Observation 286122: Xerocomoideae Singer

When: 2017-08-12

Collection location: Bear Creek Park, Dundalk, Maryland, USA [Click for map]

Who: Ryan Patrick (donjonson420)

No specimen available


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One of my favorite spots for hardwood associating boletes…
By: Dave W (Dave W)
2017-08-15 02:14:44 AEST (+1000)

has yet to produce any significant flushes this year. There’s generally some hortonii available. I’ll check this week.

Well done!
By: Roy Halling (royh)
2017-08-15 01:32:29 AEST (+1000)

I’d forgotten about the poster that Beatriz did in collaboration with M. Kuo. That’s an enlightening piece of work. Hortonii grows in a spot reliably, but infrequently, here at NYBG – should grab some more.

Hello, Roy
By: I. G. Safonov (IGSafonov)
2017-08-15 01:18:59 AEST (+1000)

Thanks for chiming in.
I’ve always wondered about hortonii being placed into Xerocomus, but never investigated the taxonomic origin of this placement. Morphologically subglabripes and hortonii are indeed very similar, so one can make a reasonable argument about Hemileccinum hortonii from the morphology alone. Based on M. Kuo’s research on leccinoid fungi, one can make a convincing argument in favor of H. hortonii: http://www.mushroomexpert.com/leccinumposter.pdf. TEF-1 data place impolitus, hortonii, and sugblabripes into a strongly supported monophyletic clade, and we know that the first and third species already reside in Hemileccinum.

Good question,
By: Roy Halling (royh)
2017-08-15 01:08:31 AEST (+1000)

re: hortonii compared to subglabripes. As near as I can tell, only one exemplar of hortonii has been sequenced (GenBank AF139713) AND only for the 28S (LSU) gene. In 2000, Binder & Besl (sorting out Leccinum) made the comb nov. for hortonii to Xerocomus based on that data. They also used some chemotaxonomic data for the sorting as well. Maybe some additional genes need sequencing?

As Igor noted, Hemileccinum is inferred to belong in Xerocomoideae as well, but is some distance removed from Xerocomus according to Wu et al (2016) based on at least 3 genes.

I wonder why subglabripes…
By: Dave W (Dave W)
2017-08-14 13:52:37 AEST (+1000)

isn’t placed into Xerocomus? The very similar hortonii is (currently) a Xerocomus (according to IF).

By: I. G. Safonov (IGSafonov)
2017-08-14 12:24:19 AEST (+1000)

Ideas and brainstorming is all we can do right now… till Ryan find this again and it gets sequenced. By the way, Hemileccinum is also in Xerocomoideae. :-)

One reason why I didn’t just propose subglabripes…
By: Dave W (Dave W)
2017-08-14 12:18:30 AEST (+1000)

was the faintly subreticulate/ribbed stipe apex. This does support the Xerocomoideae proposal. Also, the cap surfaces appear to be slightly textured… subtomentose. But, seeing this as a fairly ambiguous collection, I think it’s good to get ideas onto the table.

By: I. G. Safonov (IGSafonov)
2017-08-14 12:00:10 AEST (+1000)

Not an unreasonable proposal, but how do those reticulated stipes fit into the subglabripes species concept?

How about…
By: Dave W (Dave W)
2017-08-14 11:21:24 AEST (+1000)

the “southern form” of Hemiboletus subglabripes? The whitish stipes seem to not fit, but I have seen the northern version with pale stipe lacking ornamentation.

By: Ryan Patrick (donjonson420)
2017-08-13 12:57:58 AEST (+1000)

No sample unfortunately I’ve been traveling light lately. Ill be on the lookout when returning to this site.

For some reason I am getting…
By: I. G. Safonov (IGSafonov)
2017-08-13 12:48:48 AEST (+1000)

Xerocomus sp. vibes from this one, but none of the usual suspects, and the gestalt doesn’t ring any obvious bells. The yellow stipes with some brown staining look vaguely familiar, but I am drawing a blank at this time.
Even if this is an Aureoboletus, it’s still in the subfamily Xerocomoideae. I think we are both fishing in the right pond. Can you sequence this one, Ryan?

No additional photos
By: Ryan Patrick (donjonson420)
2017-08-13 12:24:17 AEST (+1000)

It seems your right, thought I had this pegged in the field. But after cross referencing photos and descriptions Aureoboletus innixus is not it. Running through the key quickly nothing seems to match. Any ideas?

By: I. G. Safonov (IGSafonov)
2017-08-13 12:17:22 AEST (+1000)

For some reason the impression I get from your pix doesn’t really evoke the gestalt of innixus. Isn’t there a wide-mesh subtle reticulation visible in the upper half of the stipe. What do you think? Do you have more pix of this collection?