Assessment Notes

Justification

Chlorogaster dipterocarpi is a Southeast Asian species, reported only from Sabah State in Borneo. It has very rarely been documented and is known from only three to four sites. As the species, while distinctive, is not very conspicuous it is likely under-sampled and the population size is estimated to be 15,000-20,000 mature individuals. The population is likely to be in decline throughout its range due to the severe loss of lowland dipterocarp forest in Sabah. The past and ongoing population reduction is suspected be above 30% for a 50 year (three generations) period, which qualifies this species as Vulnerable A2c+4c.

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Taxonomic notes

This currently comprises a monotypic genus but material of a darker taxon that probably is congeneric has been collected in Papua New Guinea. No phylogenetic data are available (Læssøe and Jalink 2004).

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Geographic range

This species is only known from two to four sites; at least two, and a maximum of three, sites within the Danum Valley and one unverified site from Tawau Hills. Both are protected areas in Sabah (Borneo), Malaysia.

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Population and Trends

Chlorogaster dipterocarpi has a very restricted distribution in Malaysia. It is only known from two to three sites within the Danum Valley - two identified in 1999 (Læssøe and Jalink 2004), and a possible third different site in 2014 (Russell 2018) and one from Tawau Hill (unverified). Its sporocarps are difficult to mistake for other species, but are not particularly conspicuous resulting in a small number of documented observations and sites, from a small region. The population size is therefore estimated at 15,000-20,000 mature individuals (3-4 sites x 10 mature individuals per site x 500 multiplier for potential unrecorded sites), 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 Borneo and 31% in the Sabah region alone. Over a 50 year period, three generations for a mycorrhizal fungi (Dahlberg and Mueller 2011), the population size is therefore expected to have decreased by >30%, assuming a direct relationship between habitat loss and population declines. 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

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Habitat and Ecology

It is probably mycorrhizal with Dipterocarpaceae, and is found in old growth dipterocarp stands.

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Threats

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 (World Resources Institute 2022) and vast areas of suitable habitat have been converted due to oil palm and pulpwood industry plantations across Borneo (Gaveau et al. 2016).

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Conservation Actions

Chlorogaster dipterocarpi has been found in protected areas – the Danum Valley Conservation Area and potentially in the Tawau Hills Park. It is essential to monitor the known subpopulations and protect these sites, as well as 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 subpopulations. Targeted search efforts are needed to confirm whether the distribution of the species is limited to these locations.

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Source and Citation

Cunha, S.P. & Gonçalves, S.C. 2024. Chlorogaster dipterocarpi. The IUCN Red List of Threatened Species 2024: e.T70416597A258434895. .Accessed on 28 June 2024

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• Country occurrence