Assessment Notes

Justification

Nigroboletus roseonigrescens is a bolete known from south-eastern China. The species was described in 2015 from two sites in Guangdong Province, but it is thought to be common and a wider distribution is likely. For this reason, the population size is estimated to be of at least 20,000 mature individuals. Since no specific plant host relationship or significant population decline has been established, the species is assessed as Least Concern (LC).

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Taxonomic notes

Nigroboletus roseonigrescens is the only species of the Nigroboletus genus (Gellardi et al. 2015).

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Geographic range

So far this species is known from two localities in Guangzhou, Guangdong Province, China.

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Population and Trends

This species has so far only been reported from two distinct localities in Guangzhou, between 2012 and 2014. However, Gellardi et al. (2015) noted that the species appears to be common and abundant and admit the possibility of a larger area of distribution in south-eastern Asia. Therefore, considering that this is a terrestrial fungus, and the guidelines by Dahlberg and Mueller (2011), the population size is estimated at 20,000 mature individuals (2 known sites x 10 mature individuals x 1,000 multiplier for potential additional sites).

The southeastern and south regions of China, where the Guangzhou region is located, present the higher deforestation rates in China (Zhang et al. 2022), and World Resources Institute (2022) shows a decrease in forest cover (30% canopy density) of 20% between 2001 and 2021 in the Guangdong province. Surrounding provinces also show some degree of deforestation for this period: 20% in Guangxi, 7% in Hunan, 12% in Jiangxi and 14% in in Fujian. Still, forests dominated by Castanopsis fissa or Castanea henryi were not included in Red list of China’s forest ecosystems (Chen et al. 2020) and the existence of other potential hosts make estimating population declines through habitat reduction difficult.

Population Trend: Unknown

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Habitat and Ecology

Nigroboletus roseonigrescens grows in clayey soil among litter, gregariously or scattered. It was found in tropical montane and lowland mixed forests with mostly Castanopsis fissa, Castanea henryi, Lithocarpus sp., as well as Schima superba and Litsea rotundifolia var. oblongifolia (Gelardi et al. 2015)

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Threats

Deforestation for agriculture and development in southern China can present a threat to this species.

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Conservation Actions

Given that deforestation may present a threat to this species, monitoring and protection of areas of potential habitat in the south of China is recommended to prevent declines in the population. Increased search efforts in other regions are needed to confirm whether this species has a wider distribution and to obtain a better estimate of the population size. More research into its habitat specificity would also be important to establish potential threats.

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Source and Citation

Cunha, S.P. & Gonçalves, S.C. 2025. Nigroboletus roseonigrescens. The IUCN Red List of Threatened Species 2025: e.T273603316A273891160. Accessed on 22 November 2025.

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• Country occurrence