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Sporisorium elionuri-tristis Vánky

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Scientific name
Sporisorium elionuri-tristis
Author
Vánky
Common names
 
IUCN Specialist Group
Rust and Smut
Kingdom
Fungi
Phylum
Basidiomycota
Class
Ustilaginomycetes
Order
Ustilaginales
Family
Ustilaginaceae
Assessment status
Published
Assessment date
2017-11-10
IUCN Red List Category
CR
IUCN Red List Criteria
B2ab(ii,iii)
Assessors
Denchev, T.T. & Denchev, C.M.
Reviewers
Dahlberg, A.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/73743179/73743188

Justification

Sporisorium elionuri-tristis is a host specific smut fungus which develops sori in the spikelets of Elionurus tristis (Poaceae). The fungus is fully dependent on its host plant for its existence and inevitably more rare than its host plant.

The host plant, E. tristis, is a grass endemic to Madagascar, with distribution restricted to the Central High Plateau, and only recorded at a few sites, in six regions: Alaotra-Mangoro, Analamanga, Itasy, Vakinankaratra, Amoron’i Mania, and Haute Matsiatra. A Red List assessment of this plant has not been undertaken but it warrants being assessed.

Sporisorium elionuri-tristis is known only from the type locality (south of Ambositra, the Central High Plateau, Madagascar) where it was collected in 1964. In the same way as its host plant, S. elionuri-tristis is threatened by habitat loss and degradation. With the help of an aerial photograph-based analysis of randomly sampled sites of the Malagasy Highlands, it was demonstrated that significant parts of the grasslands have been converted to crops fields, farm trees and built-up areas. The typical agricultural system for that region is centred on intensive smallholder production of wet rice and a variety of dry-land crops such as corn, cassava, sweet potatoes, beans, fruit trees, and market vegetables. The majority of the highland landscape has also been heavily modified by long-term history of domesticated grazing and anthropogenic fire regimes.

This is a threatened parasitic fungus on a declining and apparently threatened host plant. Sporisorium elionuri-tristis fulfills B-criterion using area of occupancy (known AOO is only 4 km2, but even if it occurs at more sites it is estimated not to exceed 500 km2) and precautionarily meets the Critically Endangered requirements under criterion B2, regarding subcriteria a (number of locations) and b (ii and iii) (continuing decline – inferred – in the area of occupancy, the area, extent, and quality of the habitat).

Geographic range

Sporisorium elionuri-tristis is known only from the type locality (south of Ambositra, central Madagascar) where it was collected in 1964 (Vánky 2011, Vánky et al. 2011). The host plant, Elionurus tristis, is endemic to Madagascar and has a limited distribution, restricted to the Central High Plateau, and has a fragmented population. The smut fungus is for sure much more rare than its host plant. The known area of occupancy is only 4 km2 and even if it were to be more widespread it is still thought to be < 500 km2 as a maximum.

Population and Trends

There is no specific information on population size or trends. However, the host plant has a fragmented population and limited distribution (restricted to the Central High Plateau of Madagascar) within an area considered to be subject to ongoing and increasing agricultural encroachment.

Population Trend: decreasing


Habitat and Ecology

Sporisorium elionuri-tristis is a smut fungus which develops sori in the spikelets of Elionurus tristis (Poaceae). The fungus is host-specific and depends on its host plant. E. tristis is a perennial, caespitose grass, with erect culms ca 15–60 cm high which grows in grasslands.

Threats

Sporisorium elionuri-tristis is threatened by habitat loss and degradation of its host plant. With the help of an aerial photograph-based analysis of randomly sampled sites of the Malagasy Highlands, it was demonstrated that a significant part of the grasslands has been converted to crops fields, farm trees and built-up areas (Kull 2012). The typical agricultural system for that region is centred on intensive smallholder production of wet rice and a variety of dry-land crops such as corn, cassava, sweet potatoes, beans, fruit trees, and market vegetables (Kull 1998, 2008). The majority of the highland landscape has also been heavily modified by long-term history of domesticated grazing and anthropogenic fire regimes (Kull 2012).


Conservation Actions

The only known site of this smut fungus is not in a protected area. Assessment and conservation of the host plant is needed. Ex situ conservation of the plant will not necessarily protect the fungus: in situ conservation is needed.

Source and Citation

Denchev, T.T. & Denchev, C.M. 2022. Sporisorium elionuri-tristis. The IUCN Red List of Threatened Species 2022: e.T73743179A73743188. https://dx.doi.org/10.2305/IUCN.UK.2022-2.RLTS.T73743179A73743188.en .Accessed on 21 December 2023

Country occurrence