Steirodiscus speciosus

Taxonomy
Scientific Name
Steirodiscus speciosus (Pillans) B.Nord.
Higher Classification
Dicotyledons
Family
ASTERACEAE
Synonyms
Gamolepis speciosa Pillans, Psilothonna speciosa (Pillans) E.Phillips
National Status
Status and Criteria
Critically Endangered B1ab(ii,iii,iv,v)+2ab(ii,iii,iv,v)
Assessment Date
2016/02/03
Assessor(s)
D. Raimondo, N.A. Helme & L. von Staden
Justification
A historically highly range-restricted species that has lost most of its habitat to urban expansion, and remaining habitat is severely degraded due to alien plant infestations and overgrazing. It is currently known from a single, small subpopulation that is not protected. It possibly still occurs in Sand Plain Fynbos near the coast between Darling and Bokbaai, but it has not been recorded in this area for over 30 years.
Distribution
Endemism
South African endemic
Provincial distribution
Western Cape
Range
Darling to Atlantis.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Atlantis Sand Fynbos, Hopefield Sand Fynbos
Description
Sandy flats.
Threats
This species has lost most of its habitat to urban expansion around Atlantis, and urban expansion continues to threaten the only known remaining subpopulation, which occurs on land just outside the urban edge. Remaining habitat is also densely infested with unmanaged alien invasive plants, which are outcompeting native species. Commonages around Mamre and Atlantis are also continually degraded due to overgrazing. It formerly occurred at Kalbaskraal, where it is now locally extinct due to habitat loss to crop cultivation, and degradation due to alien plant invasion and overgrazing. This species could possibly still occur on the coastal flats between Darling and Yzerfontein, but here most of its remaining habitat is also degraded due to alien plant infestations, overgrazing and crop cultivation.
Population

This species is known historically from only a few records from a small area of about 300 km². Most of these records are from the 1970s and earlier. The only two recent records are from a small area between Mamre and Atlantis, where a small subpopulation was seen after a fire. This species apparently only emerges after disturbance such as fire, and is never seen in mature vegetation (Manning et al. 2013), which may explain the rarity of records. Remaining sand plain fynbos in the area is extensively degraded, densely infested with alien invasive plants, and fires are often excluded from small fragments, which means that plants, if still present in the seed bank would seldom emerge. The area is however also exceptionally well-explored for rare and threatened plants, and it is therefore unlikely that it is very common and just overlooked. It could possibly still occur in a small private nature reserve near the coast south-west of Darling, where it was last recorded in 1983.


Population trend
Decreasing
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Steirodiscus speciosus (Pillans) B.Nord.EN B1ab(ii,iii,iv,v)+2ab(ii,iii,iv,v)Raimondo et al. (2009)
Steirodiscus speciosus (Pillans) B.Nord.VU D2Victor (2002)
Steirodiscus speciosus (Pillans) B.Nord.Vulnerable Hilton-Taylor (1996)
Psilothonna speciosa (Pillans) E.PhillipsVulnerable Hall et al. (1980)
Bibliography

Goldblatt, P. and Manning, J.C. 2000. Cape Plants: A conspectus of the Cape Flora of South Africa. Strelitzia 9. National Botanical Institute, Cape Town.


Hall, A.V., De Winter, M., De Winter, B. and Van Oosterhout, S.A.M. 1980. Threatened plants of southern Africa. South African National Scienctific Programmes Report 45. CSIR, Pretoria.


Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical Institute, Pretoria.


Manning, J.C., Goldblatt, P. and Joubert, L. 2013. A taxonomic revision of the small Cape genus Steirodiscus (Asteraceae: Senecioneae). Bothalia 43(1):109-119.


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.


Victor, J.E. 2002. South Africa. In: J.S. Golding (ed), Southern African plant Red Data Lists. Southern African Botanical Diversity Network Report 14 (pp. 93-120), SABONET, Pretoria.


Citation
Raimondo, D., Helme, N.A. & von Staden, L. 2016. Steirodiscus speciosus (Pillans) B.Nord. National Assessment: Red List of South African Plants version 2017.1. Accessed on 2017/03/27

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Distribution map


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