Observation 244148: Boletus pallidus Frost (Site ID) (Imleria pallida)

A solitary specimen in grass under mature (45-year-old) Pin Oak tree in suburban landscape. Unfortunately this specimen was very dry when I found it, and I was not able to get a spore print or any reaction to chemicals. Cap: 8.1 cm., dry smooth like fine kid leather. Stipe: 9 cm. X 3 cm. at widest point, narrower at apex, fibrous/woody. Tubes: 6 mm.; context 1.7 cm. at thickest point. Photos show the coarse reticulation on stipe, the rimose cap surface, and the purplish discoloration within the stipe flesh.

Species Lists


Copyright © 2016 Judi Thomas
Copyright © 2016 Judi Thomas
Copyright © 2016 Judi Thomas
Copyright © 2016 Judi Thomas
Copyright © 2016 Judi Thomas
Copyright © 2016 Judi Thomas
Copyright © 2016 Judi Thomas

Proposed Names

-26% (2)
Recognized by sight
30% (2)
Recognized by sight
-5% (3)
Recognized by sight
Used references: NAB
-12% (2)
Recognized by sight
84% (1)
Recognized by sight: Gestalt morphology
Based on chemical features: nrITS and nrLSU sequences

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= Observer’s choice
= Current consensus


Add Comment
Hello, Judy!
By: I. G. Safonov (IGSafonov)
2017-01-06 11:56:53 IST (+0530)

Thank you for your kind and generous comment. In all the honesty, I cannot take an iota of the credit for doing the work in procuring any of the DNA sequences I post to MO. The kudos, naturally, go the professional scientists with the know-how behind the scene. All I can say is that I am very grateful for the opportunity to make small, yet valuable, contributions to citizen science. I am glad these results brightened your day, too. :-)
Judy, I think that your curious-looking bolete turned out to be a surprise to everyone who had been following your observations and posted alternate ID proposals. However, even with the current molecular data serving as the proverbial “preponderance of the evidence”, it is still possible to make an argument against your aberrant Boletus pallidus being the true Pallid Bolete. For instance, one can play the morphology card and point out that the sequenced genes are not relevant to the observed phenotype. Be that as it may, your bolete is still much, much closer to pallidus than anything known in the Boletaceae at this time. Well, if that is the case, pallidus doesn’t have to be lonely anymore. Now it has a friend. :-)

Igor, Igor, Igor! What AMAZING work
By: Judi T. (AvidAmateur)
2017-01-06 06:32:48 IST (+0530)

on your part. You have managed to give some genuine clarity to 7 or 8 observations that have perplexed us all for about two years now. Way to go!!! I am indebted to you for your persistence and your expertise. This mystery has confounded me for so long; I can die a happy woman now:)

The latter part of your “Conclusion” reminded me of a comment Kuo made re: B. pallidus, i.e., that “this species is highly variable” and “possibly part of a species group”.

So next summer when these robust specimens pop up again in the same place, as I am certain they will, I’ll be able to look at them, not with chagrin, but with a sly smile; and you might even hear me say under my breath, “I’ve got you now.”

Thank you so much for following through on this ID. Your work is truly a credit to Mushroom Observer.

DNA sequencing results and discussion
By: I. G. Safonov (IGSafonov)
2017-01-06 02:12:33 IST (+0530)

Molecular Sequencing Results and Discussion:
>> A clean and contiguous 1441 bps nrLSU sequences has been obtained for this voucher. The sequence has 5 ambiguous characters: two R (corresponding to the purine bases A or G) and three Y (corresponding to the pyrimidine bases C or T). A GenBank search of the full-length sequence did not return anything meaningful. A sequence fragment (the first 976 characters) search yielded Boletus variipes AF457408 (869/875 = 99.3% similarity; no gaps; 4 of the mismatching bases correspond to the ambiguous characters; revised similarity = 99.8%) and Boletus pallidus AF457409 (864/875 = 98.7% similarity; no gaps; 4 of the mismatching bases correspond to the ambiguous characters; revised similarity = 99.2%) as the two top hits. Interestingly, AF457409, used in the well-known study of Nuhn et al. (2013), originated from Germany – this doesn’t make sense, as to my knowledge B. pallidus is a strictly North American taxon. All the other nrLSU sequences on the hit list have no more that 95% similarity to my sequence, and are thus irrelevant to this discussion.
Suspecting that B. variipes AF457408 is a misidentification and also being surprised at the fact that the above GB search did not return more sequences of these two common species, I ran two separate queries: specifically matching my sequence only with GB data for B. pallidus and for B. variipes.
Much to my satisfaction, the first targeted search returned two more highly similar hits for B. pallidus: KC812308 (593/597 = 99.3% similarity; no gaps; 3 of the mismatching bases correspond to the ambiguous characters; revised similarity = 99.8%) collected in New Hampshire and KC812310 (566/570 = 99.3% similarity; no gaps; 3 of the mismatching bases correspond to the ambiguous characters; revised similarity = 99.8%) collected in Massachusetts. Both vouchers were collected by J.L. Frank. Since the two sequences are much shorter than mine, it’s not surprising they didn’t show up in the global BLAST search.
The B. variipes targeted search returned three more sequences labeled as such: HQ161846, JQ327014 (A.H. Smith’s voucher for var. fagicola) and EU232003. However, these three sequences were highly dissimilar from mine (90+ bases off, over 2 dozen gaps; <90% similarity). As an additional test, I also aligned the full-length LSU sequence of my own B. variipes voucher, obs 217124, with that of this observation – the overlay was 114 characters off, and had 25 gaps. These results prove that both AF457408 and MO244148 are NOT B. variipes. Indeed, the morphology of MO244148 never supported the B. variipes proposal to begin with.

