Taxonomy
Scientific Name
Disa newdigateae L.Bolus
Higher Classification
Monocotyledons
Family
ORCHIDACEAE
Synonyms
Herschelia newdigateae (L.Bolus) H.P.Linder, Herschelianthe newdigateae (L.Bolus) N.C.Anthony
National Status
Status and Criteria
Critically Endangered B1ab(iii)+2ab(iii); C2a(i); D
Assessment Date
2023/11/23
Assessor(s)
D. Raimondo & L. Muller
Justification
Previously thought to be possibly extinct, this extremely rare orchid, endemic to the Garden Route region of South Africa, was rediscovered in 2018 after not being recorded since 1935. As of November 2023, only six plants are known from one location. The species has an extent of occurrence (EOO) and area of occupancy (AOO) of 4 km². The population is inferred to be declining due to habitat degradation caused by invasive alien plant species. Therefore, it qualifies for listing as Critically Endangered under criteria B, C, and D.
Distribution
Endemism
South African endemic
Provincial distribution
Western Cape
Range
This species occurs in the Garden Route region of the Western Cape Province South Africa.
Habitat and Ecology
Major system
Terrestrial
Major habitats
South Outeniqua Sandstone Fynbos
Description
It grows on stony slopes near the coast, in short fynbos.
Threats
The majority of this species' former habitat has been lost to timber plantations, or has been degraded by dense infestations of invasive alien plants. There is ongoing habitat degradation as a result of invasive alien plants at the only known extant location.
Population

Known historically from one subpopulation near the Crags, Plettenberg Bay, where six plants were collected between 1895 and 1931. It was not seen again until 2018 when a small subpopulation was discovered some distance away from the historical collections. Surveys conducted by members of the Custodians of Rare and Endangered Wildflowers' Outramps group recorded two stands of three plants within an area of 300 m by 70 m in the year 2022. Since this is an incredibly cryptic plant and the habitat had not burnt, it is possible that more plants may exist. However, considering that orchids often occur in low numbers and that this orchid has been regularly searched for by specialists over the past 90 years, yielding only these six plants, no more than 50 mature individuals are suspected to be extant. Given ongoing habitat degradation, the population is inferred to be declining at a slow rate.


Population trend
Decreasing
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Disa newdigateae L.BolusCritically Endangered (Possibly Extinct) Raimondo et al. (2009)
Disa newdigateae L.BolusVU D2Victor (2002)
Herschelianthe newdigateae (L.Bolus) N.C.AnthonyVulnerable Hilton-Taylor (1996)
Bibliography

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


Liltved, W.R. and Johnson, S.D. Unpublished. The Cape Orchids - Wild orchids of the Cape Floral Kingdom.


Linder, H.P. 1981. Taxonomic studies in the Disinae. VI. A revision of the genus Herschelia. Bothalia 13(3 & 4):365 - 388.


Linder, H.P. 1999. Disa. In: H.P. Linder and H. Kurzweil (eds.), Orchids of southern Africa (pp. 187-288), A.A. Balkema, Rotterdam.


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. & Muller, L. 2023. Disa newdigateae L.Bolus. National Assessment: Red List of South African Plants version . Accessed on 2024/07/18

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Distribution map


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