Assessment Notes

Justification

Durianella echinulata is a gasteroid fungus found in Peninsular and Bornean Malaysia. It has only been documented from three sites, once each in 1932, 2005 and 2006. Because of the inconspicuousness of this fungi it is likely that the species is more common than reported and the population size is estimated to be up to 30,000 individuals. Though this species’ population size is difficult to estimate due to the absence of more current records, the levels of deforestation in the area suggest that it is likely in decline. A past and ongoing population size reduction due to loss of habitat and obligate host trees is expected to be above 30% for a 50 year (three generations) period and therefore D. echinulata qualifies as Vulnerable A2c+4c.

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Taxonomic notes

It is the only member of the monotypic genus Durianella, created in 2008 using morphological and molecular data (Desjardin et al. 2008).

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Geographic range

This species is known from Peninsular Malaysia (specifically Sungai Nipah in Kemaman, Trengganu, and the Hutan Lipur Sungai Congkak Forest Reserve in Selangor) and from one unspecified site in Malaysian Borneo (mapped to a centroid point) (Corner and Hawker 1953, Desjardin et al. 2008).

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Population and Trends

This species has only been documented from three sites in Malaysia, once in 1932, and then in 2005 and 2006. The authors of Desjardin et al. (2008) are not aware of any attempts at finding it since. For this reason, it is difficult to estimate whether this is a rare species, or if it is under-documented. Considering that the species is only known from three sites, and the inconspicuousness of this fungus, it is not possible to confidently estimate population size. However as the species occurs in secondary forests it likely occurs in low numbers across a wide area. The population size is thus estimated at 30,000 mature individuals (3 known sites x 10 mature individuals per site x 1,000 multiplier to account for potential additional sites), using the guidelines in Dahlberg and Mueller (2011). However, this assumes that all sites have remained intact, with mature, fruiting individuals, including the one found in 1932 (Sungai Nipah).

Given the deforestation in Malaysia the population of Durianella echinulata is inferred to be in decline. Data from Estoque et al. (2019) can be used to estimate a 33% decrease in forest cover in Malaysia from 2000 to 2050. This corresponds to three generations (50 years for ectomycorrhizal fungi) (Dahlberg and Mueller 2011). For Borneo specifically, a decrease in 33% of forest area between 1973 and 2015 is estimated using data from Gaveau et al. (2016). As this fungus is obligately associated with its host trees, the population size of D. echinulata is suspected to have decreased more than 30% due to habitat loss and associated loss of hosts, and this loss is predicted to continue.

Population Trend: decreasing

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Habitat and Ecology

Durianella echinulata is an epigeous gasteroid fungus that grows on soil, solitarily or in small clusters. It was found in secondary forest and is thought to be ectomycorrhizal with Shorea spp. (Dipterocarpaceae) (Desjardin et al. 2008).

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Threats

Southeast Asia is a major global deforestation hotspot. Both Peninsular Malaysia and Borneo have suffered significant deforestation and conversion of forest areas to oil palm and pulpwood industry plantations in the last decades (Gaveau et al. 2016). This decline in areas of suitable habitat and obligate hosts is likely causing a decline in population size for Durianella echinulata.

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Conservation Actions

One of the sites where Durianella echinulata was found is part of the Hutan Lipur Sungai Congkak Forest Reserve. Nevertheless, this site should be monitored, along with the Trengganu site. It is also essential to protect dipterocarp forests that may constitute a habitat for this species in order to halt its population decline. Known sites for D. echinulata need to be monitored to confirm the presence of fruiting individuals. Search efforts in areas of appropriate habitat and research into its ecology and habitat preferences are also needed to obtain better estimates of its distribution and population size.

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Source and Citation

Cunha, S.P. & Gonçalves, S.C. 2024. Durianella echinulata. The IUCN Red List of Threatened Species 2024: e.T258432990A258434707. .Accessed on 28 June 2024

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• Country occurrence