I cannot find reference for Tawau Hill location. For now it’s included in the map.
Known area of distribution is very small but I am assuming it is undersampled so I didn’t go for criterion C.
Chlorogaster dipterocarpi is a Southeast Asian species, found in Sabah in Borneo Island. It has very rarely been documented and is known from only 3-4 sites. As the species, while distinctive, is not very conspicuous it is likely undersampled and the population size is estimated to be 15000-20000. The population is likely to be in decline throughout its range due to the severe loss of lowland dipterocarp forest in Sabah. Population reduction is estimated be above 30% for a 50 year period, which qualifies this species as Vulnerable A2c+4c.
So far comprises a monotypic genus but material of a darker taxon that probably is congeneric has been collected in Papua New Guinea. No phylogenetic data is available. (Læssøe and Jalink, 2004)
This unusual species is likely to be declining throughout its range as a result of severe loss of lowland dipterocarp forest in Sabah, Malaysia, where it is only known from one area (Danum Valley).
Only known from 3- 4 sites, a maximum of three sites within the Danum Valley and one from Tawau Hills, both are protected areas in Sabah (Borneo), Malaysia.
Chlorogaster dipterocarpi has a very restricted distribution in Malaysia. It is only known from 2 to 3 sites within the Danum Valley - 2 identified in 1999 (Læssøe and Jalink, 2004), and a possibly third different site in 2014 (Mushroom Observer observation 308646) and 1 from Tawau Hill (REF). Its fruitbodies are difficult to mistake for other species, but are not particularly conspicuous resulting in a small number of documented observations and sites, in a small region. Population size is therefore estimated at 15000-20000 individuals (3-4 sites x 10 mature individuals x 500 multiplier), using Dahlberg and Mueller (2011) guidelines.
Even though the species has been found in protected areas, the considerable deforestation and loss of suitable habitat in Borneo is likely causing a decrease in the total population size. Gaveau et al (2016) estimated a decrease in 33% of forest area between 1973 and 2015 in the Borneo Island and 31% in the Sabah region alone. Over a 50 year period, 3 generations for a mycorrhizal fungi (Dahlberg and Mueller, 2011), population size is therefore expected to have a decreased above 30%. This is also in accordance with data and projections for Southeast Asia (Estoque et al, 2019) which can be used to estimate a 33% decrease in forest cover for a 50 year period from 2000 to 2050.
Population Trend: Decreasing
Probably mycorrhizal with Dipterocarpaceae. Found in old growth dipterocarp stands.
Southeast Asia is a major global deforestation hotspot, and Malaysia is one of the countries where this is most prevalent. Even though the species has been found in protected areas, its surroundings have suffered significant tree cover loss (Global Forest Watch, 2022) and vast areas of suitable habitat have been converted, due to oil palm and pulpwood industry plantations across the Borneo island (Gaveau et al 2016).
Chlorogaster dipterocarpi was found in protected areas – the Danum Valley Conservation Area and the Tawau Hills Park. It is essential to guarantee monitoring of the known populations and protection of these sites, but also other old growth dipterocarp stands in this region that may constitute a habitat for this species.
Given that there are so few known sites, it is important to monitor the known populations, and targeted search efforts are needed to confirm whether the distribution of the species is limited to these locations. Taxonomic study, including the darker specimens that have been collected in Papua New Guinea is needed.