Observation 80923: Pluteus orestes Vellinga & Justo
When: 2011-10-19
Herbarium specimen reported

Notes: These were found by Patty Reifers.
They were growing on an conifer stump at ~ 6400 ft.
Spores were fairly large, ~ 9.1-11.0 X 7.1-8.2 microns.
The gill cystidia was ~ 70-90 X 20-25 microns. The horns on the cystidia seemed to be only two pronged.
They do look similar to P. cervinus but the spores are much larger. Haven’t been able to find another likely candidate.

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Thanks Fredo. I was beginning to doubt
By: Ron Pastorino (Ronpast)
2011-11-05 00:15:25 CET (+0100)

my microscope numbers.
Look forward to learning what you find out.

spore size
By: Alfredo Justo (Fredo)
2011-11-04 21:11:38 CET (+0100)


Your measurements for the spores were totally accurate, the spores are fairly large 8.5-11 × 6.5-8 µm, on average they are 9.8 × 7.3 µm Basidia are 4-spored, so this is not caused by the presence of 2-spored basidia

It has very abundant clamp-connections, and cheilocystidia that can be very long (up to 110 µm). Morphologically the most similar thing is the European Pluteus primus, but the spore size does not fit that taxon. Very probably is one of the species in the cervinus group with clamps but at present the delimitation of these taxa (P. pouzarianus, P. primus, P. brunneidiscus, P. subcervinus, and some more) is still very problematic.

This will go for the DNA sequencer soon and we’ll have a better of its identity!

By: Alfredo Justo (Fredo)
2011-10-31 14:14:36 CET (+0100)

Hi Ron,

I’d definitely take a look at the specimens if you can send them over (thanks!)

Drew, yes the spore size is on the upper range even for P. salicinus, but occasionally this species can have average lengths of 9 to 9.5 µm. Still, I do not think this is anything in the salicinus group.

Since I’ve about reached the limits of my Pluteaceae
By: Ron Pastorino (Ronpast)
2011-10-29 02:30:30 CEST (+0200)

ID capabilities, I’d would be happy to send the voucher to anyone who wishes to examine them further.

spore size
By: Drew Parker (mycotrope)
2011-10-29 00:44:31 CEST (+0200)

I agree it does not look like P. salicinus, but even it’s spores, according to Vellinga in Flora Agaricina Neerlandica, are mostly 7.0-9.5 though occasionally as small as 6.5 or as large as 12. Banerjee lists them at 7-8.4(10). In the micrograph here most appear to be about 10 µm long. Can’t find any Pluteus that average even close to that, and obviously this is a Pluteus in section Pluteus.

interesting Pluteus
By: Alfredo Justo (Fredo)
2011-10-29 00:02:55 CEST (+0200)

Hi Ron,

Spore size is larger than what is usual for P. cervinus. The only species in sect. Pluteus that I’m familiar with and that can reach that spore range is P. salicinus but your specimens do not look like P. salicinus at all.

You should look for clamp-connections (specially at the base of cheilocystidia and on the pileipellis) and also check shape and size of the cheilocystidia. That may give us more clues to identify this.


Very odd
By: Drew Parker (mycotrope)
2011-10-28 22:50:18 CEST (+0200)

After a fairly exhaustive literature search, I failed to find any Pluteus with spores in this range. Everything seems to be between 5 – 9.5 in length. I would like to hear Else’s take on this.

Created: 2011-10-28 21:38:56 CEST (+0200)
Last modified: 2015-01-11 08:18:09 CET (+0100)
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