Observation 280000: Boletus separans group

Found in pairs growing near each other in mixed woods.
Caps dry, up to 10.1 cm across.
The caps were wrinkled/pitted to varying degrees.
Stipes with varying degrees of light reticulation and some ribbing.
Flesh white and unchanging.
Taste mild.
Pores white and seemed to be initially turning light yellow.
Spore print was light but appeared reddish brown.
Spores in 2% KOH were orangy brown under the microscope.
Spores ~ 12.9-15.6 X 5.3-6.9 microns, subfusoid and smooth.
Interesting combination of colors and characteristics…think I need help again.

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Spores in 2% KOH @ 1000X

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3% (2)
Recognized by sight
31% (2)
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38% (3)
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75% (2)
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Add Comment
Specimen accessioned to the University of Utah fungarium
By: Dan Molter (shroomydan)
2018-10-10 14:43:34 -05 (-0500)

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


This collection…
By: I. G. Safonov (IGSafonov)
2018-04-11 11:15:40 -05 (-0500)

…(the entire portion RLP sent me) was transferred to Dr. B.T.M. Dentinger at UMNH in March 2018.

I have to agree…
By: Ron Pastorino (Ronpast)
2017-06-26 16:22:08 -05 (-0500)

at least my single fb from from obs 207733 is very likely the same as these.
The spores look almost identical in color, shape and size. My notes from that one say that the print was weak and “brownish”.
Hard to explain the difference in width of the spores, which is significant. Will try to check some older references to see how consistent the numbers are.

The map of B. separans observations…
By: I. G. Safonov (IGSafonov)
2017-06-26 13:05:58 -05 (-0500)

… shows two collections from TX, both by Ron (obs 3487 and obs 207733), one from LA (obs 250065) and two from Mexico (obs 210387 and obs 241774). According to NAB separans is distributed widely in the USA (west to MI and TX). Given it’s a highly variable in appearance taxon (the colors and amount/intensity of reticulation), it’s possible 280000 could be separans. The spore width doesn’t match the literature values, but there could be explanations for that.

Thanks for the info, Ron
By: I. G. Safonov (IGSafonov)
2017-06-26 09:50:52 -05 (-0500)

Maybe the PV was there when the fbs were younger. Judging from the spore width and the observed color of the spore print, this is not B. separans, but I would still place this collection in Alloboletus sensu Dentinger et al. (2010) rather than porcini s.s., provided it’s indeed a member of sect. Boletus. Hopefully we will get a better idea once this gets sequenced.

Igor, I didn’t notice any stuffed pores
By: Ron Pastorino (Ronpast)
2017-06-26 09:15:55 -05 (-0500)

on them.
Also I didn’t carry any ammonia solution on this trip.
I’m not 100% 0n the color of the spore print as it was sparse, and I was going through a lot of collections.
The rather dark color of the spores in KOH under the microscope seems to indicate the color had to be fairly intense, with a reddish element to it.

By: I. G. Safonov (IGSafonov)
2017-06-26 08:56:24 -05 (-0500)

The yellowing pore surface would suggest a member of Xanthoconium (pores originally white), but the overall morphology is somewhat evocative of B. separans and the spore print is not yellowish-brown as it should be for Xanthoconium. It’s interesting that separans was once in Xanthoconium because of its spore print color.
Ron, was there any reaction to ammonia on cap and/or stipe? Did the younger fruiting body have a PV (aka “stuffed pores”)?