Tom Volk's Fungus of the Month for February 1999

This month's fungus is Armillaria nabsnona, honey mushroom number nine

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Armillaria nabsnona type specimenThis month's fungus of the month is one of the honey mushrooms, Armillaria nabsnona. Usually the specific epithet tells you something about a fungus-- what does "nabsnona" mean? I'll tell you more about that later.

Armillaria nabsnona Volk & Burdsall was described by us from specimens I collected on the Olympic Peninsula in 1994, just after the North American Mycological Association (NAMA) annual foray was held at Port Townsend, Washington. For the technical descriptions of Armillaria nabsnona see the actual paper online in which we formally described the species:

Armillaria nabsnona, a new species from western North America. Thomas J. Volk, Harold H. Burdsall, Jr. , and Mark T. Banik. Originally appeared in Mycologia 88:484-491. 1996

On this page I'll describe the adventure of collecting this particular species. But first you'll need to know a little background about the genus Armillaria. Many of the detail are on another of my pages, The state of taxonomy of the genus Armillaria, but I'll summarize that here.

Up until fairly recently there was considered to be only a single species of Armillaria, namely Armillaria mellea(Vahl:Fr.) Kummer. Until the late 1970s Armillaria mellea (Vahl:Fr.) Kummer was considered by most researchers to be a pleiomorphic species with a wide host range and distribution. It was considered by different researchers to be either a virulent pathogen (in the west) or a opportunistic pathogen (and then not very virulent) in the eastern United States. Its host range was phenomenal, one of the broadest known for fungi, and its morphology was extremely variable.

Since fruiting body morphology proved difficult, other avenues of research were followed. The most productive was placing single spores of different fungi in agar medium and seeing whether they would mate. If they did mate, two specimens were considered to be the same biological species. You can read about the details of how this was accomplished in The state of taxonomy of the genus Armillaria, but the end result was that there are TEN North American Biological Species (NABS) and five European Biological species (EBS), along with many other biological species from around the world. There's a chart of these accepted species here.

Armillaria nabsnona mushroom buttonsSo we knew that there were ten NABS but as of 1994 we had names for only seven of them. No one had yet described NABS IX, NABS X, or NABS XI. In the fall of 1994, I was working at the Center for Forest Mycology Research at the USDA Forest Products Lab in Madison Wisconsin. Hal Burdsall, my boss, suggested I travel to the Olympic Peninsula in Washington State in search of these unnamed biological species, which we knew only from their mycelium-- we didn't know exactly what the fruiting bodies looked like. Of course I was thrilled to go, since the Olympic Rainforest is one of the wettest places in North America, receiving up to 200 inches of rain per year. Of course, to me rain=mushrooms. If you ever get the chance to go to the Olympic Peninsula, I suggest you GO!!!!

So how could I be sure to collect the right species of Armillaria? Since mating studies take several weeks in the lab, there's no way I could know in the field which species I was looking at. So I photographed, collected and cultured EVERY ARMILLARIA I SAW! This systematic approach proved to be extremely useful and allowed us to identify which of the specimens belonged to NABS IX.

Armillaria nabsnona type on Acer macrophyllum log Let me tell you about the first time I saw Armillaria nabsnona-- although of course I didn't know it at the time. I was in the Hoh Rain Forest, which is along the Hoh River on the west side of Mount Olympus in Olympic National Park. I was luck enough to stay in the VIP cabins right there on sight and earlier that morning I was awakened by a herd of Roosevelt Elk just outside my door. The mist was rising off the mountains, and it was a rare clear day, so I decided to take the trail through the moss covered maples. In front of me appeared a mass of several hundred Armillaria fruiting bodies on an old bigleaf maple (Acer macrophyllum) log (about 1 meter diameter) that had fallen across the trail. I noticed that this specimen looked very different from any of the others I had seen thus far. Needless to say I was very excited! I took about 10 pictures of it and examined it very closely in the field before I collected some of the specimens (enough for a type!) and returned to the cabin to make cultures from both the tissue of the fruiting body and from the spores. Just so you don't think I knew exactly what I was doing, this scene was repeated about 25 times while I was there...

After I returned to the Forest Products Lab I turned over my cultures and dried specimens to Mark Banik, who did an excellent job of determining which species I had collected. He also did some molecular biology work on the species and confirmed that I had indeed collected North American Biological Species IX. As it turns out, I had collected it about 5 times while I was there, and now that I can recognize it, I know it had been collected at the NAMA foray as well. So I had a confirmation of the species identification by both cultural and molecular biological methods, so all that was left to do was to formally describe the species. But what should we call it? Well we already knew it as NABS IX, and most species are named after an important character that distinguishes them from other related species. From my experience with the other NABS I had seen the confusion arising from the dual nomenclature-- the Roman numerals that designate the NABS along with the Latin name for the species. I had grown weary of remembering that NABS I was A. ostoyae, NABS II was A. gemina, NABS III was A. calvescens, NABS V was A. sinapina, NABS VI was A. mellea, and NABS VII was A. gallica. So we decided to make it easier on everyone and name the species for what we already knew about it. We called it Armillaria nabsnona, the specific epithet coming from NABS, the acronym for North American Biological Species, and nona meaning "ninth." You can see the entire text of that paper here.

Incidentally, that was a very productive trip for me. We were able to identify several of the other specimens I collected as A. ostoyae, A. sinapina, and A. gallica. We were also able to confirm the presence of NABS XI that Duncan Morrison had noted in British Columbia. We published this in Banik, Mark T., Thomas J. Volk, and Harold H. Burdsall, Jr. 1996. Armillaria species on the Olympic Peninsula of Washington state, including confirmation of North American biological species XI. MYCOLOGIA 88:492-496. Later, Banik and Burdsall confirmed that NABS XI is indeed conspecific with Armillaria cepistipes Velen. from Europe. NABS X is yet to be formally described.

So I hope you've learned something interesting about how a new fungal species can be described. It can be pretty exciting-- but it's actually not that difficult to discover a new species of fungus. There are about 70,000 described species of fungi, and that is estimated to be only about 5% of the species that actually exist in the world. The total number of species of fungi is estimated to be about 1.5 million. As a comparison there are only about 5000 species of birds in the whole world, 700 that regularly occur in North America. If you discover a new species of bird you are likely to make the front page of the New York Times. If you discover a new fungus you are lucky to make the back pages of Mycologia. Or you can put it on the internet like I've done here, where everyone can see it. :)

If you have anything to add, or if you have corrections or comments, please write to me at

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