syndromes: a global pattern of convergent evolution driven by the most effective pollinator. In: Pontarotti P. (ed.) Evolutionary biology: biodiversification from genotype to phenotype: 203–224. Springer, Cham.
  • Avana-Tientcheu M.L., Momo Solefack M.C., Kamga Y.B. & Nguetsop V.F. 2018. Vulnerability assessment of Gnidia glauca (Thymelaeaceae) exploitation, traditional uses and domestication potential in the community forest of Kilum-Ijim, North Western Cameroon. Journal of Ecology and The Natural Environment 10(8): 182–191.
  • Avana M.L. 2006. Domestication de Prunus africana (Hook.f.) Kalkam (Rosaceae): étude de la germination et du bouturage. PhD thesis, Université de Yaoundé, Cameroon.
  • Ayonghe S.N., Mafany G.T., Ntasin E. & Samalang P. 1999. Seismically activated swarm of landslides, tension cracks, and a rockfall after heavy rainfall in Bafaka, Cameroon. Natural Hazards 19(1): 13–27.
  • Azandi L., Stevart T., Sonké B., Simo-Droissart M., Avana M.L. & Droissart V. 2016. Synoptic revision of the genus Cyrtorchis Schltr. (Angraecinae, Orchidaceae) in Central Africa, with the description of a new species restricted to submontane vegetation. Phytotaxa 267(3): 165–186.
  • Azandi L., Droissart V., Sonké B., et al. 2021. A near comprehensive phylogenetic framework gives new insights towards a natural classification of the African genus Cyrtorchis (Angraecinae, Orchidaceae). Taxon: 1–27.
  • Bachman S., Moat J., Hill A. W., de la Torre J., & Scott B. 2011. Supporting Red List threat assessments with GeoCAT: geospatial conservation assessment tool. In: Smith V. & Penel L. (eds) e-Infrastructures for data publishing in biodiversity science. ZooKeys 150: 117–126.
  • Barthlott W., Mutke J., Rafiqpoor D., Kier G. & Kreft H. 2005. Global centers of vascular plant diversity. Nova Acta Leopoldina 92: 61–83.
  • Beentje H. 2010. The Kew plant glossary, an illustrated dictionary of plant terms. Royal Botanic Gardens, Kew, Richmond.
  • Cable S. & Cheek M. 1998. The plants of Mount Cameroon: a conservation checklist. Royal Botanic Gardens, Kew, Richmond.
  • Cheek M., Onana J.-M. & Pollard B.J. 2000. The plants of Mount Oku and the Ijim Ridge, a conservation checklist. Royal Botanic Gardens, Kew, Richmond.
  • Cheek M., Pollard B.J., Darbyshire I., Onana J.-M. & Wild C. 2004. The plants of Kupe, Mwanenguba and the Bakossi Mountains, Cameroon: a conservation checklist. Royal Botanic Gardens, Kew, Richmond.
  • Cribb P.J. 1989. Orchidaceae 3. In: Polhill R.M. (ed.) Flora of Tropical East Africa: 413–651. Balkema, Rotterdam.
  • Cunningham A.B. 2005. CITES significant trade review of Prunus africana. In: Review of Significant Trade in specimens of Appendix-II species. Sixteenth meeting of the Plants Committee, Lima (Peru), 3–8 July 2006. PC16 Doc.10.2: 3–55. Available from [accessed 3 Nov. 2021].
  • Darbyshire I., Anderson S., Asatryan A., et al. 2017. Important plant areas: revised selection criteria for a global approach to plant conservation. Biodiversity and Conservation 26: 1767–1800.
  • Dressler R.L. 1981. The orchids: natural history and classification. Harvard University Press, Cambridge.
  • Droissart V. 2009. Etude taxonomique et biogéographique des plantes endémiques d’Afrique centrale atlantique: le cas des Orchidaceae. PhD thesis, Université Libre de Bruxelles, Belgium.
  • Droissart V., Dauby G., Hardy O.J., et al. 2018. Beyond trees: biogeographical regionalization of tropical Africa. Journal of Biogeography 45(5): 1153–1167.
  • Dytham C. 2011. Choosing and using statistics. A biologist’s guide, Third edition. Wiley-Blackwell Science Ldt, USA.
