Assessment Notes

Justification

Russula galbana is a rarely reported ectomycorrhizal fungus associated with Eucalyptus, and possibly with Allocasuarina species, endemic to north east Australia. Only three sites are known, and there is only a single record in the last 20 years even with relatively intense survey work in the area. This is not an easy fungus to find, occurring in Eucalyptus dominated forests where there is often deep litter from stripped bark on the ground so we may anticipate that there may be a number of undiscovered sites for this species. However, the northern sites where it has been found are in areas that have been relatively well surveyed by mycologists including the Mycoblitz survey in North Queensland and truffle searches in both localities. Because of the difficulty to detect this species, it is estimated that it occurs at 100 or more sites, each with 1-2 mycelia (functional individuals). The number of mature individuals is estimated as ranging between 2500-5000, divided into two subpopulations, each consisting of between 1200 and 3000 individuals. The population is under continuing decline due to disturbance by invasive mammals and bush fires. 

It is therefore assessed as Near Threatened, as it meets the population threshold for Vulnerable C and is undergoing continuing decline, but it is not possible to estimate the rate of population decline (to assess under C1) and the subpopulation structure does not meet the requirements for Vulnerable under C2.

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Geographic range

Russula galbana is Australian endemic only known from Queensland distributed in two widely separated sub-populations, one in North Queensland on the Atherton Tablelands and the other at Bellthorpe in the Blackall Ranges of the Sunshine Coast hinterland. These two areas are over 1500 km apart. Some of the intervening area along the Great Dividing Range might have suitable habitat for this fungus, but based on current best information, it is accepted that there are two subpopulations that do not exchange genetic material. It is found in wet sclerophyll forest with Eucalyptus tereticornis and Eucalyptus grandis. The small secotoid fruit body with a pale yellow brown or pale olivaceous cap and a firm white stem makes this a recognisable but somewhat difficult species to detect.

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Population and Trends

Only three sites are known and there is only a single record in the last 20 years even with relatively intense survey work in the area. This is not an easy fungus to find, occurring in Eucalyptus dominated forests where there is often deep litter from stripped bark on the ground so we may anticipate that there may be a number of undiscovered sites for this species. However, the northern sites where it has been found are in areas that have been relatively well surveyed by mycologists including the Mycoblitz survey in North Queensland and truffle searches in both localities. Taking these factors in to account we think it reasonable to assume that there are likely to be at least 100 sites yet to be discovered.

The ecosystem in which this species is found is relatively intact in the northern locality with 90% of its presettlement extent still present, although the quality of the habitat has undoubtedly declined due to logging, grazing and fire. The southern locality has experienced a greater loss of habitat and less than 50% of the pre-settlement level survives. The population is under continuing decline due to disturbance by invasive mammals and bush fires.

Population Trend: decreasing

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Habitat and Ecology

This species of Russula has only ever been found in wet sclerophyll forests where it is likely to be mycorrhizal with Eucalyptus and/or possibly with Allocasuarina species. In its southern locality it occurs in tall Eucalyptus forest (12.12.15a) dominated by mature E. grandis. The northern sites are in drier forest (9.5.9a) with Corymbia clarksoniana.

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Threats

The habitat in which this species is located is only partially protected for the site in the Dinden Forest Reserve. The other two sites are not formally protected. Grazing by both feral and introduced farm animals occurs at all the sites. Fire is used as a management tool for the northern forests and its effect on these mycorrhizal fungi is not well understood. The two known localities in north Queensland are both surrounded by plantation forestry and grazing lands and are subject to a regular burning regime at 2 – 15 year intervals. The locality in the Sunshine coast hinterland is on privately owned land where the current owner favours conservation. 

Both subpopulations face risks from possibly inappropriate fire regimes. The northern sites are periodically burnt and this is known to reduce the presence of mycorrhizal fungi. Robinson (2007) shows a twelve fold reduction of Russulales in burnt areas when compared to un-burnt sites.

There is also some grazing pressure from exotic species. Cattle grazing has been allowed at both the northern localities in the past, wild pigs are also present. Deer and wild pigs are present in the southern locality. Whilst the precise effects that these activities have on the fungal component of the ecosystem is unknown, circumstantial evidence suggest that forests grazed by exotic animal species have a lower fungal diversity than natural forests in Australia.

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Conservation Actions

This species is not protected, and there is no management plan. This fungus is listed as ‘Least Concern’ by the Queensland Government although they have not carried out any formal assessment.

Research on the biology of this species, and mycorrhizal fungi in general, is needed to formulate effective management plans.

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Use and Trade

The species is not utilized.

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Source and Citation

Leonard, P.L. 2021. Russula galbana. The IUCN Red List of Threatened Species 2021: e.T154531597A209680641. https://dx.doi.org/10.2305/IUCN.UK.2021-3.RLTS.T154531597A209680641.en .Accessed on 2 February 2024

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• Country occurrence