Assessment Notes

Justification

Heteroradulum brasiliense is a saprotrophic species found on dead wood in well preserved colder forests of southern Brazil, including submontane, montane and cloud forests in Araucaria forests and coastal Atlantic forests. It is likely restricted to the subtropical/temperate Atlantic Forest formations in southern Brazil. It is likely to be a very rare species, due to the few records despite the history of intensive sampling in its area of occurrence. The total population is conservatively estimated at 2,500 to 5,000 mature individuals, distributed in up to 500 sites in southern Brazil, each with an average of up to 10 mature individuals. The species occurs in fragmented, historically affected forests that have lost 97% of their original cover in 100 years, a decline that remains ongoing today. An extensive amount of this loss took place over the last 50 years, due to land conversion for farming and plantations as well as logging activities. Ongoing threats include the loss of its habitat from the impacts of climate change, as well other anthropogenic factors, including deforestation and introduction of invasive species. An additional suspected population loss of 20-25% is expected to occur over the next 20 years due to continued loss of appropriate habitat. In lower elevation areas this loss of habitat is mainly due urban and agricultural expansion, while in montane areas it is mainly due to deforestation, impacts of introduced species (mainly cattle), and impacts of climate change. This species is assessed as Vulnerable - C2a(ii).

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Geographic range

Heteroradulum brasiliense is known only from subtropical/temperate forests of southern Brazil (Lowy 1971, Malysheva and Spirin 2017, Kossmann 2022). It is probably restricted to subtropical/temperate Atlantic Forest formations (Araucaria forests, coastal forests, cloud forests) in southern Brazil.

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Population and Trends

Heteroradulum brasiliense is a very rare species, known from only two records in southern Brazil, despite the history of intensive sampling in its area of occurrence (Kossmann 2022). The total population, comprising a single subpopulation, is conservatively estimated to be between 2,500 to 5,000 mature individuals, distributed in up to 500 sites in southern Brazil, each site with an average no more than 10 mature individuals.

A population loss of 20-25% is suspected for the next 20 years (three generation lengths) due to loss of appropriate habitat in lower elevation areas mainly due to habitat loss for urban and agricultural expansion, and in montane areas mainly due to deforestation, impacts of introduced species (mainly cattle), and impacts of climate change (Brooks and Balmford 1996, Pinto et al. 2006, Mulligan 2011, Carlucci et al. 2016, Castro et al. 2020).

Population Trend: Decreasing

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Habitat and Ecology

The species is saprotrophic on dead wood. It is found in well preserved colder forests of southern Brazil, including submontane, montane, and cloud forests in Araucaria forests and coastal Atlantic forests.

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Threats

The species occurs in fragmented, historically affected forests that have lost 97% of their original cover over the past 100 years, a decline that remains ongoing today. An extensive amount of this loss took place in the last 50 years, due to land conversion for urbanisation, farming and plantations as well as logging activities. Ongoing threats include the loss of its habitat from the impacts of climate change, as well other anthropogenic factors, such as fire, deforestation and introduction of invasive species (Brooks and Balmford 1996, Pinto et al. 2006, Mulligan 2011, Carlucci et al. 2016, Castro et al. 2020).

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Conservation Actions

Conservation of Heteroradulum brasiliense will involve the preservation of its habitat in conservation areas and the effective enforcement of conservation policies. More surveys, aimed at finding the species are needed in its region of appropriate habitat to document its population size and distribution. Additionally, systematic studies with molecular phylogenetic data can help understand the evolutionary history and relationships of the species, but no sequences are available online, so far.

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Source and Citation

Kossmann, T., Zabin, D., Menolli Jr, N. & de Andrade Borges, M. 2024. Heteroradulum brasiliense. The IUCN Red List of Threatened Species 2024: e.T265909377A265910511. Accessed on 26 November 2025.

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• Country occurrence