Cantharellus ianthinus has only been recorded from Malaysia, with most sites from Peninsular Malaysia, but also recorded from Sabah on Borneo. It is a scarce species, and depending on the full range of the species it is estimated that the population size could fall within the range 1,010-12,000 mature individuals. Ongoing habitat loss within its range means the species is in decline, suspected to be at a rate of 20-29% over three generations. Taking a precautionary approach, and using the lower end of the population size estimate, with no single subpopulation containing more than 500 mature individuals, C. ianthinus is assessed as Vulnerable under criterion C2a(i).
This species is thought to occur within the tropical rainforests of Malaysia and although it has been described as ‘scarce’ in the past (Corner 1970), more recent collections of this species have been made within the Pasoh Forest Reserve in Malaysia every year between 1992 and 1997 (See et al. 2003). There are scattered records of the species from Peninsular Malaysia, as well as from Mt. Kinabalu in Sabah, Borneo (Malaysia Biodiversity Information System 2023).
Given the widespread habitat loss in the region, the species is in decline. It is difficult to get an specific, accurate rate of habitat loss, with the range of the species still uncertain, but based on the relatively rapid loss of forest cover (see World Resources Institute 2023), the population size may be suspected to be declining relatively rapidly too. Looking at data for Peninsular Malaysia, Negeri Sembilan saw a 14% decline in its primary forest between 2001 and 2022, while Perak saw a decline of 9.0%, Selangor by 5.5% and Pahang by 20% (World Resources Institute 2023). Assuming a linear decline, these would equate to declines of 33.3%, 21.4%, 13.1% and 47.6% respectively, over three generations (50 years, per Dahlberg and Mueller 2011). The subpopulation from Mt. Kinabalu is likely to be relatively stable given its presence within a protected area, but if it is more widespread in Sabah on Borneo then it may be facing a similar rate of decline there. There is, overall, uncertainty over the true rate of decline figure and more research is needed, but it is very tentatively assumed that the overall rate may fall in the range 20-29% over three generations.
This is a scare species, with only single or two fruiting bodies produced (Corner 1970). Based on this, the scaling factor for functional individuals to mature individuals is likely to fall towards the lower end of the scale in Dahlberg and Mueller (2011). There are likely to also be only a small number of functional individuals per site (on average c. five) and so a tentative estimate of 10 mature individuals per site can be made. Suitable habitat across Peninsular Malaysia could provide c. 100-200 sites giving a total population size there of 1,000-2,000 mature individuals, split into multiple subpopulations, with no single subpopulation containing more than 500 mature individuals.
The site at Mt. Kinabalu would add a further 10 mature individuals, assuming a similar population density there, giving a total population size of 1,010-2,010. However, there are extensive areas of suitable habitat on Borneo (see World Resources Institute 2023), and so if the species were to be widespread on the island the total number of sites there could easily be 1,000 or more. This would then given maximum total population size range of 11,000-12,000 mature individuals. For the sake of this assessment a precautionary approach is taken and the minimum estimate range of 1,010-2,010 mature individuals is used. However, further survey work on Borneo are strongly recommended to get a clearer idea of the true population size.
Population Trend: Decreasing
This species is known to occur within the tropical lowland rainforests of Peninsular Malaysia (See et al. 2003). Based on its collection around Mt. Kinabalu it is assumed that it will also occur in montane rainforest as well.
This species exists under protection of the Pasoh Forest Reserve. The state of wild populations of this species are currently poorly understood. It is likely that this species could be threatened by logging and agricultural expansion (e.g. Curran et al. 2004, Shevade and Loboda 2019).
Ensuring effective protection of remaining tracts of primary forest within its range should benefit this species.
Further research is required in order to confirm the status of this species in the wild, and to assess the threats which may be affecting it. Further recent collections and molecular data are needed to compare it properly to other Asian species of the section Amethystini (I. Olariaga Ibarguren in litt. 2022).