Taxonomy
Scientific Name
Conophytum bilobum (Marloth) N.E.Br. subsp. altum (L.Bolus) S.A.Hammer
Higher Classification
Dicotyledons
Family
AIZOACEAE
Synonyms
Conophytum altum L.Bolus, Conophytum altum L.Bolus var. altum, Conophytum altum L.Bolus var. plenum L.Bolus, Conophytum apertum Tischer, Conophytum connatum L.Bolus, Conophytum corniferum Schick & Tischer, Conophytum durnale N.E.Br., Conophytum gracile N.E.Br., Conophytum gracile N.E.Br. var. gracile, Conophytum gracile N.E.Br. var. majusculum L.Bolus, Conophytum graciliramosum L.Bolus, Conophytum luiseae Schwantes, Conophytum luiseae Schwantes var. papillatum L.Bolus
National Status
Status and Criteria
Vulnerable A4cd
Assessment Date
2021/11/10
Assessor(s)
A.J. Young, P.G. Desmet, 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 2,703 km² and area of occupancy (AOO) of 80 km². This succulent 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 for this particular taxon 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 habitat quality is in decline. This is further supported by observations of habitat degradation as a result of livestock overgrazing. Climate models indicate a loss of 64% of suitable bio-climatic habitat by 2080 under likely CO2 emission scenarios (RCP 2.6). This relatively widespread taxon occurs across several vegetation units and is expected to have a level of resilience to climate change. Thus while model predictions place this species 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 restricted to the winter rainfall area of the Northern Cape province of South Africa.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Succulent Karoo
Description
This taxon is endemic to the Richtersveld bioregion in the Succulent Karoo biome. Plants are often found in partial shade in the shelter of larger shrubs. 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 degradation and loss of 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. Species in this genus have limited dispersal ability and migration to suitable habitats elsewhere is regarded as highly unlikely. 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. 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 species.
Population

No formal estimation of population size exists for this succulent but it is likely to be between 10,000 and 25,000 mature individuals. There is currently a low level of population decline taking place as a result of illegal harvesting for the succulent ornamental trade.


Population trend
Decreasing
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Conophytum bilobum (Marloth) N.E.Br. subsp. altum (L.Bolus) S.A.HammerLeast 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.


Hausfather, Z. and Peters, G.P. 2020. Emissions - the 'business as usual' story is misleading. Nature 577(618-620).


Citation
Young, A.J., Desmet, P.G., 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. altum (L.Bolus) S.A.Hammer. National Assessment: Red List of South African Plants version . Accessed on 2024/12/07

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Distribution map

© A.J. Young

© A.J. Young


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