Observation 33835: Boletus subtomentosus L.
When: 2006-09-05
No herbarium specimen

Notes: Under oaks. Checking the MO archives we either have a very variable species or several misidentifications. I will be interested in the group’s opinions.

[admin – Sat Aug 14 01:59:15 +0000 2010]: Changed location name from ‘Centennial. Park, Salem, Oh.’ to ‘Centennial Park, Salem, Ohio, USA

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Boletus tenax
By: walt sturgeon (Mycowalt)
2010-02-21 11:49:18 PST (-0800)

is infrequent locally in my experience. As I recall it has white to cream flesh. Bessette and Roody state that the flesh turns slowly reddish purple when exposed.

Synonyms
By: Irene Andersson (irenea)
2010-02-21 01:31:26 PST (-0800)

Yes, it looks like spadiceus is a younger synonym of ferrugineus.

Xerocomus illudens/tenax (I found pictures at mushroomexpert) and the recently descibed european species X. chrysonemus do look like sister species. Mycelium and flesh is described to have a strong yellow colour in chrysonemus. What’s it like in tenax?

I can still imagine large difficulties with this group of species:
where to draw the line between them, not being able to identify them without extensive investigations with the microscope, and the lack of complete keys.
Shape, discoloration and reticulation on stem, and cap colour, aren’t very useful characters in a key. Habitat might be, once we have learned which ones we actually have with pine, oak, birch, etc.

Irene, Xerocomus confusion
By: walt sturgeon (Mycowalt)
2010-02-20 13:39:58 PST (-0800)

http://www.biodiversidadvirtual.com/...

This looks like Boletus tenax to me.

Also is Xerocomus ferrugineus a synonym of Boletus spadiceus?

Yes, Noah
By: Irene Andersson (irenea)
2010-02-20 12:50:16 PST (-0800)

There is no doubt that most, if not all, of us have chosen to treat them as subtomentosus in a wide sense, for some very good reasons; the large difficulties to get an ID without a microscope, and of course because we didn’t have good keys to different species.

You may find this paper interesting:
http://www.sciencebuff.org/...
Look particularly at the american collections – how they were ID:d initially, and how they form separate clades close to X. ferrugineus (the californian collection a clade of its own). Check also habitats for these collections.

Of course we can still treat them as subtomentosus s.l., but I find it interesting that different geographic distribution and habitats has created this “speciation”.

-
By: Noah Siegel (Noah)
2010-02-20 07:10:02 PST (-0800)

This is what I call subtomentosus, a northern conifer associate often fruiting late in the season.
http://www.mycoquebec.org/...

Thanks Irene.
By: walt sturgeon (Mycowalt)
2010-02-20 06:51:06 PST (-0800)
One key feature in subtomentosus
By: Irene Andersson (irenea)
2010-02-20 05:42:41 PST (-0800)

is bright golden yellow pores, but the cap colour can vary a lot according to the descriptions. I don’t think you can take for granted that this european species occur in USA at all. Some collections have been compared to the european ones and a couple of taxon found, that were close to ferrugineus.
Here you can find some european species (only a few, but excellent photos):
http://www.mtsn.tn.it/bresadola/gallery_index.asp

Created: 2010-02-19 15:24:28 PST (-0800)
Last modified: 2011-01-11 16:03:03 PST (-0800)
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