Taxonomic Notes
The original description mentions that is is morphologically similar to other Brazilian Cantharellus species.
Justification
Cantharellus rubescens is known only from its type locality within the Caatinga, where was collected in 2011 and never found again. It was found growing gregariously to scattered under unidentified Fabaceae living trees in the Araripe-Apodi National Forest, a currently undersampled area. Despite the lack of data to infer its potential occurrence range, it is possible that the species occurs elsewhere in the Caatinga where its specific (and up to now unclear) biotic and abiotic requirements are met. The species produces large and conspicuous basidiomes with orange pileus and pale stipe, contrasting with soil and litter where it is found growing. It is possible that the species forms symbiotic relationships with an unknown plant host, as species within Cantharellus are often ectomycorrhizal. The species' rarity, despite its conspicuous basidiomes, and lack of distribution data hinders understanding of its potential distribution, ecology, and niche requirements. More efforts are required to understand C. rubescens' needs, past and current trends, and if it is facing threats. Therefore, C. rubescens is assessed as Data Deficient.
Geographic Range Information
The species is known only from its type locality, a Caatinga area within the Araripe-Apodi National Forest in Ceará State, Brazil. The region is extremely undersampled, representing a large knowledge gap for the Brazilian funga. Despite this, other Caatinga areas have been well sampled, and despite the species' basidiomes being conspicuous, it has never been collected again since 2011. Therefore, the species is considered rare, and due to a lack of data regarding its distribution and requirements, it is currently impossible to infer its potential distribution. Despite this, it is possible that Cantharellus rubescens is distributed throughout the Caatinga in areas with similar conditions as its type locality.
Population Information
In the 14 years since the holotype collection of Cantharellus rubescens, it has never been registered again. Its first and only collection was made in Araripe-Apodi National Forest, a conservation unit that allows sustainable use of its area and resources, and therefore it is not strictly preserved from human disturbances. The species produces fleshy basidiomata with a deep and bright orange colour, contrasting with its substrate, soil under unidentified Fabaceae trees, its expected host. The paucity of sampling in the species' type locality contributes to its decade-long lack of recollection, but other Caatinga areas are comparatively well sampled and the species has never been found in these areas, allowing the species to be considered potentially rare. Considering the current lack of knowledge regarding the species, it is impossible to infer its population size, potential distribution, and trends, or understand its niche requirements and ecology. Nonetheless, it is possible that the species occurs in adjacent areas surrounding its type locality and other Caatinga regions that hold the same biotic and abiotic conditions as its known occurrence site. Despite this, the species could potentially be under threat, as habitat quality is directly linked to species occupation (Berglund and Jonnson 2003, Haddad et al. 2015), and the Caatinga is expected to suffer important pressures that will translate into high loss of area (Câmara et al. 2015).
Habitat and Ecology Information
Cantharellus rubescens was reported as growing gregariously to scattered among living unidentified Fabaceae trees in a Caatinga area within Araripe-Apodi National Forest. Despite the lack of data to infer its potential occurrence range, it is possible that the species occurs elsewhere within the Caatinga where its specific biotic and abiotic requirements are met. The species produces large and conspicuous basidiomes with deep and bright orange pileus that fades to a light orange in the stipe, clearly contrasting with its substrate. It is possible that the species forms symbiotic relationships with an unknown plant host, perhaps the unidentified Fabaceae species that it grows underneath, as species within Cantharellus are often ectomycorrhizal.
Threats Information
As there is a lack of data on the population parameters and requirements of Cantharellus rubescens, it is impossible to understand and identify the threats to its population. Despite this, the species is currently considered endemic to the Caatinga, a Brazilian ecoregion that is projected to face an increase in current anthropogenic pressures associated with land use, which will translate into a high loss of area (Câmara et al. 2015), potentially threatening the species, as habitat quality is linked to species occupation (Berglund and Jonnson 2003, Haddad et al. 2015).
Use and Trade Information
No use/trade is known, but Cantharellus species are generally edible and consumed locally.
Conservation Actions Information
Direct and precise conservation actions aiming to preserve Cantharellus rubescens population are currently hindered by lack of knowledge on the species' distribution, population size and trends, and potential niche. However, a cautionary solution would include its type locality and adjacent areas strict protection, where there is a bigger probability of C. rubescens occurrence, as the Araripe-Apodi National Forest is a conservation unit that allows sustainable use of its area and resources, and current legislation lacks reinforcement. Further research and sampling efforts are needed in order to better understand the species' distribution and potential niche, which would in turn enable population inferences and threats mapping. Additionally, Cantharellus species are generally symbionts, thus ecological research regarding the species' potential hosts would increase its ecological and niche understanding.
