Observation 282673: Boletus variipes group

Notes:
A single young and robust fruiting body growing in moss under old oaks. The flesh was practically undamaged by insects.
This was my current/benchmark morphological concept of atkinsonii – an all-brown mushroom with brown reticulation. The cap margin bruised purplish-red on both cap and stipe upon holding the mushroom in hand for a while. Ammonia on cap was purple/magenta where the vapors hit the cuticle; the drop itself stained the cap orange-red (see pix). This profile is consistent with a picture of this reaction posted at http://www.mushroomexpert.com/....

Half of this collection was transferred to Dr. B.T.M. Dentinger at UMNH in March 2018.

DNA Sequencing Results (last updated 14-Nov-18):
> A clean and contiguous 1007 nrDNA sequence was obtained from this collection and uploaded to this observation. It consists of the last 639 characters of nrITS, followed by the first 368 characters of the nrLSU region. There are no ambiguous characters present, this is a single haplotype.
> A BLASTn search of the nrITS sequence only yielded the following relevant results (sorted by % identity):
EU231958: Boletus variipes BD245 collected by B.T.M. Dentinger under beech in Duke Forest in North Carolina = 625/625 = 100% match
EU231957: Boletus aff. variipes var. fagicola REH8545 collected by R.E. Halling et al. under oak and pine in Belize in 2003 = 619/620 = 99.8% match
EU231956: Boletus aff. variipes var. fagicola REH8527 collected by R.E. Halling et al. under oak in Belize in 2003 = 619/621 = 99.7% match
JN020994: Boletus variipes BD369 collected by B.T.M. Dentinger under beech in Costa Rica = 622/627 = 99.2% match1
EU231955: Boletus aff. variipes var. fagicola REH7756 collected by R.E. Halling et al. under oak in Costa Rica in 1997 = 611/622 = 98.2% match2
> A further inspection of the nrITS BLASTn results led to the discovery of a second cluster of relevant accessions of vouchers identified as B. variipes by their collectors. Though only 93-94% similar to MO282627, this group importantly includes the nrITS sequence of A.H. Smith’s B. variipes var. fagicola holotype (sorted by % identity):
KY826165: Boletales sp. voucher RL010 collected by R. Lebeuf in SE Canada3
KY826012: Boletales sp. voucher B0962 collected by Y. Lamoureux in SE Canada
KY826107: Boletales sp. voucher B3041 collected by Y. Lamoureux in SE Canada4
KY825988: Boletales sp. voucher B0246 collected by Y. Lamoureux in SE Canada5
EU231961: Boletus variipes BD201 collected by B.T.M. Dentinger under oak in Chestnut Ridge Park, south of Buffalo, NY
EU231963: Boletus variipes BD190 collected by B.T.M. Dentinger under hemlock, oak and beech in Allegheny National Forest, PA
EU231962/NR_119673: Boletus variipes var. fagicola AHS75914/MICH 10063 holotype collected by A.H. Smith in beech-maple-aspen woods near Wolverine, MI, in 1968
Discussion of Results:
Analysis of the above sequencing data (see the recently uploaded GenBank-generated phylogram consisting of the assorted BLASTn hits) coupled with a thorough literature research suggest this NJ collection belongs in the “Variipes-clade” of the porcini s. str. lineage of Boletus s. str./Boletus sect. Boletus by virtue of being conspecific with EU231958.6,7
As per Dentinger et al. (2010) and Feng et al. (2012), the “Variipes-clade” currently consists of three entities (at the phylogenetic resolution of nrITS):
1) The [ostensibly] undescribed taxon (or perhaps species group) represented by a large number of vouchers from a wide geographical range (Connecticut, USA, south to Florida and into Belize & Costa Rica)
2) Boletus variipes Peck/Smith & Thiers (from northeastern USA)
3) Boletus hiratsukae (endemic to Japan)

References:
1 This collection is called Boletus cf. variipes var. fagicola BD369 in Mol. Phylogenet. Evol. 2010, 57, 1276-1292. A photograph of it can be visualized in the above publication on p. 1278.
2 Of the 11 mismatching positions, 5 are gaps and 5 are ambiguous characters of “N”-type, which can represent any of the 4 nucleotides. Since it’s possible that at least some of these are editing errors, the actual % identity could be higher. A photograph of this collection can be visualized at http://sweetgum.nybg.org/....
3 Renée Lebeuf’s pictures of this collection are uploaded to this observation.
4 Original identification by Yves Lamoureux as B. variipes Peck. A photo of this collection can be found at https://www.flickr.com/... (courtesy of Renée Lebeuf).
5 Original identification by Yves Lamoureux as B. atkinsonii Peck. A photo of this collection can be found at https://www.flickr.com/... (courtesy of Renée Lebeuf).
6 Dentinger et al.: “Molecular Phylogenetics of Porcini Mushrooms (Boletus section Boletus); Mol. Phylogenet. Evol. 2010, 57, pp.1276-1292.
7 Feng et al.: “DNA Sequence Analyses Reveal Abundant Diversity, Endemism and Evidence for Asian Origin of the Porcini Mushrooms”; PLoS One 2012, 7(5), e37567.

Species Lists

Images

Ammonia reaction on cap
Copyright © 2012 Renee Lebeuf
Renee Lebeuf’s collection B. variipes from Canada3
Copyright © 2012 Renee Lebeuf
Renee Lebeuf’s collection of B. variipes from Canada3
Copyright © 2017 Prof. Bryn T. M. Dentinger

Proposed Names

86% (1)
Used references: See the above discussion
Based on chemical features: nrITS sequence and BLASTn results

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= Observer’s choice
= Current consensus

Comments

Add Comment
Specimen accessioned to the University of Utah fungarium
By: Dan Molter (shroomydan)
2018-10-10 14:34:14 -05 (-0500)

This specimen has been accessioned to the UT fungarium with the following number:

UT-M0000508

Renée,
By: I. G. Safonov (IGSafonov)
2017-07-22 16:36:54 -05 (-0500)

I am a bit confused… If the finely cracked cap in young age is a trait of atkinsonii, as per your observation/comment, how can it at the same time be variipes?
I don’t think this is variipes on account of the purplish staining when handled and the magenta reaction on the cap with ammonia (I will post a picture of the reaction soon).
In the past, I have found other oak-loving, summer porcini types from this location: obs 104260, obs 104261, obs 104263, obs 139118 and obs 139124. I don’t think they are the same species, but one or more of them could be the same as 282673 (e.g., 104260 that has the same purple staining when handled — see the past photo in that obsie).
This mushroom was too young to drop spores (the pores were “stuffed”).

On the image you show of the purplish reaction you see that the cap is finely cracked
By: Renée Lebeuf (Renée Lebeuf)
2017-07-22 15:21:01 -05 (-0500)

I find that this is the main distinctive character of B. atkinsonii. It is observed even on young fruitbodies. For that reason, could your bolete be B. variipes? Genetics should tell. According to Smith & Thiers, the spores of B. atkinsonii should be on average 13 µm long, whereas they measure 15 µm in B. variipes. Or maybe there are cracks on your specimen?