Attention: Order and family should be Boletaceae, Boletales
EOO is large enough for LC, but AOO is 120 Km2, which together with decline in area of habitat is enough for EN B2b(iii). However, given that I’m assuming a multiplier for unknown locations I am not sure if this criterion should be applied.
Estimates for habitat decline (18% in 20yrs) were taken from GFW using polygons in the map for this assessment. I have drawn small polygons, because the region seems to have been well sampled, but if I assume larger areas of distribution in New South Wales, the habitat decline would surpass thresholds for EN.
GBIF includes record from China, but this is an error – I checked original article and the voucher was collected in Australia.
Gymnogaster boletoides is an Australian species, likely endemic, known mostly from the east and south-eastern coasts. Its population size is estimated at 2700 mature individuals and is expected to be in decline due to habitat loss (45% in 3 generations). Therefore, G. boletoides applies for the Vulnerable (VU) category, through criterion A2c+3c+4c and C1.
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). G. boletoides has no synonyms.
Only known from Australia, where fruitbodies have been observed in southern Queensland, New South Wales, Victoria and in a single location in Western Australia. G. 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.
Known from approximately 27 sites (GBIF.org, 2023; Gellardi et al. 2017). 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 around 2700 mature individuals, following guidelines by Dahlberg and Mueller (2011), assuming 10 mature individuals exist per site and applying a 10x multiplier for unknown sites.
Population size is expected to be in decline due to habitat loss. Global Forest Watch shows a decrease in tree cover (>30% canopy density) of 18% for the assumed area of distribution for this species (polygons drawn for the distribution of this species in this assessment), corresponding to a decline in 45% in 50 years (3 generation period for mycorrhizal species).
Population Trend: Decreasing
G. 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. (Gellardi et al. 2017). It is likely ectomycorrhizal, but no host relationships have been confirmed (Tedersoo and Smith, 2013).
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. 2018), 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).
Habitat protection and management, namely of fire frequency and level of disturbance, are needed to prevent further declines in population for this G. boletoides.
Search efforts in less sampled areas is 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.
There are no known uses for this species.