Tricholoma mesoamericanun is endemic to Mexico. It belongs to the matsutake species complex which is one of the most valued edible mushrooms globally.
Because its export value, it has been extensivelly searched and detailed records of export volumes are available.
This is one of the only edible ectomycorrhizal species whose extensive collection do kill the mycelia affecting its populations.
As its market has not declined, the export volumes are a good proxy of the decline of its reproductive populations.
Tricholoma mesoamericanum should be listed under the Endangered (EN) category under A2d criteria because based in the actual levels of exploitation it has suffered a conservative estimated population reduction of more than 50% in the past 30 years and the causes of that decline have not ceased.
Tricholoma mesoamericanum is a member of the T. matsutake species complex. It was described in 2017; before it was considered to be T. magnivelare.
Pileus convex, expanding to planoconvex, becoming depressed at center in older specimens; surface white with pale yellow to brown fibrils, more evident in age. Partial veil forming a white, cottony annulus in the upper part, with yellow or brown spots all over in age. Context white or very pale yellow, sweet with perfume-spicy characteristic odor. Its tendency to become brown overall with age helps to distinguish it from T. murrillianum and T. magnivelare, and the less scaly aspect of the pileus helps distinguishishing it from T. magnivelare and T. matsutake (Trudell et al. 2017).
Tricholoma mesoamericanum was known as T. magnivelare until 2017. This species is the subtropical representative of the Tricholoma matsutake complex in Mexico. All the American species of this complex (T. magnivelare, T. mesoamericanum and T. murrillianum) are included and exploited together with T. matsutake in the biocultural species “matsutake”. All the species within “matsutake” are threatened by the same economic interests and by the same bad recollection practice of raking the soil to expose young mushroom “buttons”. The “buttons” reach more than $500 US per kg in Japanese markets. Because of this, in Mexico the populations are being overexploited and the raking practice is killing the mycelia. So this is one of the best documented cases of mushroom severe population declines due to intensive collection bad practices. In Mexico, reproductive populations have been reduced likely 50% in the last 20 years.
Tricholoma mesoamericanum is only found in Mexican subtropical and temperate pine forests, most frequent in the states of Jalisco, Hidalgo, Oaxaca, Veracruz, and Estado de Mexico but also occurs at least in the states of Guerrero, Michoacán, Puebla, Colima, Morelos, and Tlaxcala. Chihuahua and Durango materials should be revised in detail to determine whether they belong to T. mesoamericanum or the western Northamerican species Tricholoma murrillianum.
In Jalisco state are known three subpopulations: at the Tequila volcano, at Cumbre de Guadalupe and an other one in Sierra Quila. In the Northwest Michoacan there is one subpopulation near Tuxpan in a very damaged forest and an other one in Tupataro. In Hidalgo there are conserved subpopulations in Huasca de Ocampo and in el Zembo, and some declining subpopulations in El Guajolote and Cerro de las Navajas. Veracruz has three endangered populations between Xalapa city and Jilotepec, near Las Vigas de Ramírez, and in Reserva San Juan del Monte; other subpopulations registered in the 80s have already disappeared because change in land cover to agriculture and cattling. Oaxaca has registered populations in Sierra Norte de Oaxaca, the Benito Juarez National Park, Santa María Peñoles, in Tlaxiaco, and in the Sierra Madre del Sur in Nochixltlan (GBIF 2018).
All known subpopulations of T. mesoamericanum happen in Mexico. Confirmed subpopulations are mainly distributed in center and southwestern areas. Northern registers should be confirmed.
