Assessment Notes

Justification

Stropharia araucariae is a mushroom-forming species restricted to Araucaria moist forests of southern Brazil and likely northern Argentina. It is currently known only from the type locality and is likely to be a rare species as there are few records even in well surveyed areas in its potential range. Only three specimens have been found in the over 10 years since its description. The species' total population is estimated at no more than 10,000 mature individuals distributed in 200-250 sites, but all in one subpopulation. South American Auricaria moist forests are a fragile habitat that is estimated to have already declined approximately 97% and are projected to decline further in the future. This species is assessed as vulnerable due to its small population size that is threatened by loss of habitat resulting in likely further population decline.

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Geographic range

The species is currently known from São Francisco de Paula National Forest, in Rio Grande do Sul state, southern Brazil. The species occurs in the Atlantic Forest domain, in the Araucaria moist forests. 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 araucariae is currently known only from the type locality. It is likely to be a rare species as there are few records even in well surveyed areas in its potential range, and only 3 specimens have been found in the over 10 years since its description. The species' total population size is estimated at no more than 10,000 mature individuals distributed in 200-250 sites, each with up to 40 mature individuals. Araucaria moist forests, where the species are found, have declined by approximately 97%, with the remaining patches heavily fragmented. Over 80% of the remaining fragments show signs of disturbance, are less than 50 ha in size, and are surrounded by agricultural lands which have been shown to hold a smaller diversity than larger forests (Ribeiro et al. 2009, Souza et al. 2012, Nodari 2016). Between 2001 and 2018, the habitat had a loss in cover of approximately 3.1% (13% loss and 9.9% gain) (World Resources Institute 2020). Additionally, in chronically disturbed areas, Araucaria moist forests are kept at early successional stages, which may not hold the appropriate conditions to support species from pristine fungal communities such as S. araucariae. 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 araucariae is a saprotrophic mushroom found on soil litter among grasses and fallen leaves in South American Araucaria moist forests.

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Threats

The species is threatened by habitat loss, mainly due to logging, fire, and conversion of forests into agricultural lands. Araucaria moist forests have lost approximately 97% of their original extent, with 80% of the remaining area being composed of disturbed fragments under 50 ha in size located inside 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 forest range. Araucaria moist forests are restricted to higher altitudes with subtropical climates, high year-long precipitation, cold winters and temperate summers. Studies have shown that by 2070, Araucaria angustifolia, the dominant tree of the AMF, will likely be restricted to highland microrefugia as an impact of climate change. This suggests that the structure of the AMF will be drastically different, or that the AMF itself will also be restricted to these microrefugia.

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Conservation Actions

The main actions 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. There are no DNA sequences available for the species, and no phylogenetic studies have been conducted to test its phylogenetic position. Additionally, herbaria revisions from specimens identified as Stropharia rugosoannulata from AMF may represent new records from S. araucariae, as the species are reported by the authors to be morphologically similar.

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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., Santos, P. & Drechsler-Santos, E. 2021. Stropharia araucariae. The IUCN Red List of Threatened Species 2021: e.T196136102A196845928. https://dx.doi.org/10.2305/IUCN.UK.2021-1.RLTS.T196136102A196845928.en .Accessed on 3 April 2024

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• Country occurrence