Notes on cauliflory, sexual dimorphism and biogeography in Drypetes (Putranjivaceae, Malpighiales) and a taxonomic treatment for D. gabonensis and two new cauliflorous threatened species from Central Africa, D. aphanes sp. nov. and D. cauta sp. nov.
Abstract
We present a preliminary discussion about cauliflory, sexual dimorphism and biogeographic patterns in Drypetes Vahl (Putranjivaceae Endl.), focused on Africa. We also present a taxonomic treatment for two new species of cauliflorous trees of this genus from the rainforests of western Central Africa, one endemic to Gabon and known from six gatherings, D. aphanes Quintanar, D.J.Harris & Barberá sp. nov., and the other distributed in Gabon and the Republic of the Congo, D. cauta D.J.Harris, Barberá & Quintanar sp. nov., also known from another six gatherings. They are presented along with D. gabonensis Pierre ex Hutch., known from 25 gatherings made throughout western Central Africa, a species with markedly dimorphic flowers between sexes compared to the rest of the species in the genus. Specimens of these two new species have been confused with D. gabonensis due to some morphological resemblances. This treatment includes the detailed descriptions of these three species, the typification of their names, a comparative table summarizing their main morphological differences, an identification key, an illustration and information about their habitat and distribution. A provisional IUCN Red List assessment shows that D. gabonensis and D. cauta sp. nov. are ‘Vulnerable’ species, and D. aphanes sp. nov. is ‘Endangered’. After the publication of these new species, Drypetes consists of 86 species in continental Africa and the Malagasy Region and 219 species for the whole world.
References
Airy Shaw H.K. 1974. Notes on Malesian and other Asiatic Euphorbiaceae. Kew Bulletin 29: 281‒331. https://doi.org/10.2307/4108542
Airy Shaw H.K. 1975. The Euphorbiaceae of Borneo. Kew Bulletin Additional Series 4: 1‒245.
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. ZooKeys 150: 117–126. https://doi.org/10.3897/zookeys.150.2109
Chakrabarty T., Gangopadhayay M. & Balakrishnan N.P. 1997. The genus Drypetes (Euphorbiaceae) in the Indian subcontinent. Journal of Economic and Taxonomic Botany 21 (2): 251‒280.
Cheek M., Ndam N. & Budden A. 2021. Notes on the threatened lowland forests of Mt Cameroon and their endemics including Drypetes burnleyae sp. nov., with a key to species of Drypetes sect. Stipulares (Putranjivaceae). Kew Bulletin 76 (2): 223–234. https://doi.org/10.1007/s12225-021-09947-2
Couvreur T.L.P. 2015. Odd man out: why are there fewer plant species in African rain forests? Plant Systematics and Evolution 301 (5): 1299–1313. https://doi.org/10.1007/s00606-014-1180-z
De la Estrella M., Forest F., Wieringa J.J., Fougère-Danezan M. & Bruneau A. 2017. Insights on the evolutionary origin of Detarioideae, a clade of ecologically dominant tropical African trees. New Phytologist 2017: 1‒14. https://doi.org/10.1111/nph.14523
Delpy E. (del.) 18??‒19?? Tabulae Herbarii L. Pierre. Herbario Musei Parisiensis, Paris.
Dowsett-Lemaire F. 1988. Fruit choice and seed dissemination by birds and mammals in the evergreen forests of upland Malawi. Revue d'écologie 43: 251‒285.
ESRI 2000. Arcview 3.2. Environmental Systems Research Institute, Inc., Redlands, California.
Gautier-Hion A., Duplantier J.M., Quris R., Feer F., Sourd C., Decoux J.P., Dubost G., Emmons L., Erard C., Hecketsweiler P., Moungazi A., Roussilhon C. & Thiollay J.M. 1985. Fruit characters as a basis of fruit choice and seed dispersal in a tropical forest vertebrate community. Oecologia 65: 324‒337.
Harris J.G. & Harris M.W. 1994. Plant Identification Terminology. An Illustrated Glossary. Spring Lake Publishing, Spring Lake.
Harris D.J., Barberá P., Nguema D. & Quintanar A. 2021. Putranjivaceae Endl. In: Sosef M.S.M., Florence J., Bourobou H. & Bissiengou P. (eds) Flore du Gabon 57: 108‒160. Margraf Publishers, Weikersheim.
