Observation 295394: Boletus L. sect. Boletus

Reddish cap, olivaceous pore surface, non-staining, white finely-reticulate and slightly bulbous stipe. Flavor and odor are mild. Growing under oaks.

Species Lists



Proposed Names

59% (2)
Recognized by sight
28% (1)
Based on chemical features: Unique ITS that doesn’t fall into any Boletaceae genus

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= Observer’s choice
= Current consensus


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Thanks for the update Igor.
By: Ron Pastorino (Ronpast)
2019-06-09 22:24:50 +03 (+0300)

Interesting that mine was found in June and Logan’s in Oct.

Age of porcini s.l. lineages
By: I. G. Safonov (IGSafonov)
2019-06-07 19:24:11 +03 (+0300)

Logan, here is the answer to your question from Dr. Dentinger:
“This is difficult to answer. First, the topology and branch lengths of the ITS tree is probably not reliable at the deeper nodes. Also, statements of the relative ages need to consider the stem vs crown ages. Thus, the stem age of the edulis clade is roughly the same as the stem clade of “alloboletus”, whereas the crown age is slightly older than the crown of “alloboletus”. But, they are so similar I would venture a guess that they have diversified at roughly the same time and rate.

However, MO295394/MO279831 is older than the stem of the edulis clade and the stem of “alloboletus” (it is approximately the same age as the ancestor of edulis + alloboletus). It is certainly an old lineage and provides tremendous insight into the origin of the group, particularly because it adds the Americas into the ancient grade of early diverging porcini that were otherwise known only from Asia and Australia.

I wouldn’t put much stock in the absolute dates — there is no fossil evidence to support them and without corroborating evidence, it’s a guess at best."

Thank you…
By: I. G. Safonov (IGSafonov)
2019-06-07 06:12:51 +03 (+0300)

so much, Logan. Then every minute of the very long time I put into composing my answer to your question was worth my while. :-)
Here is another thought. Recall how dissimilar the ITS sequence of MO295394 is from everything else in the BLASTn search? Not even a vague indication that it’s in the Boletus s.s. clade, just non-specific random hits from other genera at low % similarity and low query cover. I think this ‘artifact’ could be indicative of how ancient this critter is and how distant it is genetically from the more recently-evolved porcini taxa that dominate the scene. Yet, the gestalt morphology, including the hallmark manifested in all procini taxa (the hyphal layer over the pores), speak the truth. On second thought, maybe Dr. Dentinger has a better software than what’s in GenBank that puts this species more readily into the porcini clade.

A fantastic answer!
By: Logan Wiedenfeld (LoganW)
2019-06-07 05:20:04 +03 (+0300)

Thank you, Igor. This is really fascinating information. I appreciate your rigor.

By: I. G. Safonov (IGSafonov)
2019-06-07 04:27:38 +03 (+0300)

