Assessment Notes

Justification

Stropharia acanthocystis is a mushroom-forming species from the Araucaria moist forests of southern Brazil, a very fragile habitat that is estimated to have declined by approximately 97% and is projected to further decline in the future. The total population of the species is estimated at no more than 10,000 mature individuals in one subpopulation, distributed in an estimated 250 sites. It is assessed as Vulnerable.

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Geographic range

The species is currently known from São Francisco de Paula National Forest, in Rio Grande do Sul state, and Rio do Peixe City Park in Joaçaba, Santa Catarina state, both in the Araucaria moist forests of the Atlantic Forest domain of southern Brazil. It is expected to be found throughout the Araucaria moist forests in southern Brazil and a small part of northern Misiones, Argentina.

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Population and Trends

Stropharia acanthocystis is currently known only from two sites in Araucaria moist forests. Although it is conspicuous, there are few records even in well surveyed areas of its potential range, with only 10 specimens being found in the over 10 years since its description. It is likely to be a rare species. The habitat where the species is found has declined by about 97%, with the remaining areas heavily fragmented. Over 80% of the remaining fragments are less than 50 ha, and surrounded by agricultural lands. These small fragmented patches have been shown to hold a smaller diversity than larger forests, and show signs of disturbance (Ribeiro et al. 2009, Souza et al. 2012, Nodari 2016). The total population is estimated at no more than 10,000 mature individuals, distributed in an estimated 250 sites, each with up to 40 mature individuals. Between 2001 and 2018, there has been a loss of approximately 3.1% cover (13% loss and 9.9% gain) (World Resources Institute 2020). Additionally, Araucaria moist forests in chronically disturbed areas are kept at early successional stages, which may not hold the appropriate conditions to support species from pristine fungal communities, such as S. acanthocystis. Despite this, though, it is thought that the species could be said to be in one subpopulation.

Population Trend: decreasing

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Habitat and Ecology

Stropharia acanthocystis is a saprotrophic mushroom found on dead angiosperm wood, and less frequently on soil, in Araucaria moist forests of southern Brazil and possibly northern Argentina.

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Threats

This species is threatened by habitat loss, mainly due to logging, fire and conversion of forests into agricultural lands. Araucaria moist forests have lost about 97% of their original extent, with 80% of the remaining area largely disturbed being composed by fragments under 50 ha inside of private farms and surrounded by crop fields and grasslands. Only 3.1% of the remaining habitat is in protected areas, which corresponds to 0.09% of the original Araucaria moist forests' range. Araucaria moist forests are restricted to higher altitudes with subtropical climates with high year-long precipitation, cold winters and temperate summers. Studies have shown that by 2070, Araucaria angustifolia, the dominant tree of the AMF, is assessed as Critically Endangered (Thomas 2013), and will likely be restricted to highland microrefugia as an impact of climate change. This means that the structure of the AMF can be drastically different, or that the AMF itself will also be restricted to these areas.

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Conservation Actions

The main actions required to preserve the species are the protection of its habitat, restoration of Araucaria moist forests, and creation of new conservation areas to harbour the probable microhabitats to which the AMF may be restricted in the future. Also, measures must be taken to assure that the protected AMF areas reach a mature state. More surveys are needed in other areas to confirm the species range, including its association with mature forest conditions. Also, there are no DNA sequences available for the species, and no phylogenetic studies have been conducted to test its phylogenetic position.

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Use and Trade

No use/trade is known.

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Source and Citation

Kossmann, T., Martins da Cunha, K., Seger, C. & Drechsler-Santos, E. 2021. Stropharia acanthocystis. The IUCN Red List of Threatened Species 2021: e.T196136052A196846170. https://dx.doi.org/10.2305/IUCN.UK.2021-1.RLTS.T196136052A196846170.en .Accessed on 9 April 2024

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