  • Ellis A.G. & Johnson S.D. 2010. Gender differences in the effects of floral spur length manipulation on fitness in a hermaphrodite orchid. International Journal of Plant Science 171 (9): 1010–1019.
  • ESRI 2017. ArcGIS for desktop. Version 10.5.1. ESRI, Redlands, CA.
  • Farminhão J.N.M., Verlynde S., Kaymak E., et al. 2021. Rapid radiation of angraecoids (Orchidaceae, Angraecinae) in tropical Africa characterised by multiple karyotypic shifts under major environmental instability. Molecular Phylogenetics and Evolution 159(4): 107105.
  • Franke T. 2004. Afrothismia saingei (Burmanniaceae), a new myco-heterotrophic plant from Cameroon. Systematics and Geography of Plants 74: 27–33.
  • Frodin D.G. 2001. Guide to standard floras of the world: an annotated, geographically arranged systematic bibliography of the principal floras, enumerations, checklists and chorological atlases of different areas. Cambridge University Press, Cambridge.
  • Ghosh S., Patil S., Ahire M., et al. 2012. Gnidia glauca flower extract mediated synthesis of gold nanoparticles and evaluation of its chemocatalytic potential. Journal of Nanobiotechnology 10(1): 17.
  • Harvey Y., Pollard B.J., Darbyshire I., Onana J.-M. & Cheek M. 2004. The plants of Bali Ngemba Forest Reserve, Cameroon: a conservation checklist. Royal Botanic Gardens, Kew, Richmond.
  • IUCN 2012. IUCN Red List Categories and Criteria. Version 3.1. Second edition. Available from [accessed 1 Mar. 2020].
  • IUCN 2019. Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Available from [accessed 1 Mar. 2020].
  • IUCN 2020. The IUCN Red List of Threatened Species. Version 2020-1. Available from [accessed 4 Jun. 2020].
  • Johnson L.A. & Raguso R.A. 2016. The long-tongued hawkmoth pollinator niche for native and invasive plants in Africa. Annals of Botany 117: 25–36.
  • Johnson S.D., More M., Amorim F.W., et al. 2017. The long and the short of it: a global analysis of hawkmoth pollination niches and interaction networks. Functional Ecology 31: 101–115.
  • Luyt R. & Johnson S.D. 2001. Hawkmoth pollination of the African epiphytic orchid Mystacidium venosum, with special reference to flower and pollen longevity. Plant Systematic and Evolution 228: 49–62.
  • Martins D.J. & Johnson S.D. 2007. Hawkmoth pollination of aerangoid orchids in Kenya, with special reference to nectar sugar concentration gradients in the floral spurs. American Journal of Botany 94(4): 650–659.
  • Martins D.J. & Johnson S.D. 2013. Interactions between hawkmoths and flowering plants in east africa: polyphagy and evolutionary specialization in an ecological context. Biological Journal of the Linnean Society 110: 199–213.
  • McDonald J.H. 2014. Handbook of biological statistics. Third edition. Sparky House Publishing, Baltimore, Maryland.
  • Momo S.M.C., Kamga Y.B., Nguetsop V.F., Tiokeng B., Avana-Tientcheu M.L. & Kemeuze V.A. 2017. Diversité floristique et variation altitudinale de la structure des formations a Gnidia glauca (Fresen) Gilg. dans les forêts communautaires de KilumIjim (Nord-Ouest Cameroun). European Scientific Journal 13(6): 17–37.
  • Myers N., Mittermeier R.A., Mittermeier C.G., da Fonseca G.A.B. & Kent J. 2000. Biodiversity hotspots for conservation priorities. Nature 403: 853–858.
  • Nilsson L.A., Jonsson L., Rason L. & Randrianjohany E. 1985. Monophily and pollination mechanisms in Angraecum arachnites Schltr. (Orchidaceae) in a guild of long-tongued hawk-moths (Sphingidae) in Madagascar. Biological Journal of the Linnean Society 26(1): 1–19.
  • Nilsson L.A., Johnsson L., Ralison L. & Randrianjohany E. 1987. Angraecoid orchids and hawkmoths in central Madagascar: specialized pollination systems and generalist foragers. Biotropica 19(4): 310–318.
