Assessment Notes

Justification

Russula alnijorullensis is an ectomycorrhizal species associated with Aliso del Cerro forests (Alnus acuminata), in the cloud forests of northwest Argentina and Bolivia (Morrone 2002). Despite its conspicuousness and sampling efforts, only eleven collections (1949-2011) are known for this species. The species is likely present in approximately 60 sites in Argentina and Bolivia, based on occurrences of Alnus acuminata within the southern Yungas (Wicaksono et al. 2017). This host species is distributed in the cloud forests that are located on the border between the montane forest and the grassland, often in ravines, which generate a prosperous microclimate for the species. It is inferred that currently there are no more than 10,000 mature individuals of R. alnijorllensis and is predicted that the area suitable for the specific forest will decrease by 25-50% in the next 30 years (year 2050) (Wicaksono et al. 2017), causing a suspected population size reduction of c.30-49% over the next three generations (50 years). It is assessed as Vulnerable under criteria A3c; C2a(ii).

---

Geographic range

Eleven collections (1949-2011) are known for this species, from Tucuman and Catamarca provinces in Argentina and one photographic record from Bolivia in iNaturalist. Russula alnijorullensis is an endemic species of the montane forests of the southern Yungas. Since this species has an ectomycorrhizal habit, its distribution pattern is likely related to the distribution of its host, Alnus acuminata, which is distributed throughout the Andean countries and Central America, up to Mexico (according to GBIF there are 525 observations from northwest Argentina to Mexico). Nevertheless, considering the records of R. alnijorullensis, its distribution might be restricted to the southern Yungas, which encompasses the cloud forests of northwestern Argentina and Bolivia (Morrone 2002). Therefore, the species is likely present in approximately 60 sites in Argentina and Bolivia, based on occurrences of Alnus acuminata within the southern Yungas (Wicaksono et al. 2017).

---

Population and Trends

Russula alnijorullensis is considered a rare species. Although it has medium-sized basidiomes and striking colours, no abundant records of this species have been found. In addition, soil and root metagenomic analysis of Alnus acuminata forests carried out in northwestern Argentina (Becerra et al. 2005, Geml et al. 2014, Wicaksono et al. 2017) did not find OTUs associated with Russula species, which could 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 5 to 25 times more at each site with a greater sampling effort (20-50 specimens/site). Due to its solitary habit, and using the methodology of Dahlberg and Mueller (2011) it is estimated that currently there are between 2,400 and no more than 10,000 mature individuals, all in one subpopulation. The three generation time period of this species is 50 years (Dahlberg and Mueller 2011), and it is suspected the area suitable for the specific forest which harbours this species will decrease by 25-50% in the next 30 years (year 2050) (Wicaksono et al. 2017). While accurate translation across to a population size reduction of R. alnijorullensis over three generations is difficult, it is suspected that there would be a reduction of at least 30-49% over three generations.

Population Trend: decreasing

---

Habitat and Ecology

Russula alnijorullensis is an ectomycorrhizal species associated with Aliso del Cerro forests (Alnus acuminata) in the montane cloud forests of the southern Yungas.

---

Threats

Russula alnijorullensis is associated with Alnus acuminata, its ectomycorrhizal species. This host species is distributed in the cloud forests that are located on the border between the montane forest and the grassland, often in ravines, which generate a prosperous microclimate for the species. One of the main threats to this ecosystem is climatic change, which is predicted to alter environmental conditions in such a way to make it easier for habitat shifting of the montane forest from a lower altitude, displacing the cloud forests at higher altitudes. Current and future (year 2050) habitat models developed for A. acuminata predict a 25–50% decrease in suitable area (Wicaksono et al. 2017). The species is also threatened by its proximity to anthropic influence caused by cattle grazing, deforestation and prescribed fires.

---

Conservation Actions

Most known collections of Russula alnijorullensis 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, cloud forest is located on boundaries of protected areas where anthropogenic influence exists. Considering this, it is suggested to reinforce controls in these areas so the protection of the species is effective. Furthermore, it is essential to strengthen policies that stimulate citizen science, making the community know, value, and collaborate in the conservation of species. To achieve the conservation of the species, it is essential to confirm if its distribution extends to the cloud forests of other regions of the Yungas.

---

Use and Trade

No use/trade is known.

---

Source and Citation

Niveiro, N., Maubet, Y., Ranieri, C., Pelissero, D. & Torres, D. 2023. Russula alnijorullensis. The IUCN Red List of Threatened Species 2023: e.T238218561A245224791. https://dx.doi.org/10.2305/IUCN.UK.2023-1.RLTS.T238218561A245224791.en .Accessed on 3 January 2024

---

• Country occurrence