Petalidium mannheimerae (Acanthaceae), a new species from Namibia and South Africa, with notes on the taxonomic identity of P. parvifolium

WESSEL SWANEPOEL; LEEVI NANYENI; ABRAHAM E. VAN WYK

doi:10.11646/phytotaxa.561.1.1

Issue: Vol. 561 No. 1: 6 September 2022

Type: Article

Published: 2022-09-06

DOI: 10.11646/phytotaxa.561.1.1

Page range: 1-13

Abstract views: 25

PDF downloaded: 28

***Petalidium mannheimerae* (Acanthaceae), a new species from Namibia and South Africa, with notes on the taxonomic identity of *P. parvifolium***

WESSEL SWANEPOEL⁺⁻
LEEVI NANYENI⁺⁻
ABRAHAM E. VAN WYK⁺⁻

Independent Researcher, P.O. Box 21168, Windhoek, Namibia; H.G.W.J. Schweickerdt Herbarium, Department of Plant and Soil Sciences, University of Pretoria, Pretoria, 0002 South Africa

Ministry of Environment, Forestry and Tourism: National Botanical Research Institute (NBRI), Private Bag 13306, Windhoek, Namibia

H.G.W.J. Schweickerdt Herbarium, Department of Plant and Soil Sciences, University of Pretoria, Pretoria, 0002 South Africa; South African National Biodiversity Institute, Private Bag X101, Pretoria, 0001 South Africa

desert endemism flora Gariep Centre lectotypification Ruellieae taxonomy Eudicots

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Abstract

Petalidium mannheimerae, here described as a new species, is only known from the Gariep Centre of Plant Endemism in southern Namibia and northwestern South Africa. Apparently first collected in 1961, it grows on arid hillsides and in drainage lines. Diagnostic morphological characters for P. mannheimerae include the rigid, cylindrical distal stems, grey-brown or yellow-brown bark, puberulent vegetative parts with sparsely scattered but robust glandular and eglandular trichomes, and the solitary white flowers with the unexpanded part of the corolla tube shorter than the expanded part. A comparison of some of the more prominent features to differentiate Petalidium mannheimerae from its morphologically most similar relatives is provided. Based on IUCN Red List categories and criteria, a conservation assessment of Vulnerable VU D1 is recommended for the new species. Herbarium specimens of P. mannheimerae have long been misidentified as P. parvifolium, a rarely collected species from east-central Namibia and west-central Botswana. Lectotypes are designated for three taxa, namely P. parvifolium, P. parvifolium var. angustifolium (a synonym of P. linifolium), and P. wilmaniae (a synonym of P. parvifolium).

References

Anderson, T. (1863) An enumeration of the species of Acanthaceae from the continent of Africa and the adjacent islands. Journal of the Proceedings of the Linnean Society. Botany 7: 13–54. https://doi.org/10.1111/j.1095-8312.1863.tb01056.x
Beentje, H. (2016) The Kew plant glossary: an illustrated dictionary of plant terms, 2nd ed. Kew Publishing, Kew, 184 pp.
Clarke, C.B. (1912) Acanthaceae. In: Thiselton-Dyer, W.T. (ed.) Flora Capensis 5 (1). L. Reeve, London, pp. 1–92. https://doi.org/10.5962/bhl.title.821
Edwards, D. & Leistner, O.A. (1971) A degree reference system for citing biological records in southern Africa. Mitteilungen der Botanischen Staatssammlung München 10: 501–509. [https://www.biodiversitylibrary.org/page/15185301#page/509/mode/1up]
Germishuizen, G. & Meyer, N.L. (eds.) (2003) Plants of southern Africa: an annotated checklist. Strelitzia 14. National Botanical Institute, Pretoria, 1231 pp.
Germishuizen, G., Meyer, N.L., Steenkamp, Y. & Keith, M. (eds.) (2006) A checklist of South African plants. Southern African Botanical Diversity Network Report 41. SABONET, Pretoria, 1126 pp.
IUCN (2012) IUCN red list categories and criteria: Version 3.1. 2nd edn. Gland, Switzerland and Cambridge U.K., iv + 32 pp.
Manktelow, M. (2000) The filament curtain: a structure important to systematics and pollination biology in the Acanthaceae. Botanical Journal of the Linnean Society 133: 129–160. https://doi.org/10.1111/j.1095-8339.2000.tb01539.x
McNeill, J. (2014) Holotype specimens and type citations: general issues. Taxon 63 (5): 1112–1113. https://doi.org/10.12705/635.7
Mendelsohn, J., Jarvis, A., Roberts, C. & Robertson, T. (2002) Atlas of Namibia. Philip, Cape Town, 200 pp.
Meyer, P.G. (1961) Beiträge zur Kenntnis der Acanthaceen Südwestafricas (II). Mitteilungen der Botanschen Staatssammlung München 4: 59–72. [https://www.biodiversitylibrary.org/item/52384#page/747/mode/1up]
Meyer, P.G. (1968) Acanthaceae. Prodromus einer Flora von Südwestafrica 130: 1–65.
Nees von Esenbeck, C.G. (1832) Acanthaceae India Orientalis. In: N. Wallich (ed.) Plantae Asiaticae rariores: or descriptions and figures of a select number of unpublished East Indian plants, vol. 3. Treuttel & Würtz, London, pp. 41–117. https://doi.org/10.5962/bhl.title.468
Obermeijer, A.A. (1936) The South African species of Petalidium. Annals of the Transvaal Museum 18: 151–162.
Schinz, H. (1926) Acanthaceae. Vierteljahrsschrift der Naturforschenden Gesellschaft in Zürich 71: 145–146.
Snijman, D.A. (2013) Acanthaceae, In: Snijman, D.A. (ed.) Plants of the Greater Cape Floristic Region, vol. 2: the Extra Cape flora. Strelitzia 30. South African National Biodiversity Institute, Pretoria, pp. 162–164.
Swanepoel, W. (2020) Petalidium kaokoense (Acanthaceae), a new species from Namibia. Phytotaxa 468 (3): 236–242. https://doi.org/10.11646/phytotaxa.468.3.1
Swanepoel, W. (2022) Petalidium sesfonteinense (Acanthaceae), a new species from the Kaokoveld, Namibia. Phytotaxa 549 (2): 127–135. https://doi.org/10.11646/phytotaxa.549.2.1
Thiers, B. (2019) Index Herbariorum: A global directory of public herbaria and associated staff. New York Botanical Garden’s Virtual Herbarium. Available from http://sweetgum.nybg.org/ih/ (accessed August 2019)
Tripp, E.A., Tsai, Y.E., Zhuang, Y. & Dexter, K.G. (2017) RADseq dataset with 90% missing data fully resolves recent radiation of Petalidium (Acanthaceae) in the ultra-arid deserts of Namibia. Ecology and Evolution 7: 1–17. https://doi.org/10.1002/ece3.3274
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. (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
Van Wyk, A.E. & Smith, G.F. (2001) Regions of floristic endemism in southern Africa: a review with emphasis on succulents. Umdaus Press, Hatfield, Pretoria, 199 pp.
Vollesen, K. (2013) Acanthaceae. In: Timberlake, J.R. & Martins, E.S. (eds.) Flora Zambesiaca 8 (5). Royal Botanic Gardens, Kew, pp. 1–177.
Willdenow, C.L. (1800) Species Plantarum, editio quarta, tomus III. Nauk, Berolini, 847 pp. https://doi.org/10.5962/bhl.title.37657