Tapinella atrotomentosa which is also known as the velvet roll-rim is a robust saprobic fungus I had the privilege of meeting last weekend. I was at my in-laws annual family gathering located on land they own in Warsaw NY. It’s always a pleasure to catch up, laugh, eat, and sip on some craft brew with them, but if you know me by now, you can understand how loud the forest behind the central cabin area was calling my name.
Meandering through the woods, only hearing but a faint jabber of a large Scottish and Irish family amped up on some liquid courage, I began to find one cool species after another. It had just rained heavily on that Thursday, like, torrential downpour status, so the forest floor was teaming with life. Even though the brownish cap of T. atrotomentosa blends in with the fallen pine needles and leaves surrounding its base, this mushroom sticks out like a sore thumb.
To the untrained eye, this mushroom may seem a bit mundane, but for the fungal hobbyist, this species is anything but. It has a walnut colored cap covered by fine smooth hairs, hence its common name. Its gills are a light, creamy shade of yellow that run down the stipe a bit, a term in mycology coined decurrent gills. Its stipe has a dark hue of brown similar to the cap due to those same velvety hairs being attached. In Latin atrotomentosus aptly means "black-haired.”
This species grows on dead conifers, so it makes sense that I found several groupings of hungry T. atrotomentosa covering the base of dead white pines. When I pulled one of these mushrooms out of the ground, I was shocked at how sturdy the species was. Most gilled mushrooms I encounter are quite fragile, unlike this specimen that was extremely dense. Another thing I found interesting was that it was largely untouched by feeding insects and slugs. Almost every other species I encountered in the woods at Warsaw were completely dismantled by some type of herbivore. After a bit of research in my tent, I began to unfold the patterns I saw.
As it turns out, this mushroom is from the order Boletales, which explain its structural integrity. Boletes are usually denser, more sturdier mushrooms than gilled mushrooms. Once again, the ancestors of this Bolete had a genetic mutation that transcribed the codons for its more ancient gilled morphology. I talk about this in a previous post with another gilled bolete. Gills are fantastic appendages for spore release, so a species that switches form a pore to a gilled morphology isn’t negatively affected, and the new set of genes is conserved in the gene pool.
This fascinating gilled bolete is hiding something else too, volatile compounds that deter herbivory. Like I said earlier, most fruiting bodies in this mixed habitat were barely standing up, because of the intense feeding of slugs and snails. The reason why this species was largely untouched is that upon any damage, the fungus converts leucomentins, chemicals within its tissue, into several other compounds including the feeding deterrent osmundalactone. Many fungi, including truffle-forming ones and even some boletes depend on animals to eat their fruiting bodies to disperse their spores. Clearly though, this species solely relies on wind dispersal to send its offspring to the stumps of dead conifers.
Once placed in the genus Paxillus, T. atrotomentosa and its closely related cousin T. panuoides were moved to the genus Tapinella. Mycologists first began to question this mushroom as a Paxillus species because they realized that most if not all Paxillus species form mycorrhizal mutualisms with trees. Their different ecology along with some genetic analyses confirmed its placement to the genus Tapinella.
Even when you’re celebrating with friends and family, if there are woods nearby, don’t be afraid to take a gander. If anything, you can take a specimen back, and it will become a bit of a conversation starter. At first, I thought I brought back a true gilled mushroom from the order Agaricales. Surprisingly, I found another bolete that had reverted back to its more ancestral gilled condition. I also soon uncovered the reason why this fungus remained intact in the wake of a million hungry slugs. I am constantly being taught by nature, and I hope I can continue translating that information to you. It takes a lot of discipline to be a student of the wilderness, you just have to remember to listen, for the forest floor is calling your name.