>> A 619 bps nrITS sequence was also obtained for this observation. There were some difficulties experienced in obtaining this sequence: 1) more than one haplotype present and 2) non-specificity problem that does not allow for a clean and contiguous end-to-end read. The final sequence is actually a stitch of two fragments from forward and reverse reads. It’s also worth mentioning that there are 3 ambiguous characters in this sequence: K = G or T, S = C or G, strong pairing and Y = C or T. This might be the “stitch" region where the sequence was non-specific. K and S characters were next to each other and Y was only 4 bases away from them.
A GenBank BLAST search of the full-length nrITS sequence returned 5 top-scoring hits, all representing vouchers identified as Boletus pallidus: JN020986, GQ166909, KC812309, KC812307, and FJ480440 (cf. pallidus). The presence of the ambiguous characters reduces the similarity to the 99.2-99.5% range, but the identity index is still very high.

Even before sequencing, I opined that this bolete (collected by Judy in the same location/spot in the past and posted as obs 208129, obs 208130, obs 208567, obs 209237, obs 244148, obs 253128, and possibly obs 245089) looks similar to Boletus pallidus. Now, the nrITS and nrLSU sequences obtained for the present collection support this notion – they are highly similar to many GenBank sequences associated with voucher collections identified as Boletus pallidus. Thus, at this time, barring any further evidence to the contrary, this taxon is best identified as Boletus pallidus. However, there remains a “wrinkle”, eroding this otherwise confident identification. The main morphological differences between Judy’s bolete and the classic Boletus pallidus are the darker cap colors and the presence of the coarse, widely-spaced reticulation on the stipe. The latter feature could be a random developmental anomaly (perhaps caused by the weather conditions), but since it is consistently present in several collections made at different times, it is instead likely to be an inherent phenotypic trait of this species. This evidence points to the intriguing possibility that Judy’s bolete is a close relative of B. pallidus. Sequencing of additional loci may be necessary to support, or refute, this hypothesis.
Boletus pallidus represents a monotypic genus in the studies of Wu et al. (2014, 2016). Currently, the Pallid Bolete is a satellite lineage in the Imleria-Tylopilus association, one of the clade clusters nesting within the subfamily Boletoideae.

That’s GREAT news, Igor. I am so excited at the prospect
By: Judi T. (AvidAmateur)
2017-01-05 15:05:28 IST (+0530)

of pinning this one down. There are at least two other obs. of specimens from this site collected over the past two years … with that distinctive coarse reticulation and “peelng” stipe. Hopefully, all your work on this will help us all learn something new! Thanks so much.

ITS & LSU sequences are in
By: I. G. Safonov (IGSafonov)
2017-01-04 00:16:30 IST (+0530)

They and the accompanying discussion will be posted soon. It’s not too late to place your bets. :-)

Scott, thank you for your ID suggestions.
By: Judi T. (AvidAmateur)
2016-07-23 05:17:50 IST (+0530)

This mushroom has eluded identification for over a year; see the Comments in Ob. #209237 when I first posted it. It returns to the same site — within a foot or two — every summer. I mailed the dried specimen to I.G. today with the hope that he will be able to pin down the species definitively once and for all. He has been a bulldog about this one … very helpful. I personally find identification of Boletes to be extremely challenging. Your comments, suggestions, and votes are very much appreciated. I am trying to learn as much as I can about the enormous variety. Stay tuned=)

Judy —
By: I. G. Safonov (IGSafonov)
2016-07-23 02:28:12 IST (+0530)

Thank you very much!

Igor, this specimen is on its way
By: Judi T. (AvidAmateur)
2016-07-23 02:23:33 IST (+0530)

to you via priority mail. ETA Monday or Tuesday. Thanks again!

Great! You may be able to solve this mystery
By: Judi T. (AvidAmateur)
2016-07-14 00:56:03 IST (+0530)

once and for all=)

Yes, Judy,
By: I. G. Safonov (IGSafonov)
2016-07-14 00:53:47 IST (+0530)

I would be interested in a sample of your collection. Thank you. I will send you my address.

I.G., this specimen is in the dehydrator now.
By: Judi T. (AvidAmateur)
2016-07-14 00:43:09 IST (+0530)

Would you be interested in seeing it when it’s dried?

By: I. G. Safonov (IGSafonov)
2016-07-14 00:29:16 IST (+0530)

I think I could have asked you to save a specimen. DNA sequencing should be helpful.

P.S. You bave a mighty good memory!
By: Judi T. (AvidAmateur)
2016-07-13 23:38:39 IST (+0530)
Thanks for changing the ID, I.G.. That’s actually
By: Judi T. (AvidAmateur)
2016-07-13 23:38:05 IST (+0530)

what I meant to post. I do think this is the same species I found last summer under the same tree. That yard always has a host of Boletes, Russulas, and whatever this is under several old Oaks there. It’s like a mushroom farm! I was hoping that these additional pictures might help pin it down at least to genus. It drives me nuts that I haven’t been able to identify this one … and it’s so distinctive!

By: I. G. Safonov (IGSafonov)
2016-07-13 23:25:43 IST (+0530)

You found this before — see obs 209237 and comments therein.