Assessment Notes

Justification

Diacanthodes cerebriporoides grows in the ground of the Piedmont Forest, probably associated with roots, causing white rot. Despite it not be able to assume an association to a specific host the fungal species is considered endemic to the Piedmont Forests of the southern Yungas in Argentina and potentially Bolivia too. Also, despite being a large-sized species, it is considered rare, since only seven collections from five localities have been made in the last 70 years (1949-2022). Since only 10% of the original area of the Piedmont Forest is currently preserved (Malizia et al. 2012), we approximated that there could be around 100-150 sites in Argentina and Bolivia where the required conditions for this species exist. Therefore, it is inferred that currently there is a population consisting of between 1,000 and 3,000 mature individuals in one subpopulation. This overlaps the Vulnerable-Endangered threshold under criterion C, but here a conservative judgement is made that it may be towards the upper end of the population size estimate. The three generation time period of this species is 30 years, and it is predicted that, mainly due to climate change, the suitable area for the specific forest which harbours this species population is in continuing decline and will suffer a reduction at least of 15% in the next 30 years (year 2050) (Pacheco et al. 2010). Therefore, considering the threats to the species, especially the small area of its natural environment remaining which is seriously affected by anthropogenic disturbance and climate change, D. cerebriporoides is assessed as Vulnerable under criterion C2a(ii). Further research is needed, though, and if the population size is found to be towards the lower end of the estimate (or even lower) then a higher threat category would be warranted.

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Geographic range

Diacanthodes cerebriporoides is an endemic species of the Piedmont Forests of the southern Yungas. All the collections have been found exclusively in this environment, on an altitudinal gradient between 400 and 1,000 m asl, in mature and well-preserved forests. Seven collections (1949-2011) from five localities in Argentina are known for this species; two collections from El Rey National Park (Salta), two collections form Calilegua National Park (Jujuy), two collections of protected areas of Tucuman province and one collection from an unprotected area in the Catamarca province.

Piedmont Forests have lost 90% of their original area, being replaced by sugar cane and transgenic cultivars of soybean (Malizia et al. 2012), therefore, the species is likely present in up to 150 areas in Argentina and Bolivia, based on how little of the  natural environments is left that contains the required conditions for this species to live.

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Population and Trends

Diacanthodes cerebriporoides is considered a rare species. Although it has large-sized basidiomes, only seven records of this species have been found in 70 years. In addition, soil and root metagenomic analysis in northwestern Argentina (Geml et al. 2014, Wicaksono et al. 2017) did not find OTUs associated with Diacanthodes species, which would indicate that it is not a common species. An average of two specimens were observed per site, but it is considered that it could appear 2 to 5 times more at each site with a greater sampling effort (5-10 specimens/site). Due to its solitary habit, it is estimated that currently there are between 1,000 and 3,000 mature individuals in one subpopulation. The three generation time period of this species is 30 years (Dahlberg and Mueller 2011), and it is predicted that, due to climate change, the area suitable for the specific forest which harbours this species will decrease by at least 15% in the next 30 years (year 2050) (Pacheco et al. 2010), causing a continuing decline in the species' population size.

Population Trend: decreasing

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Habitat and Ecology

Diacanthodes cerebriporoides grows in the ground of the Piedmont Forest, probably associated with roots, causing white rot (Rajchenberg and Robledo 2013 as D. novo-guineensis). No association to a specific host has been found.

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Threats

Yungas and especially the Piedmont Forests have been severely affected by agriculture, losing over 90% of the original area, and are being replaced by sugar cane and transgenic cultivars of soybean (Malizia et al. 2012). In addition, extensive livestock farming and forest fires are important disturbance factors in this ecosystem (Grau and Brown 2000, Brown et al. 2002, Pacheco et al. 2010, Malizia et al. 2012). In addition to anthropogenic disturbance, Pacheco et al. (2010) and Wicaksono et al. (2017) have recently predicted, based on modelled present and future distributions of tree species, that suitable habitat area for Piedmont and montane cloud forests will decrease due to climate change (Nouhra et al. 2018).

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Conservation Actions

Most of the collections were found in protected areas, therefore, the main action to prevent a possible decline of the species is the preservation of quality of habitat. In addition, considering that, in general, the Piedmont Forest is located on the limits of protected areas where there is an anthropogenic influence, it is suggested to reinforce the controls in these zones so that the protection of the species is effective. In addition, reinforcement policies that stimulate citizen science, making the community know, value and collaborate in the conservation of species would be useful. To achieve the conservation of the species, it is also necessary to know more precisely the way of life of the species, particularly if it presents any specific association with any host. In addition, it is essential to confirm if its distribution extends to the piedmont forests of other regions of the Yungas.

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Use and Trade

No use/trade is known.

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Source and Citation

Niveiro, N., Pelissero, D., Maubet, Y., Ranieri, C., Robledo, G. & Torres, D. 2023. Diacanthodes cerebriporoides. The IUCN Red List of Threatened Species 2023: e.T238222645A245224466. https://dx.doi.org/10.2305/IUCN.UK.2023-1.RLTS.T238222645A245224466.en .Accessed on 6 January 2025

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• Country occurrence