Psilocybe thaiaerugineomaculans is a species of psilocybin mushroom first described as new to science in 2012 by renown Mexican mycologist Gaston Guzmán and his colleagues.
Found growing in cow dung in the Chiang Mai University Park in Thailand, this tropical coprophilous mushroom is to this day quite an enigma.
Because of certain morphological features such as the annulus on the stipe and its thick-walled spores, P. thaiaerugineomaculans was placed in section Stuntzae of the Psilocybe genus.

Guzmán believes that a picture of P. thaiaerugineomaculans is featured in Paul Stamets’ book “Psilocybin Mushroom of the World” at page 171 entitled “Mysterious, unidentified Psilocybes”. If that is the case, it has a white stem with a strong blue-green hue when bruised, similar to Psilocybe stunzii (aka Blue Ringer and Blue Legs) which could explain its epithet that contains the Latin root “aeru– “ meaning “blue-green”.
By its epithet, we can also deduct that P. thaiaerugineomaculans is a close relative to Psilocybe aerugineomaculans and P. subaeruginascens. As you may have noticed, our investigation leads us to add clues as we go.

The epithet is often the best clue offered and we notice another similarity with Inocybe aeruginascens.  Could it mean that Psilocybe aerugineomaculans contains the rare aeruginascin compound? The latter is analog to psilocybin and is closely related to the frog skin toxin bufotenine (5-HTQ), a potent 5-HT3 receptor agonist. This compound, identified by chemist and mycologist Jochen Gartz in the eighties, is believed to be the equivalent of what CBD is to THC.

Unfortunately, data on this exotic Psilocybe is rare, but maybe its spores have already made it to the world of in-vitro mushroom manipulation.


Visual Description

• Cap: 10–20 mm broad. Conic to sub-umbonate, finally convex. Margin is smooth, with striate when dry. Cap is hygrophanous, dark reddish brown to pale yellowish brown to whitish. Blackish chocolate when dry. Flesh bruises bluish. • Gills: attachment adnate to subadnexed, broad. Coloration brownish violaceous to chocolate-brown, with white edges. • Stem: 25–45 mm long by 3–4 mm thick. Surface smooth above, sub-floccose below, base with fibrillose. Coloration pale yellowish brown to white or brownish black to reddish brown. Hollow with mycelium at base. Annulus membranous, white to off white, thick, persistent. Turning bluish. • Microscopic features: 9–12 × 7–8(–9) × 5.5–7 μm • Taste and odor: taste strongly pungent after some minutes.


No official data was found, please let us know if you have some.

Habitat Origin

Solitary or gregarious at 300 m on soil with rotting cow dung, in an open grassland below the shadow of trees. Known only from this locality: Chiang Mai, Thailand.


The psychotronic fungal species in Thailand, as in most tropical countries, are poorly known, a drastic contrast to the richness of the mycoflora. With considerable destruction of tropical habitats, many species will likely disappear before being documented.