I’ve posed Dr. Dentinger with this question of yours, but haven’t received a reply yet. Here are my thoughts on the subject and some literature inferences:
I don’t know if the gross branching pattern in a phylo tree represents the true chonology/timeline of the evolution of lineages within a monophyletic clade.
There are molecular clock analyses and the associated chronograms for that, which are derived from phylo trees though. It is conceivable, however, that gross phylo tree topologies could give insights into the rough chronology of evolution. Basically, if the relationship patterns seen in trees are any indication of possible evolutionary paths, then ancestral nodes and the associated branches closest to the root of the tree (i.e., the last common ancestor of the whole clade) should in theory represent the oldest lineages and their extant (relic) taxa. Note that branch lengths have nothing to do with the actual age of taxa or lineages; instead, they represents the evolutionary time between two nodes measured in substitutions per sequence site.
As far as porcini s. lat. (=Boletus s. str.) are concerned, Feng et al. (2012) have this figure titled “Chronogram and estimated divergence times of porcini s.l. generated from molecular clock analysis using the RPB1-nrLSU data”. They put the initial radiation of the porcini at ~77 million years ago (Mya) at the end of the Cretaceous Period/Mesosoic era, just 11 million year before the last mass extinction of earth’s flora and fauna (3/4 of species perished) famously marked by the end of the reign of dinosaurs. Specifically, the “Alloboletus” lineage is the oldest one (diverged ~77 Mya), followed by “Obtextiporus”/B. albobrunneus (diverged 70 Mya), “Inferiboletus”/B. austroedulis (diverged 59.5 Mya), and “Orientiboletus”/B. griseiceps (diverged 55 Mya). Porcini s. str. (aka, the “Edulis-clade”), the most diverse lineage species-wise in Boletus s.str., is much younger (diverged ~38 Mya). Also, it can be inferred from this chronogram that some of the species in “Alloboletus” diverged at a much later time than the relic taxa from the other three lineages.
Looking at Dr. Dentinger’s ITS tree, the splitting pattern suggests the following evolutionary progression: “Inferiboletus” (ancient)—>"Orientiboletus"—>MO295394—>"Alloboletus"—>"Obtextiporus" (old)———→ porcini s.str. (youngest).
So, how old is the lineage represented by MO295394 relative to the four ancient porcini s. lat. lineages? Probably comparable in age (split off 55-77 Mya) or possibly somewhat younger, but likely much older than the “Edulis-clade”/porcini s. str. Feng et al. suggest that the origin of porcini s. lat. is tropical because the few extant representatives from the four older lineages are found only in/near the Paleotropics, whereas later diversification within “Alloboletus” and the “Edulis-clade” is represented by species found in the broad temperate zone. So far MO295394 is known only from the southern end of the Nearctic realm (subtropics). Could its current geographic distribution be a reflection of the age of the lineage it represents?

Igor – A question:
By: Logan Wiedenfeld (LoganW)
2019-06-06 07:11:10 +03 (+0300)

In terms of evolution, the position of this taxon on Dr. Dentinger’s tree suggests what exactly? that this is a more primitive phylogenitic iteration within Boletus sect. Boletus? I need to get better at parsing these trees. I think I understand the significance of contiguity better than the significance of being lower or higher on the “tree.”

(On a side note, I love how pumped Dr. Dentinger appears to be about Ron’s collection. From one of his posts about the porcini tree: “Holy smokes look at MO279831!!!! Major evolutionary novelty there. What a discovery! This taxon has MASSIVE implications for biogeography…” I’m happy that we were able to extend the range distibution a couple hundred miles!)

By: I. G. Safonov (IGSafonov)
2019-06-05 21:05:10 +03 (+0300)

This species (279831, 295394 and likely 334991 + Co.) is not part of Alloboletus. In Dr. Dentinger’s ITS tree it shares a terminal nodal point with one of two spp. nov. from Sarawak, Malaysia (76% bootstrap support). This sub-clade is the third up from the basal position occupied by B. austroedulis and directly below Alloboletus.

Also very cool!
By: Logan Wiedenfeld (LoganW)
2019-06-05 20:39:37 +03 (+0300)

I wonder where within Boletus s. s. this critter is phylogenetically situated. Ron’s collection looks more like separans, so Alloboletus, maybe?

This critter is porcini, indeed
By: I. G. Safonov (IGSafonov)
2019-06-05 18:07:11 +03 (+0300)

I just heard from Dr. Dentinger. He writes: “MO295394 is identical to MO279831. I now have a full genome sequence for MO279831”.
So my early suspicions about the conspecificity of the two (see my first comment below) has been confirmed. For some reason I didn’t make a connection with Logan’s MO334991 and others listed therein.
It’s interesting that ITS is not helpful at all in supporting the identification of this species as Boletus s.s. from gross morphology.

Great, thanks!
By: I. G. Safonov (IGSafonov)
2019-06-05 06:26:12 +03 (+0300)
I have some of 334991
By: Logan Wiedenfeld (LoganW)
2019-06-05 06:20:07 +03 (+0300)

I can get it to you in my next shipment :)

By: I. G. Safonov (IGSafonov)
2019-06-05 05:58:51 +03 (+0300)

Indeed, there is a good chance this collection is conspecific with obs 334991. Thanks for pointing this out to me. If you have that one and/or any of the related obsies listed therein, send it/them in sometime before October so that I can include samples for the next round of sequencing. Thanks!

