A Bolete by Any Other Name... (by )

Mushroom of the Month: September, 2014

As many of you know the mushroom world has been going through a lot of changes in recent years with the onset of genetic sequencing. One of the main impacts of this has been the renaming or reclassification of not only singular mushrooms, but in some instances whole genera (heck, Suillus got its own family!). It sometimes seems that just about every mushroom we see in our local woods now has a new name or spot in the myco tree of life. And one of our most prized groups of local mushrooms, the boletes, is no exception. With the recent publishing of scientific papers some of their names have changed as well. So let’s dive in at the first official wave of name changes to impact our beloved Boletus.

*** A few important notes before we begin... One, I am only going to cover the more common stuff that you would encounter in the woods and would also be found under the genus Boletus in Mushrooms Demystified. Two, these mushrooms have for better or worse worked themselves into different discrete groups, which in turn prompted the creation of new genera.

The King Group  King Bolete photographed by Ken Stravropoulos courtesy of mushroomobserver.org

The heavy hitters of Boletus and the ones most are scouring the woods for once the first big fall rains arrive. These mushrooms have remained in the genus Boletus but with some species name changes. Here is what we have:

  • Boletus barrowsii – The “White King” bolete remains with no changes.
  • Boletus edulis var. grandedulis – The “King” bolete got “var. grandedulis” appended to its name. We may also have the true European king bolete here growing with imported pine trees, but that will remain speculation until the genetic work is done.
  • Boletus regineus – The “Queen” bolete, which used to be Boletus aereus, a misapplied European name. Thankfully the name change did not affect its edibility.

The Butter Group   Butyriboletus persolidus photographed by Ron Pastorino from mushroomobserver.org

Here is, in my opinion, the biggest change of them all. The “Butter” boletes have now been moved out of Boletus and into their own genus Butyriboletus. On top of that it looks like we have three local species instead of the traditional two. Here they are:

  • Butyriboletus persolidus – Our traditional “Butter” bolete, that beautiful, intense blue staining, rock hard edible bolete found with hardwoods. It used to go by Boletus appendictulatus.
  • Butyriboletus querciregius – The “Pink-capped Butter” bolete, aka the elusive cousin of the more common butter bolete. I have still never found this thing...
  • Butyriboletus autumniregius – The new one on the scene and what can at the moment be called the “other” pink-capped butter bolete. This one differs from the other both genetically and by preferred habitat. It grows with coastal conifers instead of with hardwoods. This is probably the one that grows with the pine (and matsutake) around the fire roads of upper UCSC campus.

The Cracked-Cap Boletes   Xerocomellus dryophilus photographed by Martin Livezey from mushroomobserver.org

These are usually way more common than any of the boletes we have covered thus far. Sometimes called the “Woodland” boletes, they flourish fall through spring in both our live oak and tan oak habitats (they like hardwoods). Identifying down to species can be tough, and we may have undescribed species or members going by European names. Basically, dry caps that crack, often staining blue, often reddish stipes, often parasitized by Hypomyces and even more often not worth eating...

So what matters here? For a long time they were in Boletus, then moved to Xerocomus, and now they are in Xerocomellus. Looks like they will stay in Xerocomellus with our one “true” Xercomus, Boletus subtomentosus, moving into its proper nomenclature home. Still with me? Current species:

  • Xerocomellus chrysenteron – The “Cracked Cap” bolete. Used to be B. chrysenteron
  • Xerocomellus dryophilus – Probably one you are not familiar with. Really pretty red-capped mushroom that is sporadic in the county, but often common where it does occur. Formally B. dryophilus.
  • Xerocomellus truncatus – Macroscopically very similar to X. chrysenteron and often difficult to tell apart. Used to be B. truncatus.
  • Xerocomellus zelleri – “Zeller's” bolete and supposedly the best edible of the bunch... put enough butter, salt and garlic on a piece of cardboard and it too can be the best edible in Office Max. Fifteen glasses of wine prior probably does not hurt either... Regardless, a really striking mushroom when fresh. Used to be B. zelleri.

Aurobolteus (Oh yeah! Those things!)

This change has been around for a while and is pretty easy. The boletes with the neon yellow pores are now in Auroboletus. We currently only have two which grow with hardwoods (both are edible). Some years they are scarce, some years abundant. Recently we had an abundant year and decided to cook them up for some UCSC students. They actually really liked them! Go figure...

  • Aureoboletus citriniporus – the dry capped one
  • Aureoboletus flaviporus – the slimy capped one

In Limbo...I guess what could be called the “poisonous” bolete group, these two are currently in limbo as to if they will remain in Boletus or go somewhere else. 

Boletus Eastwoodiae photographed by Ron Lawrence from mushroomobserver.org

  • Boletus amygdalinus – no common name that I know of. Orangish pores and intensely stains blue. Grows with hardwoods. Long thought to be poisonous, recent discussions and some unverified taste tests claim it is actually edible. That is NOT an invitation for you to find out for sure. But if you do let me know.
  • Boletus eastwoodiae – “Satan’s” bolete. Boletus satanas was a misapplied name. Huge and gorgeous. Some years scarce, some years fruiting in enormous quantities. Easy one to learn. This species is without question seriously poisonous! 

So there you have it. The current status on our local boletes, all of which could be wrong by this time next year See you in the woods...