Cantharellus subcibarius is a tropical chanterelle of diptercarp forests in Borneo. Further records from outside of this range have either not been confirmed as this species, or are highly unlikely to be this species and have not been included in the assessment. Its known records from from the northern part of the island, and the overall population size estimated to fall in the range of 1,400-5,000 mature individuals, with no subpopulation containing more than 600-2,000 mature individuals. Ongoing forest loss is thought to be leading to population declines, and so precautionarily using the lower end of the population size estimate, C. subcibarius is assessed as Vulnerable under criterion C2a(i).
It is possible that this species has also been described under another name (I. Olariaga Ibarguren in litt. 2022).
The type collection of this species comes from Kinabalu in Sabah, Borneo (Buyck et al. 2021), and has been considered to only occur in Malaysia by some (e.g. Wang et al. 2023). However, it has also been confirmed from Brunei, in Temburong District (Roberts and Spooner 2000). Records from New Guinea (Corner 1970 per Eyssartier et al. 2009) have different features and are unlikely to represent the same species (I. Olariaga Ibarguren in litt. 2022), and so are not included. Reports of the species from South Asia (Nepal; Pandey and Budhathoki 2007) are also excluded due to the great distance from the type locality with no other confirmed continental records of the species. Genetic work on specimens from this region is required to confirm whether they truly are this species.
This species has been very rarely recorded, with confirmed records only from Brunei and Kinabalu in Sabah. Looking at the available habitat between these sites in northern to north-western Borneo, there is only a limited amount of suitable habitat, and given the low reporting frequency a total of 70-100 sites for the species may be available within this range. At each site there may only be two to five functional individuals, and using the scaling factor of 10 mature individuals per functional individual (Dahlberg and Mueller 2011), this would give a total population size of 1,400-5,000 mature individuals. Looking at the distribution of the remaining forest cover (see World Resources Institute 2024), the population is likely fragmented into multiple subpopulations, with the largest likely containing 30-40 sites (equivalent to 600-2,000 mature individuals based on the above calculations).
With ongoing habitat loss, the population of Cantharellus subcibarius is thought to be in decline. Within the mapped range there has been 17% decline in forest cover between 2001-2022 (World Resources Institute 2023), which would equates to a reduction of 40.5% over three generations (50 years; per Dahlberg and Mueller 2011). However, the rate of forest loss at higher altitudes has been less than that of lowlands, and not all forest cover loss is of primary forest. Looking at primary forest cover losses in Sabah, the proportion of total forest cover loss that was primary forest in this time period was 20% (World Resource Institute 2024); and if that is representative for this species’ distribution then the forest cover within its range will be declining at a rate of c. 8% over three generations. While there may not be a direct 1:1 relationship between forest cover loss and population declines, this value is used as a precautionary suspected rate of population decline.
Population Trend: Decreasing
This species can be found on the soil, amongst leaf litter (Roberts and Spooner 2000) in association with dipterocarp trees (Eyssartier et al. 2009). It is presumed to be ectomycorrhizal with these dipterocarps.
The Sundaland region is considered to be a critical ‘hotspot’ for conservation (Myers et al. 2000), and there is evidence of rapid forest cover loss within the range of this species (see World Resources Institute 2024). The major drivers of such habitat loss in the region are logging and agricultural expansion (see e.g. Curran et al. 2004), and particularly for this species, around the Mesilau area near Kinabalu, there has already been significant land use change, with habitat loss driven by threats such as tourism development and agriculture (Tsen et al. 2021).
Protection of further areas of remaining primary forest in north-western Borneo would likely benefit this species, as could suitable management of the land (e.g. instead of clear-felling, leaving corridors of primary forest). Engagement with local stakeholders will also be required.
Genetic and taxonomic work is required in order to identify whether this species has been described under another name as well, and to investigate if records from South Asia truly refer to this concept. Further surveys in northern Borneo would also be useful to get a clearer indication of the full distribution of Cantharellus subcibarius there, as well as getting a clearer estimate of the population size and trend.
There are no specific records of this species being used in Borneo. In Nepal collections recorded as Cantharellus subcibarius are considered edible (Pandey and Budhathoki 2007), but as noted above, whether these truly match to C. subcibarius is uncertain.