The species should be listed as Vulnerable under the criteria A3c; B2ab(ii,iii,iv) since: due to global warming its population is projected to reduce significantly due to a decline in are of occupancy (AOO) of 41.5% in the next 50 years; it already occupies a restricted area of less than 1500 km2, its five known subpopulations are truly fragmented acting as “sky islands” and are probably genetically isolated, the decline of its area of occupancy is observed and projected due to area reduction, decrease of habitat quality and a reduction of subpopulations.

Psilocybe aztecorum is a mycenoid fungus, strongly hygrophanous, with a golden, yellowish-orange, yellowish-brown- to brownish-gray pileus that soon fades to milk white, with mycelial cords at the base of the stipe, and a sublignicolous to lignicolous habitat. It has the longest basidiospores within Psilocybe Sect. Aztecorum (10.4-) 12-14 (-17) μm (Guzmán 1978, 1983).
Psilocybe aztecorum var. aztecorum Heim emend. Guzmán is different from P. aztecorum var. bonetii (Guzmán) Guzmán (= P. bonetii Guzmán) in its longer basidiospores and habitat (Guzmán 1983).

NOTE The documentation of this assessment is being revised and edited when finalized when entered to IUCNs Red-List database. Psilocybe aztecorum was one of the main species used by Mesoamerican pre-Columbian civilizations as enteogenic mushrooms. It still is recollected for hallucinogenic purposes in the center of Mexico. This species is endemic to the center of the Transmexican Volcanic Belt. The habitat of this species is restricted to high mountain (above 3000 m a.s.l) Pinus hartwegii forests. As a consequence, its habitat represent “sky islands” wich are truly fragmented. These forests are the most imperiled temperate vegetation in Mexico due deforestation and climate change. This species should be protected because its biocultural importance, its restricted geographic range, and the severely endangered status of its habitat.

This species is restricted to the center of the Transmexican Volcanic Belt in the higher mountains of central Mexico from 3000 to 4000 m. These include the Nevado de Toluca volcano, the Chichinautzin mountain range, the Sierra Nevada mountain range (Popocatépetl, Iztaccíhuatl, and Tlaloc volcanoes), the Malinche volcano and Ajusco volcano.
Mexico: Puebla, State of Mexico, Tlaxcala and CDMX.

In the monograph of Psilocybe Guzmán (1983) listed 23 collections from 5 localities. GBIF (2018) list 12 observations of this species after 1980. All observations and register localities belong to the subpopulations of Nevado de Toluca volcano, the Chichinautzin mountain range, the Sierra Nevada mountain range and the Malinche volcano.
Guzmán (1983) assumed that it would be likely that this species could also grow in other high mountains of Mexico. However, even while it has been studied since 1957, no new localities outside the center of the Transmexican Volcanic Belt have been found. As a consequence we assume that the current known distribution of the species is very close to its whole natural range.
The total area covered by the habitat of this species is around 1400 km2, however it is deteriorating due to deforestation and global warming.

Gregarious in groups of 5-20 fruit bodies, sometimes fasciculate, sublignicolous or lignicolous, growing on soil with wood debris or on twigs or very rotten logs, rarely on pines cones, in open woods of Pinus hartwegii with abundant grasses such as Festuca tolucensis and Muhlenbergia quadridentata, and the herbaceous plant Alchemilla procumbens, at 3200-4000 m of elevation. Fruiting from August to October (Guzmán 1983).

Although Psilocybe mushrooms are common saprotrophs with relatively large ecological niches, P. aztecorum has a very restricted habitat limited to the higher elevations (3000-4000 m) of the tallest mountains of central Mexico (Guzmán 1983). Pinus hartwegii is endemic to those areas in the center and north of Mexico where it establishes monodominant alpine pine forests. Due to its adaptations to cold weather, P. hartwegii is the most imperiled pine species in Mexico when climate change scenarios are modeled. It is expected to reduce its potential habitat in 41.5% in the next 50 years. Particularly, the P. hartwegii subpopulations in the Transmexican Volcanic Belt, where P. aztecorum develops, are in high risk of extinction (Arriaga y Gómez 2004).
Additionally, P. aztecorum fruit bodies are harvested to be sold as recreational drugs in the center of Mexico. Since the traditional use of this fungi as entheogenic is almost lost, there are not social barriers to its exploitation.

Psilocybe aztecorum is included in the “Norma Oficial Mexicana NOM-059-Semarnat-2010”, which lists the Mexican species of animals, plants, and fungi under protection and their risk, under the “Threatened” category. However, this is not accompanied of any specific conservation action.
The tallest parts of the mountains in central Mexico are declared National Parks, though fires, plagues, illegal timber extraction, and cattle grazing are still frequent.
Given the dramatic projections on habitat reductions due to climate change, ex situ conservation actions should be taken as germ-plasm collections.

Pinus hartwegii populations in the north of Mexico should be examined carefully to determine weather P. aztecorum is really endemic to the Transmexican Volcanic Belt. Additionally, phylogenetic analysis are needed to determine if P. aztecorum var. aztecorum is really different from P. aztecorum var. bonetii which inhabits Pinus montezumae and Abies religiosa forests in the adjacent lower part of the habitat of P. aztecorum var. aztecorum (Guzmán 1983).

Psilocybe aztecorum was one of the main species used by Mesoamerican pre-Columbian civilizations as entheogenic mushrooms. It still is recollected for hallucinogenic purposes in the center of Mexico, where it is illegally sold as a recreational drug. As a consequence the extraction patterns, volumes, and market values are unknown. Unregulated strain traffic and illegal culture occurs.

Arriaga, L., & Gómez, L. (2004). Posibles efectos del cambio climático en algunos componentes de la biodiversidad de México. Cambio climático: una visión desde México, 253-263.

GBIF Occurrence Download doi:10.15468/dl.3ersr1 accessed via GBIF.org on 08 Feb 2018.

Guzmán, G. (1978). Variation, distribution, ethnomycological data and relationships of Psilocybe aztecorum, a Mexican hallucinogenic mushroom. Mycologia, 385-396.

Guzmán, G. (1983). The genus Psilocybe: a systematic revision of the known species including the history, distribution and chemistry of the hallucinogenic species(No. 74). J. Cramer.