Assessment Notes

Justification

Gymnogaster boletoides is an Australian species, likely endemic, known mostly from the east and south-eastern coasts. Its population size is estimated at 2,700 mature individuals (with the majority in the subpopulation in Queensland/New South Wales) and is inferred to be in decline due to habitat loss and associated tree hosts as a result of changes in fire frequency and intensity. Although the rate of past population declines are difficult to estimate, recent rates of habitat loss and ongoing threats can be used to suspect a current and future population decline of 45% in three generations (50 years). Therefore, G. boletoides is assessed as Vulnerable (VU) A3c+4c.

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Taxonomic notes

This is the type and only species in the monotypic genus Gymnogaster, established based on its morphological characteristics and later confirmed through a phylogenetic study (Halling et al. 2012).

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Geographic range

This species is only known from Australia where sporocarps have been observed in southern Queensland, New South Wales, Victoria and in a single location in Western Australia. Gymnogaster boletoides’ DNA has also been found in soil samples from South Australia and Northern Territory (GBIF.org 2023) which is suggestive of a possible wider distribution within Australia, but the known habitat for this species (wet sclerophyll forests) does not occur in these states (Peeters and Butler 2014) and no sporocarps have so far been recorded.

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Population and Trends

Gymnogaster boletoides is known from approximately 27 sites (Gellardi et al. 2017, GBIF.org 2023). Several collections were made between 2005 and 2015 when intensive mycological field research was done in eastern and south-eastern Australia where this species is mostly found. For this reason, the total number of sites is not expected to be much larger and population size is estimated to be around 2,700 mature individuals following guidelines by Dahlberg and Mueller (2011), assuming 10 mature individuals exist per site and applying a 10 x multiplier for unknown sites. Most records are found in the subpopulation in southern Queensland to northern New South Wales.

The population size is inferred to be in decline due to habitat loss with associated lost of obligate host trees. Global Forest Watch shows a decrease in tree cover (30% canopy density) of 18% for the assumed area of distribution for this species between 2001 and 2021 (see map), with the most significant decreases in recent years (13% between 2019 and 2021). Assuming a constant decrease in habitat per year, and that this would directly translate to population declines, an ongoing and future population decline of 45% in 50 years is suspected (three generation period for ectomycorrhizal species). Given the available data and that habitat loss due to fire and other stressors is higher now than in the past it is difficult to estimate the rate of past population decline of the species.

Population Trend: Decreasing

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Habitat and Ecology

Gymnogaster boletoides is a secotioid, epigeous species, with gregarious or scattered fruitbodies, found among litter in wet sclerophyll forests with Eucalyptus sp., Lophostemon sp. and Corymbia sp. (Gelardi et al. 2017). It is likely ectomycorrhizal, but no host relationships have been confirmed (Tedersoo and Smith 2013).

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Threats

This species is threatened by a decrease in quality and area of habitat, namely through changes in fire frequency, grazing pressures and increased tree mortality caused by the bell miner-associated dieback (caused by sap-feeding insects) (Peeters and Butler 2014). Fire is part of the natural regeneration dynamics of wet sclerophyll forests, but changes in its frequency can interfere with the viability of this type of forest. That is, a decrease in fire frequency and low levels of disturbance can lead to the evolution to a rainforest habitat (Krishnan et al. 2019), while an increase frequency caused by climate change and drier conditions can prevent seed deposition and regeneration, possibly leading to its transformation into Acacia sp. dominated forests (Cawson et al. 2018).

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Conservation Actions

Habitat protection and management, namely of fire frequency and level of disturbance, are needed to prevent further declines in population of Gymnogaster boletoides. Search efforts in less sampled areas are recommended to improve estimates of population size, specifically in Western Australia where only one site has been identified. More research into host preference is also needed to help establish threats.

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Use and Trade

There are no known uses for this species.

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Source and Citation

Cunha, S.P. & Gonçalves, S.C. 2024. Gymnogaster boletoides. The IUCN Red List of Threatened Species 2024: e.T258432971A258434799. Accessed on 22 November 2025.

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• Country occurrence