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Scientific Name | Conophytum bilobum (Marloth) N.E.Br. subsp. bilobum |
Higher Classification | Dicotyledons |
Family | AIZOACEAE |
National Status |
Status and Criteria | Vulnerable A4cd |
Assessment Date | 2021/11/09 |
Assessor(s) | A.J. Young, I. Ebrahim, D. Guo, A. Harrower, L. Jabar, L. Knoetze, C. Rodgerson, P.C.V. Van Wyk & N.N. Mhlongo |
Justification | This succulent is endemic to the Northern Cape province of South Africa with an extent of occurrence (EOO) of 20,924 km² and area of occupancy (AOO) of 972 km². This taxon has been subject to illegal collection of mature individuals for the international trade in ornamental succulents in 2020-21. The continued threat of illegal collection is therefore regarded as high but the scattered distribution of mature individuals across its range may limit the impact. A decline of up to 25% is likely within the next three generations (90 years).
Anthropogenic climate change is another major threat to this succulent in the future. Loss of vegetation cover has been observed across the range occupied by this taxon via Landsat imagery between 1984 and 2018 and is used to infer that the habitat quality is already in decline. Climate models for this taxon indicate a loss of 64% of suitable bio-climatic habitat by 2080 under likely CO2 emission scenarios (RCP 2.6). This relatively widespread succulent occurs across several vegetation units and is expected to have a level of resilience to climate change. Thus while model predictions place this taxon in the category Endangered under criterion A4, we have decreased the expected population reduction by 20% to 44% based on the uncertainty of the response given the expected resilience of this species. It therefore qualifies as Vulnerable under criterion A4. |
Distribution |
Endemism | South African endemic |
Provincial distribution | Northern Cape |
Range | This taxon is endemic to the Northern Cape province of South Africa. |
Habitat and Ecology |
Major system | Terrestrial |
Major habitats | Succulent Karoo |
Description | This succulent is primarily associated with the Succulent Karoo biome but is also found in the Nama-Karoo and Desert biomes. It is very widespread across several bioregions and vegetation units. The plants occupy a wide range of niches including sun-exposed quartz fields, in partial shade under shrubs or rocks and on gneiss hilltops amongst broken rocks. This taxon has a generation length of 30 years. It is expected to be sensitive to the impacts of climate change as it does not disperse and while adapted to arid conditions, is dependent on limited seasonal rainfall. Species in the genus are sensitive to long periods of drought. Drought related mortality has been observed for other closely related taxa within the genus. |
Threats |
| Plants have been subject to illegal collection of mature individuals for the international trade in ornamental succulents in 2020-21. This taxon has been highly sought after by collectors and is highly likely to remain so in future. Another threat includes nomadic livestock grazing which is causing ongoing loss and degradation of its habitat.
Anthropogenic climate change is a long-term threat to this succulent. Climate models for the likely emission scenarios where emissions stay at present day levels (RCP 2.6) (Hausfather and Peters 2020) and worst case scenarios where emissions continue to increase during the 21st century (RCP 8.5) indicate that there will be a loss of suitable bioclimatic envelope of between 64% and 99% by 2080 for the species with the assumption that all subspecies will be similarly impacted. However, as this taxon occurs across several vegetation units it is expected to have a level of resilience to climate change and the expected population loss is reduced by 20% to 44% based on the uncertainty of the response given the expected resilience of this taxon. Taxa in this genus have limited dispersal ability and migration to suitable habitats elsewhere is regarded as highly unlikely.
Loss of vegetation cover as inferred from changes in Enhanced Vegetation Index (EVI) between 1984 and 2018 using Landsat data (Venter et al. 2020) has been experienced across the geographic range for this taxon. |
Population |
No formal estimation of population size exists for this succulent but it is likely to be well in excess of 200,000 mature individuals. There is currently a low level of population decline taking place as a result of illegal harvesting for the succulent ornamental trade.
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Population trend | Decreasing |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | | Conophytum bilobum (Marloth) N.E.Br. subsp. bilobum var. bilobum | Least Concern | Raimondo et al. (2009) | | Conophytum bilobum (Marloth) N.E.Br. subsp. bilobum var. elishae (N.E.Br.) S.A.Hammer | Least Concern | Raimondo et al. (2009) | | Conophytum bilobum (Marloth) N.E.Br. subsp. bilobum var. linearilucidum (L.Bolus) S.A.Hammer | Least Concern | Raimondo et al. (2009) | | Conophytum bilobum (Marloth) N.E.Br. subsp. bilobum var. muscosipapillatum (Lavis) S.A.Hammer | Least Concern | Raimondo et al. (2009) | |
Bibliography |
Hammer, S. 2002. Dumpling and his wife: New view of the genus Conophytum. EAE Creative Colour, Norwich.
Hammer, S.A. 1993. The genus Conophytum: A conograph. Succulent Plant Publications, Pretoria.
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Citation |
| Young, A.J., Ebrahim, I., Guo, D., Harrower, A., Jabar, L., Knoetze, L., Rodgerson, C., Van Wyk, P.C.V. & Mhlongo, N.N. 2021. Conophytum bilobum (Marloth) N.E.Br. subsp. bilobum. National Assessment: Red List of South African Plants version . Accessed on 2024/12/07 |
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