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Scientific Name | Crassothonna opima (Merxm.) B.Nord. |
Higher Classification | Dicotyledons |
Family | ASTERACEAE |
Synonyms | Othonna opima Merxm. |
National Status |
Status and Criteria | Critically Endangered A2acd |
Assessment Date | 2022/08/19 |
Assessor(s) | D. Raimondo, P.C.V. Van Wyk, N.A. Helme & N.N. Mhlongo |
Justification | This species has a limited distribution range within South Africa. The population has undergone a reduction of at least 95% due to the combined effects of mining and the ongoing droughts in the Northern Cape, which commenced in 2016 and persist at the time of this assessment. Although the species also occurs in the Sperrgebiet region of southern Namibia, the impacts of the drought have been equally severe. As a result, its national status is not downgraded, and it qualifies as Critically Endangered under criterion A. |
Distribution |
Endemism | Not endemic to South Africa |
Provincial distribution | Northern Cape |
Range | This species distribution stretches from the Richtersveld in the Northern Cape Province of South Africa into southern Namibia. |
Habitat and Ecology |
Major system | Terrestrial |
Major habitats | Upper Annisvlakte Succulent Shrubland, Central Richtersveld Mountain Shrubland, Western Gariep Hills Desert, Western Gariep Lowland Desert, Kahams Mountain Desert, Noms Mountain Desert, Lower Gariep Alluvial Vegetation |
Description | Plants grow on rocky slopes. |
Threats |
| Anthropogenic climate change poses a long-term threat to this species. Since 2012, its entire range has experienced below-average rainfall. Predictions for future climate change indicate further increases in the annual average temperature, ranging between 1.4°C and 2.4°C by 2050. This will lead to unbearably hot temperatures and ongoing aridification throughout significant portions of the year (Van Wilgen et al., 2017).
The species has suffered severely from a drought that began in 2016 and is still ongoing at the time of this assessment. Approximately 95% of this once common species is now dead and severely fragmented. Like other Crassothonnas in the region, they lack long-lived seedbanks, and plants have not flowered in many years. Once a subpopulation is lost, it is lost forever.
In addition to the impacts of climate change, the species has already lost habitat to mining, and this loss will persist as mining operations expand their footprints. Mining has also resulted in the death of thousands of plants, and much more of the habitat will be lost in the coming years. |
Population |
The population consists of between 20-30 subpopulations across its range and between 10-15 locations within South Africa. A distinct difference exists between the northern Richtersveld and Sperrgebiet population and the southern Richtersveld populations, which are geographically divided. Whether this represents two variable subspecies or two entirely different species is a matter that requires further taxonomic assessment. Despite this distinction, the entire population has suffered a 95% decline due to the combined effects of the ongoing drought and mining activities.
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Population trend | Decreasing |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | | Crassothonna opima (Merxm.) B.Nord. | Least Concern | 2015.1 | | Othonna opima Merxm. | Least Concern | Raimondo et al. (2009) | |
Bibliography |
Nordenstam, B. 2012. Crassothonna B.Nord., a new African genus of succulent Compositae-Senecioneae. Compositae Newsletter 50:70-77.
Raimondo, D., von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. and Manyama, P.A. 2009. Red List of South African Plants. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
Van Wilgen, N.J. and Herbst, M. 2017. Taking stock of parks in a changing world: The SANParks Global Environmental Change Assessment. SANParks, Cape Town.
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Citation |
| Raimondo, D., Van Wyk, P.C.V., Helme, N.A. & Mhlongo, N.N. 2022. Crassothonna opima (Merxm.) B.Nord. National Assessment: Red List of South African Plants version . Accessed on 2024/12/06 |
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