Heilbuth J.C. 2000. Lower species richness in dioecious clades. The American Naturalist 156 (3): 221‒241.
Hooker J.D. 1887. The Flora of British India 5: 336–343. L. Reeve & Co., London.
Hutchinson J. 1912. Drypetes Vahl. In: Oliver D. [Dyer W.T.T. (ed.)], Flora of tropical Africa, vol. 6 (1): 674‒689. L. Reeve & Co., London.
IUCN Standards and Petitions Committee 2022. Guidelines for Using the IUCN Red List Categories and Criteria. Version 15.1. Prepared by the Standards and Petitions Committee. IUCN, Gland, Switzerland, Cambridge, United Kingdom. Available at https://nc.iucnredlist.org/redlist/content/attachment_files/RedListGuidelines.pdf [accessed 29 Jul. 2022].
Käfer J., de Boer H.J., Mousset S., Kool A., Dufay M. & Marais G.A.B. 2014. Dioecy is associated with higher diversification rates in flowering plants. Journal of Evolutionary Biology 27: 1478‒1490. https://doi.org/10.1111/jeb.12385
Maley J. 1996. The African rain forest – main characteristics of changes in vegetation and climate from the Upper Cretaceous to the Quaternary. Proceedings of the Royal Society of Edinburgh 104: 31–73. https://doi.org/10.1017/S0269727000006114
Maley J. 2002. A catastrophic destruction of African forests about 2,500 years ago still exerts a major influence on present vegetation formations. IDS Bulletin 33: 13–30. https://doi.org/10.1111/j.1759-5436.2002.tb00003.x
Muyle A., Martin H., Zemp N., Mollion M., Gallina S., Tavares R., Silva A., Bataillon T. Widmer A., Glémin S., Touzet P. & Marais G.A.B. 2020. Dioecy is Associated with High Genetic Diversity and Adaptation Rates in the Plant Genus Silene. Molecular Biology and Evolution 38 (3): 805‒818. https://doi.org/10.1093/molbev/msaa229
Parmentier I., Malhi Y., Senterre B., Whittaker R.J., Alonso A., Balinga M.P.B., Bakayoko A., Bongers F., Chatelain C., Comiskey J.A., Cortay R., Djuikouo Kamdem M.N., Doucet J.L., Gautier L., Hawthorne W., Issembe Y.A., Kouamé F.N., Kouka L.A., Leal M.E., Lejoly J., Lewis S.L., Nusbaumer L., Parren M.P., Peh K.S.H., Phillips O.L., Sheil D., Sonké B., Sosef M.S.M., Sunderland T.C.H., Stropp J., ter Steege H., Swaine M.D., Tchouto M.G.P., van Gemerden B.S., van Valkenburg J.L.C.H. & Wöll H. 2007. The odd man out? Might climate explain the lower tree α-diversity of African rain forests relative to Amazonian rain forests? Journal of Ecology 95: 1058‒1071. https://doi.org/10.1111/j.1365-2745.2007.01273.x
Pax F.A. & Hoffmann K. 1922. Euphorbiaceae–Phyllanthoideae–Phyllantheae. In: Engler H.G.A. (ed.) Das Pflanzenreich. Regni Vegetabilis Conspectus 147, 15 (Heft 81). Verlag von Wilhelm Engelmann, Leipzig.
Pole M. 1991. A modified terminology for angiosperm leaf architecture. Journal of the Royal Society of New Zealand 21 (4): 297‒312. https://doi.org/10.1080/03036758.1991.10420828
Phuphathanaphong L. & Chayamarit K. 2005. Drypetes. In: Thawatchai S. & Larsen K. (eds) Flora of Thailand 8 (1): 231–253. The Forest Herbarium, Bangkok.
