Observation 285546: Psilocybe heimii Guzmán

Two unknown Psilocybe specimens collected on El Yunque Trail while searching for herbarium specimens of P. guilartensis. Growing together on clay bank along El Yunque Trail in El Yunque National Forest, Río Grande, PR. (Note there is a specimen of P. guilartensis in some of the photos, identified in the comments).

Species Lists


Specimens are on the two on the right. (Specimen on the left is most likely P. guilartensis)
Specimens are on the two on the right. (Specimen on the left is most likely P. guilartensis)
Specimens are the two above. The specimen below is P. guilartensis

Proposed Names

61% (2)
Recognized by sight: I think all three mushrooms are the same species, but in different stages of development. Alonso and I are also beginning to suspect that P. heimii is the oldest name for P. banderillensis and P. guilartensis. The difference between P. heimii and P. banderillensis/guilartensis is that the latter lacks pigmented pleurocystidia (pseudocystidia), but perhaps it’s sometimes rare or absent, and when people find it they call it P. heimii and when they don’t they call it P. banderillensis/guilartensis. DNA sequencing is needed to help sort these species out.
Used references: Alonso Cortez-Perez
28% (1)
Recognized by sight: Growing in the same habitat as previous collections of P. guilartensis.
Based on microscopic features: Spore measurements and traits were a match with the specimen strongly believed to be P. guilartensis.
46% (2)
Based on microscopic features: hyaline cystidia

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= Observer’s choice
= Current consensus


Add Comment
Yes, it is but…
By: Alan Rockefeller (Alan Rockefeller)
2020-07-04 21:20:35 CDT (-0500)

They don’t really have brown cystidia. It’s slightly grayish/yellowish at best, and this is the pseudocystidia, which isn’t mentioned until Guzman’s more recent papers. Section Cordisporae is correct, though the sections, sensu Guzman are all messed up and don’t reflect actual phylogeny in most cases.

By this section
By: kurt miller (komille277)
2020-06-30 19:29:26 CDT (-0500)

You mean Sect. Brunneocystidiatae? Help me understand this because is that not latin for brown cystidia? Also MO has banderillensis listed under Psilocybe sect. Brunneocystidiatae and Psilocybe sect. Cordisporae. Which one is it?

P. guilartensis doesn’t really have pigmented cystidia
By: Alan Rockefeller (Alan Rockefeller)
2020-06-30 16:03:35 CDT (-0500)

None of the species in this section do. Guzman said all sorts of things have pigmented cystidia that don’t really.

What you should look at is pleurocystidia and cheilocystidia – how many types of each? Are there clusters of large, cylindrical cheilocystidia, or are they all thin with long necks? Are all of the pleurocystidia small, or are there some large and some small?

By: kurt miller (komille277)
2020-06-30 14:20:14 CDT (-0500)

In “New species of Psilocybe in the Caribbean, with an emendation of
P. guilartensis” pigmented cystidia is present in P. guilartensis, presumably in all 20 specimens listed under ‘material examined’. This collection which lacks pigmented pleurocystidia would not be consistent with those collections, or is maybe a rare unpigmented variety of ‘guilartensis’ (the discussion of ‘banderillensis’ vs. ‘heimii’ being apt)

By: Alan Rockefeller (Alan Rockefeller)
2017-08-08 14:50:46 CDT (-0500)

What size are the pleurocystidia? Are they all the same shape/size, or do they seem to fall into two types – one small and bottle shaped and the other larger and more refractive?

By: kurt miller (komille277)
2017-08-08 13:22:46 CDT (-0500)

Jean and I looked at them under the microscope and they do lack pigment in the pleurocystidia. Also, the other micro characters of the two collections seems to indicate they are the same species. -Kurt