Amanita tuza is an edible fungi with infrequent fruiting in high coniferous mountain temperate forest of central Mexico. It is a big easily recognizable and conspicuous fungus, so its scarce registers are not due to under-sampling.
Its subpopulations are scattered and are fragmented. Over harvesting and climate change are mayor threats to its population and habitat. Within the next 50 years its habitat will reduce at least 50%.
The species should be listed as Vulnerable under the criteria A3c: due to global warming, its population is projected to reduce significantly due to a decline in are of occupancy (AOO) of at least 50% in the next 50 years. Its ten known subpopulations are truly fragmented acting as “sky islands” and are genetically isolated, the decline of its habitat is observed and projected due to area reduction, decrease of habitat quality and a reduction of subpopulations.
This species is characterized by its subhypogeous growth, which removes the soil like the pocket gopher (Guzmán 1975). The sporocarp almost completes its development under the surface of the soil, but when it is mature it suddenly emerges raising the soil with it. Amanita tuza has a white to yellowish gray pileus, viscid, smooth, margin slightly sulcate, non apediculate, with a thick, white, calyptrate remnant of the volva, sometimes divided into two or more pieces (Guzmán, 1975). Usually with no yellow tint at maturity (Tulloss, 2009). Lamellae with floccose edges, subadnate to free. Stipe subbulbous or fusiform. Annulus white, pendant and apical, membranous, persistent, more or less thick, striate at the upper side, smooth at the inner side. This species is close to A. calyptratoides and A. lactea, from whose it differs in the size of the spores. In addition the pileus color in A. calyptratoides is yellow-greenish to brownish orange. Amanita tuza corresponds with the fungus that Singer (1957) and Herrera & Guzmán (1961) considered as A. calyptratoides and A. calyptroderma, respectively.
NOTE The documentation of this assessment is being revised and edited when finalized when entered to IUCNs Red-List database. Amanita tuza was reported for the first time in Mexico (Guzmán, 1975), and since then there have been few more records. This is an edible fungus in coniferous high mountain forests of Mexico, which is occasionally sold in popular markets. It is also an ectomycorrhizal fungus, associated with different hosts including pines and firs. These forests are the most imperiled temperate forests in Mexico due deforestation and climate change. This species should be protected because of its limited distribution to the center of Mexico, and also because it is an edible fungus that should be taken into account in forests management of non-woody resources.
Amanita tuza grows in high mountain conifer forests mainly in central and occasionally in southwest Mexico. The southern record comes from Sierra de Juarez, Oaxaca. It also has records from Sierra de Quila, Jalisco state, and in Colima Volcano in Colima state. From Queretaro state is also registered in Sierra Gorda and Michoacan state. Near Nevado de Toluca volcano, in Estado de Mexico. In Ajusco volcano in CDMX and also in Sierra Nevada. It is also distributed in La Malinche, Tlaxcala, and in Cofre de Perote, Veracruz.
There is a record of a doubtful subpopulation near Yecora in the frontier between Sonora state and Chihuahua close to Yecora–La Colorada highway. Confirmed subpopulations: Two subpopulations from Sierra de Quila, Jalisco state. One subpopulation at piedmont of Colima volcano. One near Tonatico, Pinal de Amoles municipality, in Sierra Gorda, Queretaro state. One in Hidalgo municipality, in Michoacan. One subpopulation from Estado de México, near Amanalco in the volcanic range of Nevado de Toluca. Another subpopulation at Ajusco volcano, CDMX. One subpopulation from Sierra Nevada, at Iztaccíhuatl and Popocatépetl volcanos. In Tlaxcala state, particularly in La Malinche volcano, there is another subpopulation. Near Cofre de Perote, Veracruz also exists a subpopulation. The most southern subpopulation is registered near Cerro Yatin in Oaxaca state, near Cuajimoloyas in Sierra de Juarez (GBIF, 2018). One more record comes from San Andres Huayacatitla, in Puebla state (Pellicer-González et al., 2002).
Population Trend: Stable
Growing disperse from one another and often with solitary habit, in coniferous high mountain (Abies and Pinus) forests. Amanita tuza sporcarps have a subhypogeous growth and almost completes its development under the surface (Guzmán, 1975). It can fruit from June to August and extend its fruiting season until September according to Burrola-Aguilar et al. (2013). It grows at an altitudinal range from 2500 to 3300 m. Montoya et al. (2003). It is reported that A. tuza grows outside the forests, in open areas, even when this is reported as an ectomycorrhizal species.
Amanita tuza is an edible species eaten by local people at states like Tlaxcala, Hidalgo and Estado de México, it is used as food or trade during rainy season. Some of the major threats are its limited distribution to high altitude forests in the Transmexican Volcanic Belt (where most of its records belong) and its scarce fruit-body production. Over-harvesting could represent a threat for the species. even when the majority of populations are distributed at higher altitudes, which are considered as National Parks, it is frequent that those sites are under illegal timber extraction and climate change that affects A. tuza hosts.
Climate change is also a mayor threat for A. tuza population. Since global warming is affecting dramatically alpine ecosistems, P. montezumae, P. harwegii and Abies religiosa forests are going to reduce its potential habitat around 50% in the next 50 years (Arriaga and Gómez 2004; Sáenz-Romero et al. 2012).
Some of the sites where Amanita tuza distributes are considered in National Parks territories where Pine forests are constantly under illegal timber extraction pressures. Some of the major conservation actions should include local people´s knowledge and uses of the species, as it represents an important resource in the rainy season.
One of the main needs is an increase in sampling effort, to elucidate if its actual distribution is constrained by the absence of records, or if it represents the natural distribution range of the species; particularly it is necesary to confirm those reported populations outside the Transmexican Volcanic belt. Also, phylogenetic analysis including species considered close to A. tuza like A. calyptroderma should be incorporated in order to understand their phylogenetic relationships and to know if some described collections are currently misidentified. This species, as reported by Montoya et al. (2003), grows outside the forests, and often in open areas; so an important issue for research, is the functional guild of A. tuza, considering that some species of this genus like A. thiersii are saprotrophic. Stable isotopes data should be incorporated in the studies of this species.
This is an edible species whose trade occurs in some states in the central part of Mexico, including Hidalgo and Tlaxcala.
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