I do study boletes and maybe this comment will
help. When trying to put a bolete into a genus it's useful to
remember that Boletus is a "trash-can genus". All that means is
after you tried to fit your bolete into every other genera and it
didn't fit anywhere else it MUST be a bolete. Tylopilus is the
most "Boletus-like" genera in terms of stature. It looks like the
edulis type group within Boletus as opposed to the Xerocomus group.
By that I mean it's big, chunky. thick stemmed, small rounded pores,
etc. The best feature for Tylopilus is the pore surface stains
brown, reddish, flesh-colored or pink. Most of the Tylopilus look
like the "edulis" group of Boletus but they have white pore mouths
(never yellow or red) that turn one of the colors I mentioned above.-
It's unfortunate the Tylopilus felleus is the type species for
the genus Tylopilus because none of the other North American
Tylopilus are reticulated that conspicuously. Ernst Both is fond
of pointing out that Tylopilus felleus is probably a European bolete
that came to North America by way of the nursery trade when spruce
trees (Norway Spruce?) were shipped here.

Bill Y