Craterellus verrucosus is a chanterelle species of Southeast Asia, occurring on Penang island, Peninsular Malaysia and on Borneo (Sabah and East Kalimantan). Its lowland primary dipterocarp forest habitat is under threat from logging and agricultural expansion and being an ectomycorrhizal fungus, it is suspected to be undergoing a relatively rapid decline in line with its habitat. While there is some uncertainty surrounding the full distribution of the species and its habitat requirements, a conservative approach is taken here assuming it is restricted to primary forest. As such an approximate past and ongoing decline approaching 30% is suspected over three generations (50 years). Therefore, C. verrucosus is assessed as Near Threatened under criteria A2c+4c.

The type specimen of this species was found near Penang Hill, Penang, Malaysia (Massee 1906). Two further specimens were collected in 1997, in the Pasoh Forest Reserve, Peninsular Malaysia (GBIF 2020). It has also been recorded from Borneo in the Danum Valley Conservation Area in Sabah (Hjortstam et al. 1990) and Wanariset Samboja in East Kalimantan (Smits 1994). With this spread of records it is assumed to occur at further localities across Peninsular Malaysia and Borneo, at least.

There are very limited population data for this species, and so an accurate estimation of the population size cannot be made. However, if, as suspected, it is found across suitable forest habitat in Peninsular Malaysia and Borneo then it is unlikely to have a small population size. Given the widespread forest cover loss in the region, it may be suspected that the population is in decline. It is difficult to get a 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, the two provinces where it has been reported there have seen the loss of 3.1% (Palau Pinang) and 14% (Negeri Sembilan) of their primary forest between 2001 and 2022. Assuming a linear decline, these would equate to declines of 7.4% and 33.3%, respectively, over three generations (50 years, per Dahlberg and Mueller 2011). Primary forest declines in other provinces in Peninsular Malaysia, between these two known sites are of a similar magnitude (e.g. Perak declined by 9.0% between 2001 and 2022, Selangor by 5.5%; World Resources Institute 2023). When looking at all forest cover (at 30% canopy cover) the declines are greater between 2001 and 2022 (Palau Pinang - 24%; Negeri Sembilan - 49%; World Resources Institute 2023).

In Borneo, declines have also been at a similar rate, with primary forest loss in Sabah at 11% between 2001 and 2022 (27% of total forest cover lost) (World Resources Institute 2023), equating to a decline in primary forest of 26.2% over three generations. World Resources Institute (2023) also reports a loss of 31.2 kha of primary forest in 2022 for East Kalimantan, which would roughly equate to a loss of 0.2% of the primary forest remaining there per 2001 figures, and if that year were an average year, then the total loss over three generations would be c. 12.4%. However, it appears that 2022 had relatively low levels of forest cover loss compared to earlier years of the 21^st century (see World Resources Institute 2023) and so the total loss of three generations will be higher than this.

Overall, there is some uncertainty in the overall rate of primary forest loss within its range and how this would translate to population loss, and indeed there is uncertainty over whether the species is restricted to primary forest. The conservative approach taken here is to assume that it is restricted to primary forest, and that overall the population has undergone a past decline, and is undergoing a continuing decline of approximately approaching 30% over three generations.

This species is an ectomycorrhizal fungus found in clusters on the ground (Massee 1906, Hjotstam et al. 1990) in primary lowland dipterocarp forest (see Smits 1994, GBIF 2020).

The Sundaland region is considered to be one of the most critical 'hotspots' for conservation (Myers et al. 2000). The major drivers of this habitat loss are for logging and agricultural expansion (e.g. Curran et al. 2004, Shevade and Loboda 2019).

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This species is known from Pasoh Forest Reserve and Danum Valley Conservation Area. Further protection of remaining areas of primary forest within its range will likely benefit this species. Further information regarding this species’ distribution, and whether there are any specific threats it faces would be useful. It will also be important to ascertain if this species may be restricted to areas of primary forest, or whether it can persist in secondary forest, or even in plantations etc.