Pileus (Cap): 20-26 mm in diam, subconvex to subcampanulate, subpapillate, sublubricous to dry, glabrous, even to striate toward the margin, reddish brown to brown, hygrophanous, fading to straw colour, staining dark blue to blackish when moist, almost black when dry mainly toward the margin.
Lamellae (Gills): adnate or adnexed, pale brown to cinnamon brown or blackish violet, with whitish edges. Stipe (Stem): 40-80 x 1-3 mm, cylindric, whitish to concolourous with the pileus, hollow, caerulescent, covered with floccose appressed white fibrils, with a subbulbous hollow base, up to 10 mm in diam in dry, without pseudorhiza. Veil absent in the adult. Context whitish, fleshy in the pileus, subfleshy in the stipe, staining blue when cut.
Microscopic features: Spores (5.5-)6.5-7(-8) x 5-5.5(-6) x 4-5.5 um, subrhomboid in face view, subellipsoid in side view, with a thick wall (up to 1.5 um thick), brownish yellow, with a broad germ pore at one end and an acute short appendage at the distal end.- Basidia 17.5-26.5 x 5.5-8 um, 4- spored, clavate or subcylindric, hyaline.- Pleurocystidi a (12-)13-21(-22.5) x (4-)5-6(-7) um, ventricose subacuminate or ventricose rostrate, hyaline, more or less common.- Cheilocystidi a (16-)20-28(-32)(-42) x 5-6.5(-7) um, ventricose or subcylindric, irregularly branching mainly at the top, hyaline, abundant.- Subhymenium formed by subglobose elements, 3- 4.8 um diam, hyaline or yellowish.- Gill trama regular, formed by hydine thin-walled hyphae, 3.2-24 um wide.- Epicutis subgelatinized, formed by108 Guunan, Psilocybe hydine repent hyphae 2.4-4 um wide.- Hypdermium with subglobose elements mixed with hyphae 3-12 um in diam, hyaline or incrusted with brown yellowish pigment.-Clamp connections present.
Season: June through November.
Habitat and Distribution: Found on soil, in open places of subtropical (mesophytic) forests. Known from Guatemala and Mexico
Similar Species: Psilocybe herrerae Is a close taxon, but differs in the more branched cheilocystidia and thicker pleurocystidia (6-9um), and in the presence of pseudorhiza (Guzman, 1983).
Other Notes: Due to the form and size of the spores, this species belongs to Sect. Cordispora. P. subtropicalis is widely distributed in subtropical forests. Psilocybe mexicana grows also in the same Guatemaltecan locdity.