Even while we do not have direct measurements of population extent and decline, because this mushroom is a highly valuable export, there are precise data on export volumes to Japan dating from 1989. Matsutaque exports from Mexico to Japan started in 1989 reaching 15000 kg. From 1993 to 1995 the productive populations in the country were found and intensively exploited reaching productivities of 25875 kg in 1993, 34681 kg in 1994, 55512 kg in 1995. After 1995 the natural production of T. mesoamericanum declined from 42318 kg in 1996 to 4435 kg in 2000 (Martínez-Carrera et al 2002). This dramatic productivity reduction is associated with higher average prices paid to rural gatherers (USD $ 32.11-55.21 per kg) by private companies, so it is not associated with a decline in the market. Martínez-Carrera et al 2012 discussed that these may indicate that the natural production of matsutake mushrooms is decreasing, and that it is perhaps being overexploited, despite strong official regulations (NOM-059-ECOL-1994, NOM-010-RECNAT-1996); or may also be due to unusually dry years, and even to forest logging, succession, or diseases (Martínez-Carrera et al 2002). However, in recent years the production was even lower, ranging from 921 kg in 2010, 2853 kg in 2011, 2853 kg in 2012, 1298 in 2012, 2501 kg in 2013, and 1809 kg in 2014 (INEGI 2011, 2012, 2013, 2014, 2015). Because the international price of the mushroom has not declined, and the demand stays stable, we assume that export volume is a good proxy for a clear population decline.
Population Trend: Deteriorating
Solitary to gregarious, often in complete or incomplete rings, in subtropical to montane (ca. 2000–3000 m) pine or mixed Pinus-Quercus forests subject to summer rainfall, with species such as Pinus teocote, P. douglasiana, P. patula accompanied by Quercus scytophylla, Q. crassifolia, Q. laurina, Q. rugosa, and Q. conzattii (Trudell et al 2017).
Tricholoma mesoamericanum has a large EOO and its known AOO and number of subpopulations are also large. Some of the subpopulations have disappeared due to logging and change in land cover use. However, the most important threat to this species is the extensive collection of young stages of the fruit body “buttons”. The negative effects of extensive collection are reinforced by the bad practice of racking the leaf litter in search for the mushroom buttons. This expose and kills the mycelia. So, this is one of the well documented cases where intensive collection of fruitbodies do have a negative impact on mushroom populations.
Bad collection practices (racking) should be eliminated thru local autoregulation and exploitation volumes should be regulated and monitored by regional and federal laws.
As a huge reduction in reproductive individuals is documented, research on recovery of populations is necessary.
All the American species of the T. matsutake complex (T. magnivelare, T. mesoamericanum and T. murrillianum) are included and exploited together with T. matsutake in the biocultural species “matsutake”. All the species within matsutake are threatened by the same economic interests and by the same bad recollection practice of raking the soil to expose young mushroom “buttons”. The buttons reach more than $500 US per kg in Japanese markets.
GBIF.org (22nd February 2018) GBIF Occurrence Download https://doi.org/10.15468/dl.6qnogy
INEGI. 2011. Anuario estadístico del comercio exterior de los Estados Unidos Mexicanos 2010: exportación en dólares. Instituto Nacional de Estadística y Geografía, México.
INEGI. 2012. Anuario estadístico del comercio exterior de los Estados Unidos Mexicanos 2011: exportación en dólares. Instituto Nacional de Estadística y Geografía, México.
INEGI. 2013. Anuario estadístico del comercio exterior de los Estados Unidos Mexicanos 2012: exportación en dólares. Instituto Nacional de Estadística y Geografía, México.
INEGI. 2014. Anuario estadístico del comercio exterior de los Estados Unidos Mexicanos 2013: exportación en dólares. Instituto Nacional de Estadística y Geografía, México.
INEGI. 2015. Anuario estadístico del comercio exterior de los Estados Unidos Mexicanos 2014: exportación en dólares. Instituto Nacional de Estadística y Geografía, México.
Martínez Carrera, D., Morales, P., Pellicer González, E., León, H., Aguilar, A., Ramírez, P., ... & Gómez, M. (2002). Studies on the traditional management, and processing of matsutake mushrooms in Oaxaca, Mexico. Micologia Aplicada International, 14(2).
Trudell, S. A., Xu, J., Saar, I., Justo, A., & Cifuentes, J. (2017). North American matsutake: names clarified and a new species described. Mycologia, 109(3), 379-390.