  • Nilsson L.A., Rabakonandrianina E. & Pettersson B. 1992. Exact tracking of pollen transfer and mating in plants. Nature 360: 666–668.
  • Nsom C.L. & Dick J. 1992. An ethnobotanical tree survey of the Kom area. Unpublished document. Ijim Mountain Forest Project.
  • Onana J.M. & Cheek M. 2011. The Red data book of the flowering plants of Cameroon. Royal Botanic Gardens, Kew, Richmond.
  • Peter C.I. & Venter N. 2017. Generalist, settling moth pollination in the endemic South African twig epiphyte, Mystacidium pusillum Harv. (Orchidaceae). Flora 232: 16–21.
  • R Core Team 2020. R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. Available from [accessed 10 Aug. 2021].
  • Royston J.P. 1982. An extension of Shapiro and Wilk’s W test for normality to large samples. Applied Statistics 31: 115–124.
  • Sainge M.N., Franke T. & Agerer R. 2005. Afrothismia korupensis (Burmanniaceae, tribe Thismieae) from Korup National Park, Cameroon. Wildenowia 35: 287–291.
  • Sainge M.N., Franke T., Merckx V. & Onana J.-M. 2010. Distribution of myco-heterotrophic (saprophytic) plants of Cameroon. In: van der Burgt X., van der Maesen J. & Onana J.-M. (eds) Systematics and conservation of African plants: 279–286. Royal Botanic Gardens, Kew, Richmond.
  • Sainge M.N. 2012. Systematics and Ecology of Thismiaceae of Cameroon. MSc thesis, University of Buea, Cameroon.
  • Sainge M.N. 2016. Patterns of distribution and endemism of plants in the Cameroon Mountains: a case study of Protected Areas in Cameroon: Rumpi Hills Forest Reserve (RHFR) and the Kimbi Fungom National Park (KFNP). Technical Report, Tropical Plant Exploration Group (TroPEG), Buea, Cameroon.
  • Sainge M.N., Onana J.-M., Nchu F., Kenfack D. & Peterson A.T. 2017. Botanical sampling gaps across the Cameroon Mountains. Biodiversity Informatics 12: 76–83.
  • Senapathi D., Biesmeijer J.C., Breeze T.D., Kleijn D., Potts S.G. & Carvalheiro L.G. 2015. Pollinator conservation - The difference between managing for pollination services and preserving pollinator diversity. Current Opinion in Insect Science 12: 93–101.
  • Simo-Droissart M., Plunkett G.M., Droissart V., et al. 2018. New phylogenetic insights toward developing a natural generic classification of African angraecoid orchids (Vandeae, Orchidaceae). Molecular Phylogenetics and Evolution 126: 241–249.
  • Stévart T. 2003. Etude taxonomique, écologique et phytogéographique des Orchidaceae en Afrique centrale atlantique. PhD thesis,Université Libre de Bruxelles, Belgium.
  • Stévart T., Akouangou E., Andriamahefarivo L., et al. 2020. The Missouri Botanical Garden. In: Hermans J., Hermans C., Linsky J. & Li C.W. (eds) World orchid collections: 26–43. Taiwan Orchid Growers Association, Tainan, Taiwan.
  • Stewart K.M. 2003. The African cherry (Prunus africana): can lessons be learned from an over-exploited medicinal tree? Journal of Ethnopharmacology 89(1): 3–13.
  • Systematics Association Committee for Descriptive Biological Terminology 1962a. II. Terminology of simple symmetrical plane shapes (chart 1a). Taxon 11: 145–148.
  • Systematics Association Committee for Descriptive Biological Terminology 1962b. IIa. Terminology of simple symmetrical plane shapes (chart 1), addendum. Taxon 11: 245–245.
  • Thiers B. continuously updated. Index Herbariorum: a global directory of public herbaria and associated staff, New York Botanical Garden’s Virtual Herbarium. Available from: [accessed 5 Feb. 2014].
  • Vogel S. 2012. Floral biological syndromes as elements of diversity within tribes in the flora of South Africa. Shaker, Aachen.
  • Wasserthal L.T. 1997. The pollinators of the Malagasy star orchids Angraecum sesquipedale, A. sororium and A. compactum and the evolution of extremely long spurs by pollinator shift. Botanica Acta 110 (5): 343–359.