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When: 2020-07-25

Collection location: Interlochen, Michigan, USA [Click for map]

Who: Eric (eozkan)

Specimen available

Collected this beautiful bolete mushroom emerging from leaf litter in a mixed woodland. Pore surface immediately turns blue when bruised.

Species Lists


Proposed Names

56% (1)
Recognized by sight: Either P. sclerotiorum or (more likely) its lesser known lookalike prepresented by the following sequenced collections: obs 286328 (NJ) and obs 331470 (MI)
84% (1)
Based on chemical features: The derived full-length ITS sequence (uploaded to this obsie) is a 99.4-100% match to numerous GenBank accessions of P. sclerotiorum, including that of the holotype,

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= Observer’s choice
= Current consensus


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DNA results & discussion
By: I. G. Safonov (IGSafonov)
2020-12-09 20:48:33 CST (-0600)

A clean and contiguous nrDNA sequence of 789 bps was obtained by Dr. Kudzma from this collection and uploaded to this observation. It consists of the last 22 characters of nrSSU, followed by the full-length ITS region of 700 bps and then by the first 67 based of nrLSU. It’s a joined contig, rather than a 2-read consensus sequence, because of a single point of heterogeneity seen in both reads in the middle of the ITS1 region near the octa-“CA” polymeric motif. However, there is a bit of common overlap between the forward and reverse reds that allows for the sequence to be confidently stitched together. The data are good and solid.
There is no question about the identity of this collection as its ITS sequence is a 99.7% match to that of the Floridian holotype collection of Pulchroboletus sclerotiorum, The two sequences differ only in the number of “CA” units in the aforementioned polymer.
The importance of this collection lies in its geographic location. I have long believed that P. sclerotiorum was restricted to the eastern seaboard (based on the MO observations, as well as the metadata listed in GenBank accessions). Indeed, known sequenced collections originate from the coastal areas of MA, CT, NJ, DE, VA, FL and TX (personal and GenBank records); however, one GenBank accession hails from TN, which obviously falls well outside of the above geographic range. This MI voucher happens to be the northernmost and westernmost sclerotiorum collection to date. Michigan can be considered a “maritime” habitat because it’s straddled by the Great Lakes.

By: I. G. Safonov (IGSafonov)
2020-07-26 19:52:03 CDT (-0500)

I made a mistake in my previous comment, so I had to edit it — I changed the name from miniato-olivaceus to miniato-pallescens.

You’re welcome, Eric [edited]
By: I. G. Safonov (IGSafonov)
2020-07-26 06:15:21 CDT (-0500)

Your two posts are the second and third examples of the ‘scelerotiorum group’ from MI we know of on MO. I wonder if Smith and Thiers had come across this mushroom and published it in their book, The Boletes of Michigan. The best candidate for it appeared to be Boletus miniato-pallescens, but it’s a much larger bolete. Though the macro- and microscopic characters are very similar, both Alan Bessette and I think miniato-pallescens is a different mushroom.
There are plenty of bicolor-like boletes out there, and by that I mean entities from various genera featuring the two-color scheme — red cap, yellow pores and yellow or yellow red or mostly red stipe. The closest lookalike of Baorangia bicolor is perhaps Lanmaoa pallidorosea, especially when comparing young/immature mushrooms, but once you find a real bicolor a couple of times, you will never confuse it with anything else. Also, B. bicolor generally doesn’t blue much at all, and has a very thin tube layer even at maturity and a smooth/continuous transition of the pore surface into the stipe. Here is a picture of bicolor and pallidorosea together from an observation of mine: (bicolor is on the left; both collections sequenced).

Thank you for the clarification Igor! Didn’t realize these occurred in Michigan…
By: Eric (eozkan)
2020-07-26 00:51:45 CDT (-0500)

…but will study some of the other observations to help me distinguish them. To my
inexperienced eyes, really looked like B. bicolor. These are the first I’ve found.