Host-Substratum/Locality: On soil in meadow in Pinus-Quercus forest: México State
Psilocybe castillotovarii belongs to section Singerianae Guzmán 1, for their subellipsoid thin-walled spores and lack of bluing of its basidioma. The form and size of the pleurocystidia and cheilocystidia defined the species.
Pileus 20-25 mm diam, convex to plane, smooth, pale yellowish brown, subhygrophanous. Lamellae subadnexed, dark violaceous brown, edges concolorous.
Stipe 35-40 × 1-2 mm, equal, hollow, reddish yellow brown, scantily covered by whitish fibrils. Veil poor developed.
Context pale brown, pliant.
Odor and taste fungoid.
Basidiomata not bluing.
Spores (7-) 8-9 (-9.5) x (4-) 4.5-5.5 (-6) μm, subellipsoid, both in face- and side-view, thin-walled, yellowish brown, with a distinct and broad germ pore on one end and with an apical short appendage in the other. Basidia 16-25 × 7-8 μm, 4-spored, hyaline, ventricose or subclavate, with a median constriction. Pleurocystidia (30- ) 43-53 (-60) x (8-) 11-17 μm, scarse to common, hyaline, ventricose-rostrate with a thick and short neck, sometimes sublageniform with a narrow base. Cheilocystidia (22-) 35-55 × 10-14 (-16) μm, hyaline, same form and variation as the pleurocystidia, in a fertile margin of the lamellae. Subhymenium subcellular, with hyaline elements, 10-15 μm broad, incrusted with brownish pigment. Hymenophoral trama regular, with hyaline hyphae, 4-10 (-17) μm broad, more or less incrusted with a brownish pigment. Pileipellis subgelatinized, with hyaline, postrate, thin hyphae. Subpellis (hypodermium) with hyaline hyphae, 3-6 μm broad. Context with hyaline hyphae, 3-11 μm broad, yellowish in mass. Clamp connections present.
Habitat and distribution. Gregarious on soil, in a meadow in a Pinus-Quercus forest, at 2800 m elev. Known only from the type locality.