Observation 322376: Xerocomellus Šutara

One of our club member found it under oak and birch at a side of a rock wall.
Cap 4 cm in diameter, grayish brown, somewhat velvety.
Cap margin is reddish.
Pore surface is bright yellow, very slowly stain bluish brown.
Stipe is 5 cm long and 1 cm wide, somewhat tapering down to the base, with reddish punctae and striations over a yellow base color.
Yellow basal mycelium.
Taste pleasant or not distinctive.
Flesh staining blue very slowly from the base towards the cap and fade out. Photos about 5 minutes a part.
Will send it to DNA sequence.

Species Lists


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Copyright © 2018 I. G. Safonov (IGSafonov)
GenBank TEF-1 phylogram of BLASTn hits

Proposed Names

28% (1)
Recognized by sight
61% (2)
Recognized by sight
Based on chemical features: TEF-1 sequence — see the comment & phylogram below

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= Observer’s choice
= Current consensus


Add Comment
By: I. G. Safonov (IGSafonov)
2018-11-13 15:25:11 EST (-0500)

Yes, it’s a bona fide Xerocomellus sp., but not X. cisalpinus.
We need more TEF-1 sequences of taxa from that genus, particularly from North America, and a better software (e.g., MEGA 7) to analyze the data in order to get a better understanding of the evolutionary relationships. On second thought, there are probably many more ITS accessions of “domestic” Xerocomellus already in GenBank, so sequencing that locus is probably the way to go to achieve the desired result.

So to translate (please correct as needed)…
By: Scott Pavelle (Scott Pavelle)
2018-11-13 13:19:21 EST (-0500)

This is a Xerocomellus. One could argue it is the European species cisalpinus but it is more likely a new genetic species in a group that we know to be growing from the consistent set of new species out west.

Have I got that right?

DNA results discussion
By: I. G. Safonov (IGSafonov)
2018-11-12 11:49:38 EST (-0500)

A clean and contiguous TEF-1 sequence of 1144 bps was obtained from this material. There are no ambiguous characters. This stretch of the locus is between the 983F and 2218R primers, which were seen but edited out. Typically, shorter fragments of the gene – specifically the region between and including the 983F and 1567R primers that is on average 607-611 bps long – are sufficient for BLASTn-ing, but there exist a fair number of longer TEFs in GenBank.

A BLASTn search of the entire sequence returned Xerocomellus accessions as the top 7 hits (88-100% query cover and 93-98% similarity).
A BLASTn of the first 588 bps (the region between the 983F and 1567R primers sans the first primer) gave a similar profile, except that now 13 out of the 14 top hits were Xerocomellus accessions (94-100% query cover, 93-98% similarity).
A third BLASTn targeting specifically Xerocomellus accessions produced only 23 TEF-1 records labeled as such in GenBank, of which only 3 are from North America. However, analysis of these data revealed that not all accessions are bona fide Xerocomellus — see the discussion below.

A phylogram was built in GenBank, using a number of hits from the second BLASTn, and uploaded to this post. It consists of 22 out of the aforementioned 23 Xerocomellus assessions as well as 11 additional sequences belonging to taxa from the subfamily Boletoideae, where Xerocomellus happens to reside as per Wu et al. (2014, 2016). A Caloboletus accession was used as the outgroup.
Surprisingly, Xerocomellus got split into two “clades”. The top one contained a sequence from the holotype of Hortiboletus amygdalinus (highlighted in green). Suspecting that something was amiss, I cross-referenced the four HKAS accessions (Chinese collections) in that grouping with Wu et al. (2016) and confirmed them to clade in Hortiboletus. Unfortunately, the authors of these accessions had forgotten to edit their GenBank records accordingly.

The best match for MO322376 (98% similarity) is accessions of the European Xerocomellus cisalpinus. Indeed, the phylogram shows this taxon to be the closest relative (so far) of Robert’s collection.

I’d certainly call it a Xerocomellus
By: Christian (Christian Schwarz)
2018-07-12 23:05:31 EDT (-0400)
I believe the bicolors are…
By: Scott Pavelle (Scott Pavelle)
2018-07-09 15:30:21 EDT (-0400)

…getting either five or six loci tested.

By: Robert(the 3 foragers) (the3foragers)
2018-07-09 13:53:21 EDT (-0400)

Caloboletus did not even cross my mind. Definitely not in Caloboletus..
Unfortunately I was not the finder and the light condition where not ideal to take good photos and I did not want to wait with the photos till I got home.
For the DNA I want to do more then just ITS.

If this tasted bitter…
By: Scott Pavelle (Scott Pavelle)
2018-07-09 11:04:32 EDT (-0400)

…would you default to Caloboletus? I would have considered that based on the photos alone. How often do you run across one that has no, or a subtle, bitterness? I have found felleus that didn’t immediately trigger the bitter receptors though I have no doubt they would have done so if cooked.

This looks “bicolor-ish” enough to submit in the current study
By: Scott Pavelle (Scott Pavelle)
2018-07-09 11:00:24 EDT (-0400)

I would not hesitate to include it if you are happy with the number of photos and testing details.

Sure ,but…
By: I. G. Safonov (IGSafonov)
2018-07-08 18:05:03 EDT (-0400)

Can anyone really identify intermedius to a certainty, the kind of certainty we typically associate with a number of well-known taxa, e.g., T. plumbeoviolaceus or H. chromapes?
Sequencing/barcoding this collection is a good idea, especially if other intermedius suspects are to be sequenced later. You will probably get ITS, but you will need a protein-coding gene for a more confident generic placement. There are no sequences of any kind labeled as Boletellus/Xerocomellus intermedius in GenBank. It’s possible that Renee had her personal collection sequenced and maybe it even got published in GB, where it’s likely hiding under some generic name typical of all Canadian deposits, such as ‘Boletus sp. RL1234’. Oh, and I just remembered another possible resource: I gave Dr. Kudzma our 2016 COMA collection, obs 256649. I am pretty sure Linas sequenced it because he had some kind of collaboration going at the time with a researcher (not Roy Halling though) interested in North American Boletelellus.

By: Robert(the 3 foragers) (the3foragers)
2018-07-08 16:49:23 EDT (-0400)

We had that in mind as well, but what we find here is not like these one at all.
And the pores are not exactly xerocomoid.

Created: 2018-07-08 15:18:54 EDT (-0400)
Last modified: 2019-07-03 23:10:03 EDT (-0400)
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