First person to use this name on MO: Danny Newman
Habitat and distribution. Solitary or gregarious in small groups, on red clay soil, in a mesophytic forest. Known only from the type locality.
Material examined. Mexico, Oaxaca, road Tux te-pec to Oaxaca, near to Llano Grande, July 20, 1980, J. Jacobs 199 (XAL); J. Jacobs 202 (holotype, XAL).
Discussion. Psilocybe oaxacana is close to P. chiapanensis Guzmán of the section Cordisporae (Guzmán, 1995), for the two types of cheilocystidia, however in P. chiapanensis the cheilocystidia type A are (10.5–) 12–16 (–17.5) × 5.5–6.5 µm, ventricose-rostrate or sublageniform, and the type B are (16–) 17–22.5 × 5–8 µm, ventricose or subfusoid, moreover that fungus has a papilla in the pileus. For the bulbous stipe P. oaxacana is close to P. subtropicalis Guzmán (Guzmán, 1995), but diﬀ ers in the form and size of the pleurocystidia and for the presence of only one type of cheilocystidia. The setae observed in the mycelium are uknown in P. chiapanensis; these setae are like those recently reported in P. guilartensis Guzmán, Tapia et Nieves-Rivera emend. Guzmán (Guzmán et al., 2003) from Puerto Rico, but that species presents pleurocystidia of two types, also two types of cheilocystidia, but both pleurocystidia and cheilocystidia diﬀerent of those in P. oaxacana.