Quintanar A., Harris D.J. & Barberá P. 2020. A new species of Drypetes (Putranjivaceae) discovered by J. Léonard in the Democratic Republic of the Congo. Plant Ecology and Evolution 153: 312–320. https://doi.org/10.5091/plecevo.2020.1709
Quintanar A., Barberá P., Nguema D., Medjibe V., Goodwin Z.A., Onana J.M., Ndolo Ebika S.T., Ewango C.E.N., Moutsamboté J.M. & Harris D.J. 2021a. Lurking in the Shadows: A New Species of Drypetes (Putranjivaceae) from Central Africa Hiding in Forest Plots and Herbaria. Novon 29: 14–23. https://doi.org/10.3417/2020637
Quintanar A., Harris D.J. & Barberá P. 2021b. The Genus Drypetes (Putranjivaceae) in Liberia: An Annotated Checklist with a New Species, D. liberica. Annals of the Missouri Botanical Garden 106: 47–63. https://doi.org/10.3417/2021622
Quintanar A., Barberá P. & Harris D.J. 2022. A new species of Drypetes (Putranjivaceae) from the western Congolian swamp forest, D. palustris sp. nov. Anales del Jardín Botánico de Madrid 79 (1): e120. https://doi.org/10.3989/ajbm.2615
Quintanar A., Sonké B., Simo-Droissart M., Barberá P., Libalah M. & Harris D.J. 2023. A matter of warts: a taxonomic treatment for Drypetes verrucosa (Putranjivaceae, Malpighiales) and a new cauliflorous species from Cameroon and Nigeria, D. stevartii. Plant Ecology and Evolution 156 (2): 160‒173. https://doi.org/10.5091/plecevo.102004
Radcliffe-Smith A. 1987. Drypetes. In: Polhill R.M. (ed.) Flora of Tropical East Africa. Euphorbiaceae 1: 88–103. A.A. Balkema, Rotterdam.
Radcliffe-Smith A. 1995. Additions and corrections to ‘Euphorbiaceae’ for ‘Flora of Tropical East Africa’. Kew Bulletin 50: 809‒816. https://doi.org/10.2307/4110245
Renner S.S. 2014. The relative and absolute frequencies of angiosperm sexual systems: Dioecy, monoecy, gynodioecy, and an updated online database. American Journal of Botany 101 (10): 1588‒1596. https://doi.org/10.3732/ajb.1400196
Richards P.W. 1973. Africa, the “Odd man out”. In: Meggers B.J., Ayensu E.S. & Duckworth W.D. (eds) Tropical Forest Ecosystems in Africa and South America: a Comparative Review: 21‒26. Smithsonian Press, Washington.
Rijckevorsel P. van 2011. (6‒8) Proposals to add two Tabulae herbarii L. Pierre or the entire set to the “Opera utique oppressa”. Taxon 60: 287‒289. https://doi.org/10.1002/tax.601034
Stearn W.T. 1973. Botanical Latin. 2nd ed. David & Charles Newton Abbot, London.
Thiers B. 2020 [continuously updated]. Index Herbariorum: A global directory of public herbaria and associated staff. New York Botanical Garden’s Virtual Herbarium. Available from http://sweetgum.nybg.org/science/ih/ [accessed 29 Jul. 2022].
Thwaites G.H.K. 1855. On Sphragidia and Eccremanthus, two new Genera of Ceylon plants together with Observations on the Genus Hemicyclia. Hooker's Journal of Botany and Kew Garden Miscellany 7: 269–273.
Vamosi J.C. & Vamosi S.M. 2005. Present day risk of extinction may exacerbate the lower species richness of dioecious clades. Diversity and Distributions 11: 25‒32. https://doi.org/10.1111/j.1366-9516.2005.00119.x
Vamosi J.C. & Vamosi S.M. 2008. Extinction risk escalates in the tropics. PLoS ONE 3 (12): e3886. https://doi.org/10.1371/journal.pone.0003886
Turland N.J., Wiersema J.H., Barrie F.R., Greuter W., Hawksworth D.L., Herendeen P. S., Knapp S., Kusber W.H., Li D.Z., Marhold K., May T.W., McNeill J., Monro A.M., Prado J., Price M.J. & Smith G.F. (eds) 2018. International Code of Nomenclature for algae, fungi, and plants (Shenzhen Code). Adopted by the Nineteenth International Botanical Congress Shenzhen, China, July 2017. Regnum Vegetabile 159. Koeltz Botanical Books, Glashütten. https://doi.org/10.12705/Code.2018
Copyright (c) 2023 Alejandro Quintanar, David J. Harris, Diosdado Nguema, Patricia Barberá
This work is licensed under a Creative Commons Attribution 4.0 International License.
Creative Commons Copyright Notices
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License (CC BY 4.0) that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are NOT ALLOWED TO post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to taxonomic issues.
