Lactarius kesiyae is originally described from collections found in Pinus kesiya forest in Vietnam and Northern Thailand (Wisitrassameewong et al. 2015). This species is very similar to L. cinnamomeus (Wang 2007). However, the macromorphological description of the holotype specimen of L. cinnamomeus in Wang (2007) is incomplete due to the poor condition of the specimen. Microscopically, both species are similar in some aspects such as spore ornamentation, spore size, pleuromacrocystidia and pileipellis. There are slight microscopic differences e.g. spores in L. cinnamoneus are more ellipsoidal and the presence of yellowish brown contents in pleurocystidia. L. cinnamomeus is reported from Castanopsis+Quercus dominated forest with scattered Pinus yunnanensis or mixed forest with Quercus, Keteleeria, P. yunnanensis and Castenea trees (Wang 2007).
Unfortunately, there is no available DNA sequence of the holotype specimen to compare with L. kesiyae phylogenetically.
The species also recalls L. glutininitens However, L. glutininitens differs by having spores with isolated wart and ixotrichoderm pileipellis.
The species is distributed in coniferous forest or mixed forest with deciduous trees and coniferous trees in Thailand, Vietnam, China and South Korea. Although there is not clear evidence on the trend of the population, however, severe problem in habitat loss e.g. land use change, deforestation and the occurrence of wildfire in large area in SE Asia are causing a decrease in population.
The species is widely distributed in Asia. Up to present, the species is found in Thailand and Vietnam (Wisitrassameewong et al. 2015), China, Jeju Island of South Korea (Lee et al. 2018) and India.
L. kesiyae is a distinctive species and is recorded in several locations in 5 Asian countries. In Vietnam, L. kesiyae is recorded from Pine forest in Lang Biang National park. In Thailand, most records were found in northern Thailand, presented in Pine forest or Fagaceae forest with scattered Pinus trees. In South Korea, the fungus is restricted in an isolated island, Jeju-do. It is reported from mixed forest with evergreen trees and P. densiflora.
The recently available ITS sequences obtained from sporocarps found in China proved the occurrence of the species in some localities e.g. ZunYi, Jiangxi, Guizhou, Hunan. Whereas, the ITS sequences of Indian collections, from Arunachal Pradesh and Uttarakhand, grouped in L. kesiyae clade.
Population Trend: Uncertain
Apparently, Lactarius kesiyae is an ectomycorrizal mushroom species associated with coniferous species. It grows under pure stand of Pinus kesiya in Thailand and Vietnam. In South Korea, the species grows in mixed forest with evergreen trees and Pinus densiflora. Recent DNA sequences of ECM samples from China (personal analysis) proved the association with coniferous trees e.g. Pinus massoniana, Pseudotsuga sinensis, Keteleeria evelyniana. In addition, Le (2007) found that the species grows in mixed montane forest with Fagaceae and Pinus trees. In India, the species is found in Pinus forest and mixed forest under Quercus tree.
The main threat to Lactarius kesiyae is declining habitat and fragmentation due to the decrease of populations of host trees caused by deforestation and wildfires. For example, in Northern Thailand, Pinus forests outside national park have been destroyed gradually by local people.
Habitat protection and management are needed. In Thailand, most Pine forest are in protected areas, however, Northern Thailand has been experiencing the occurrence of wildfires in many areas in dry season for years. This incident frequently caused by locals living in rural community around forest that use fires for some reasons such as land preparation for crop cultivation, promotion of mushroom fruitification and hunting wildlife. Therefore, the efficient forest management planning is necessarily implemented in order to reduce habitat loss. In addition, formal education and awareness to locals are also necessary.
Molecular study of the type of L. cinnamomeus and detailed comparison between L. cinnamomeus and L. kesiyae are required. To understand more about the host preference and population size, host association of the species in mixed forest habitat should be studied.
Wang (2007) Type studies of Lactarius species published from China. Mycologia 99:2, 253-268.
Wisitrassameewong K., Nuytinck J., Le H.T, De Crop E., Hampe F., Hyde K.D., Verbeken A. (2015). Lactarius subgenus Russularia (Russulaceae) in South-East Asia: 3. new diversity in Thailand and Vietnam. Phytotaxa 207(3): 215-241.