These were growing on a dead log, had pink spores, and free gills. They seem to match the sparse descriptions in Mushrooms Demystified and a couple of other sources.


Proposed Names

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Used references: Phytotaxa 180 “Molecular phylogeny and phylogeography,of holartic species of Pluteus section Pluteus” Alfredo Justo 2014.

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By: Davide Puddu (Davide Puddu)
2015-03-23 12:04:41 CDT (-0400)

never seen or heard of this species,amazing!

so much for …
By: Debbie Viess (amanitarita)
2015-03-23 12:01:43 CDT (-0400)

the “borealis” part of the name! ;)

Thanks Fredo….Pluteus leucoborealis is perhaps a better possibility.
By: Ron Pastorino (Ronpast)
2015-03-21 18:29:55 CDT (-0400)
the spores and other characters match fairly well. I believe there was some Alder in the area so that is a positive.
By: Alfredo Justo (Fredo)
2015-03-21 00:21:45 CDT (-0400)

Pluteus nothopellitus (as defined by the type) is younger a synonym of Pluteus hongoi, a species that is widespread in Eastern North American and Eurasia, but as far as we can tell does not occur in Western North American.

With no clamps on the pileipellis and ocurring on hardwoods there are limited number of possibilities. The spore size you give does not fit well with Pluteus petasatus. Could be an albino form of Pluteus exilis or Pluteus cervinus(more unlikely). You can also compare it closely with the description of Pluteus leucoborealis here:

Since the original description this species has been already found in Portland (Oregon; and we do not really know how far south it extends on the West Coast

The area I was in consisted mostly of hardwoods,
By: Ron Pastorino (Ronpast)
2015-03-20 19:54:18 CDT (-0400)
and very few conifers.

Slight advantage for P. nothopellitus.

I know it’s a long shot…
By: Christian (Christian Schwarz)
2015-03-20 19:43:42 CDT (-0400)

but do you remember if it was on hardwood or conifer?

Could be!
By: Ron Pastorino (Ronpast)
2015-03-20 19:42:19 CDT (-0400)
By: Christian (Christian Schwarz)
2015-03-20 19:11:59 CDT (-0400)

Closest record of P. nothopellitus is one from Michigan.
Justo et al report the spores as: 7.3-8.0 × 5.1-5.8 μm ( a bit narrower than yours) and clamps lacking.

A preliminary match?

You may be right Christian.
By: Ron Pastorino (Ronpast)
2015-03-20 18:55:20 CDT (-0400)

I still had this collection so I decided to do some additional microscopy.
Spores ~ 6.8-8.1 X 5.3-7.1 microns, mostly broadly ellipsoid.
Q(range) = 1.11-1.35
Q(avg)= 1.23
Pleurocystidia abundant, ~ 74-100 X 11-25 microns, fusiform with horns.
Could not see any clamp connections on the cap hyphae.

Revisiting this
By: Christian (Christian Schwarz)
2015-03-20 12:14:31 CDT (-0400)

I think maybe an albino form of one of the more frequent species should be considered

Will Do.
By: Ron Pastorino (Ronpast)
2007-11-29 21:29:18 CST (-0500)

I’m drying them and will see Else this weekend at the Fungus Fair.

Haven’t seen these
By: Douglas Smith (douglas)
2007-11-29 18:17:45 CST (-0500)

You should maybe save these, and let Dr. Else Vellinga know about them. I think she is collecting data on Pluteus in CA.