Isoetes eludens (Isoetaceae), a new endemic species from the Kamiesberg, Northern Cape, South Africa
- 79 Downloads
Isoetes eludens, a new, highly localised, endemic species from the Kamiesberg, Northern Cape is described. The aquatic species grows in a shallow temporary gnamma or !gau (rock pool) in Kamiesberg gneiss at an altitude of 1,284 m. It is characterised by a short, strongly 3-lobed stem, relatively short, and broad estomate sporophylls, a complete velum, the presence of an outer sporangium sack (a feature not previously reported for the genus), graphite-black, laevigate megaspores with a narrow, but tall laesura, microspores with near smooth proximal surfaces but with a papillate distal surface, the absence of a ligule and labium, and simple roots with few root-hairs. The systematic relationship of the species is difficult to determine as a result of convergent evolution in the genus. The sporangium sack does not support an affinity with any of the known species. Further surveys are needed to establish the geographical extent and conservation status of this remarkable local endemic.
Key WordsIsoetaceae Isoetes eludens Kamiesberg Northern Cape South Africa
The first author wishes to express his thanks to SDH for bringing this unusual species to his attention. Also to Dr J. P. Rourke who accompanied us, on different occasions to the locality. Dr J. Manning, Dr D. Snijman and Dr C. Paterson-Jones have also participated in exploratory field work in the Kamiesberg. Appreciation also goes to the Department of Tourism, Environment and Conservation, Northern Cape for providing the necessary permits to collect the material in the province, and to Mr J. J. P. Beukes, owner of the farm Damsland for giving permission to study and collect the plants on his land. Michelle Smith prepared the electronic versions of the illustrations and distribution map, and Katherine Challis provided the Latin diagnosis.
- Duthie, A. V. (1929). The species of Isoetes found in the Union of South Africa. Trans. Roy. Soc. South Africa 17: 321 – 334.Google Scholar
- Hilton-Taylor, C. (1994). Western Cape Domain (Succulent Karoo). In: S. D. Davis, V. H. Heywood & A. C. Hamilton (eds), Centres of plant diversity. A guide and strategy for their conservation. Vol. 1: 204 – 217. IUCN Publications Unit, Cambridge.Google Scholar
- ____ (1996). Patterns and characteristics of the flora of the Succulent Karoo Biome, southern Africa. In: L. J. G. van der Maesen, X. M. van der Burgt & J. M. van Medebach de Rooy (eds), The biodiversity of African plants, pp. 58 – 72. Kluwer, Dordrecht.Google Scholar
- IUCN (2001). IUCN Red List of Threatened Species. 2001 Categories & Criteria (version 3.1). http://www.iucnredlist.org/info/categories_criteria2001.
- Mittermeier, R. A., Myers, N., Robles-Gil, P. & Mittermeier, C. G. (2000). Hotspots: earths biologically richest and most endangered terrestrial ecoregions. Cemex, Mexico (under auspices of Conservation International, Washington, D.C.).Google Scholar
- Rebelo, A., Boucher, C., Helme, N., Mucina, L. & Rutherford, M. C. (2006). Fynbos biome. In: L. Mucina & M. C. Rutherford (eds), The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19: 53 – 219.Google Scholar
- Roux, J. P. (2001). Conspectus of southern African Pteridophyta. Southern African Botanical Diversity Network Report No. 13. SABONET, Pretoria.Google Scholar
- Van Wyk, A. E. & Smith, G. F. (2001). Regions of floristic endemism in southern Africa. A review with emphasis on succulents. Umdaus Press, Hatfield.Google Scholar