Observation 56433: Suillus flavidus (Fr.) J. Presl
When: 2010-10-19
Herbarium specimen reported

Notes: These could be called Suillus umbonatus and apparently there has been some attempt to synonymize these two names.
However, based on the descriptions, one can see some subtle differences, particularly in the spores.
These spores were definitely not olive brown as noted in Thiers.(see photo of spore print). The Bessette book notes that S. flavidus has “dull cinnamon” spores. Also, Thiers notes that the spores of S. umbonatus are “obscurely ventricose in side view”. The S. flavidus has smooth spores according to Bessette. These do look smooth.
The spores were ~ 8.0-10.0 X 3.8-4.3 microns which fits both species.
Not much to go on for a definitive differentiation but good enough for me…for now.

Proposed Names

86% (1)
Eye3 Eyes3
Used references: North American Boletes by Alan Bessette, Willian Roody, and Arleen Bessette
California Mushrooms by Harry Thiers

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Eye3 = Observer’s choice
Eyes3 = Current consensus

Comments

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I agree
By: Irene Andersson (irenea)
2010-10-24 16:37:05 CDT (-0400)

Most Suillus species seem to be host specific, and I beleive that more work needs to be done with these.

Thanks Irene for the clarification
By: Ron Pastorino (Ronpast)
2010-10-24 11:57:01 CDT (-0400)
These did have a somewhat different look than the S. umbonatus that we commonly find in the coastal forests, which are normally smaller and more delicate. Thiers description of S. umbonatus does mention that S. umbonatus is found both among Bishop pine mixed with hardwoods along the California coast as well as in the Sierra Nevada and Cascade ranges along with lodgepole pine, fir and alder.

He lists material studied from both areas.
It would be interesting to see specific DNA work comparing material from the different geographical and host sites.

Delicate topic
By: Irene Andersson (irenea)
2010-10-24 09:31:04 CDT (-0400)

I have always seen them with the same cap colour as yours, and gladly accepted that umbonatus and flavidus were synonyms, but when I ran into a big colony of bright yellow ones (obs 13726), I started to wonder if it didn’t exist different species, or at least forms, after all.
S. umbonatus is described from North America, and S. flavidus from Europe, but there’s no evidence for or against that both can occur on both continents.

I have found DNA-sequences of ‘umbonatus’ from USA, and ‘flavidus’ from Canada and Scotland. The parts of the sequences that I could compare, show no difference between the USA and Canada collections, and they were only 2 pairs different from the scottish. In other papers, I have seen that with 1% difference, they have taken for granted that these two are the same species.

But, I ask myself everytime I read results like this – what have they actually been running sequences from? What do we know about the identification of the collections? Have they been ID:d by different books, different interpretations of the species? Couldn’t there still be two (or more) different species, if only one has been sequenced so far?
If the sequences aren’t followed by thorough descriptions and pictures, how will we ever know?

btw, my translation of ‘obscurely ventricose’ is ‘slightly swollen’ (usually on one side), they can still be smooth..

Created: 2010-10-24 00:27:19 CDT (-0400)
Last modified: 2010-10-24 00:38:23 CDT (-0400)
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