• Proposed
  • Under Assessment
  • DDPreliminary Assessed
  • 4Assessed
  • 5Published

Russula siamensis Yomyart, Piap., Watling, Whalley & Sihan.

Search for another Species...

Scientific name
Russula siamensis
Yomyart, Piap., Watling, Whalley & Sihan.
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Preliminary Assessed
Preliminary Category
Proposed by
Cherdchai Phosri
Cherdchai Phosri
Gregory Mueller
Rosnida Tajuddin, Andrew Anak Ngadin, Gerhard Kost, Annya Ambrose, SuSee Lee, Olivier Raspé, Amy Choong, Siti Nordahliawate Mohamed Sidique
Roy Halling

Assessment Notes

Reports from only one site, in a Dipterocarpus alatus plantation in eastern Thailand.  D. alatus is commonly used as a plantation species in Thailand.  It also can be found growing in disturbed sites outside of plantations. Nothing in iNaturalist, three occurrences from Thailand in Gbif without detail on sites.
this species classified in DD, because it need information on distribution and ecology.  however it is very unusual species, no one in our group had ever seen a report of an annulate Russula from the SE Asia but R cingulate is reported from PNG also annulate species. 

Taxonomic notes

The species characterised by a distintcly annulate stipe. overall features are closely R. cingulata described from Papua New Guinea but in minute there are important differences in that the pileus does not disrupt into flakes or in to scale as R. cingulata. Further basidiospores are larger and less strongly ornamented.

Why suggested for a Global Red List Assessment?

It is unique in Thai mycota. This fungus has only been recorded growing in association with Dipterocarpus alatus (Dipterocarpaceae) from only one plantation of the Royal initiative project in the Eastern area of Thailand.

As demonstrated by Disyatat et al. (2016)  that fragmentation in a dry dipterocarp forest can influence patterns of ectomycorrhizal fungal diversity. Varying results indicate both that different stages of the dipterocarp life cycle may be differentially affected by disturbance and fragmentation and that the degree of disturbance and the environmental setting also play a role in determining tangible effects on dipterocarp communities.

The species is inferred to be rare, and under threat by deforestation and forest fragmentation.

Geographic range

Reported from Eastern part of Thailand in 2006 (Yomyart et al. 2006). Now known only at one plantation on a dipterocarps alatus , a commonly used in plantations.

Population and Trends

So far known only from 1 site in Chacherngsoa Province, Eastern part of Thailand. In site, fruiting bodies occur regularly, but population size is estimated to a maximum of 3-5 individuals.  The putative host tree is commonly found throughout the area.  So habitat for additional sites of Russula siamensis exist widely.

Population Trend: Uncertain

Habitat and Ecology

The fungus grows in small groups on bare sandy loam soil under Dipterocarpus alatus, which prefers moist soil, and with ground cover of Malaysian grass. Presumably ectomycorrhizal with Dipterocarpus alatus. The host occurs only in the everegreen forests of Myanmar and Thailand and Andaman Islands.

Subtropical/Tropical Dry Forest


In the area where this species is known to occur, forests continue to be degraded by human activities (e.g., rubber plantation). In a dry dipterocarp forest, Disyatat et al. (2016) further demonstrated that fragmentation can influence patterns of ectomycorrhizal fungal diversity.

Trend Unknown/Unrecorded

Conservation Actions

Species recovery

Research needed

Comprehensive surveys and inventories for Thailand, and the SE region are needed to determine the occurrence and distribution of the fungus.
Further annulate Russula species are needed for sequence.

Population size, distribution & trends

Use and Trade




Yomyart S, Piapukiew J, Watling R, Whalley AJS, Sihanonth P. 2006. Russula siamensis: a new species of annulate Russula from Thailand. Mycotaxon 95: 247-254.

Disyatat NR, Yomyart S, Sihanonth P, Piapukiew J. Community structure and dynamics of ectomycorrhizal fungi in a dipter- ocarp forest fragment and plantation in Thailand. Plant Ecology & Diversity 9(5–6). 2016:577–588.

Country occurrence

Regional Population and Trends

Country Trend Redlisted