By: Logan Wiedenfeld (LoganW)
2019-06-05 05:38:24 +03 (+0300)

I would have thought this was a dead ringer for “porcini sensu lato.” Consider obs 334991 (and the appended obsies). The taxon there represented, whatever it is, sports stuffed pores in buttons, has the reticulate, often bulbous stipe, does not stain, and so on. Maybe these are different than this (than 295394, in other words)? Or maybe they’re all the same and yet all removed from Boletus sect. Boletus?

It’s cool, in any case, that this organism is so singular. I’ve stalked this particular suburban lawn (the lawn of a stranger, unfortunately) in the hopes that I’d see a fruiting body from this particular organism again but have come up short a couple years running. Maybe I’ll get lucky this summer. Fingers crossed.

Thanks for the exciting news, Igor. Great work! (Please extend my thanks to Dr. Kudzma, as well.)

DNA results & discussion
By: I. G. Safonov (IGSafonov)
2019-06-05 05:11:34 +03 (+0300)

ITS was requested for this voucher because it looks like a porcini. The material gave a weak DNA extraction, so repeated nested PRC was required. Fortunately, Dr. Kudzma succeeded in getting “great data”, which is uploaded to this post.
The full-length nrITS sequence is 603 bps long (ITS1 = 188 bps, 5.8 = 161 bps, ITS2 = 254 bps).
A BLASTn of this entire sequence returned a strange hit list. First, the highest similarity is 90%, query covers for 94 out of 100 hits are almost invariably only 70-74% and E-values are greater than zero (e.g., 3e-133). Second, the list consist of random Boletaceae hits – i.e., there are no discernible patterns that would indicate this species falls into any particular known genus in this family!
A separate BLASTn of the ITS1 region returned a hit list that was only 9 accessions long (!) instead of the expected 100 (default setting in GB)! All hits had similarity in mid-80%, query covers of only 45% and very high E values.
Lastly, a separate BLASTn of the ITS gave a profile similar to the two previous runs — similarities below 90%, low query covers of 66-68% and high E values.
Whatever this critter is, it must be quite unique. I don’t think it’s a porcini based on the DNA results, though the morphology points that way. Still, just in case, I will ask Linas to sequence the ITS of obs 279831, which this collection somewhat resembles. I only have TEF-1 for that collection.
Logan, if you find this mushroom again, please make sure to dry it very thoroughly and store it a cool, dry place. I would like to follow up with another locus or two. Also, think about writing a detailed morhological description of it.

By: I. G. Safonov (IGSafonov)
2017-10-23 22:32:04 +03 (+0300)

Thanks for the head up on the package. I will let you know when I get it.
I am glad you are taking proper care of your awesome bolete collections. You may want to think about writing preliminary descriptions and mining for some appropriate provisional names. We’ve got to call these critters something, right? :-)

I saw that
By: Logan Wiedenfeld (LoganW)
2017-10-23 19:44:22 +03 (+0300)

one, Igor, and thought the same thing. They look similar.

I have this one on the dryer now. To my knowledge, it’s the first of its kind that I’ve encountered here.

(On a semi-related note, I’ve got a package headed your way. USPS says it should be there tomorrow.)

Interesting collection, Logan
By: I. G. Safonov (IGSafonov)
2017-10-23 19:39:08 +03 (+0300)

I happen to agree with your proposal… in the absence of any evidence to the contrary. The Gulf area is producing unusual porcini types, if that’s where this critter belongs. I wonder if this is similar to Ron Pastorino’s obs 279831. That collection has recently been submitted for sequencing.

Created: 2017-10-23 17:35:30 03 (0300)
Last modified: 2019-07-06 00:55:28 03 (0300)
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