by hyphoderma » Jul 27, 2013 2:26 am
Hi all. Wonderful thread that I stumbled upon. I'm one of the culprits behind the name change (I'm Dan, not Drew, the other culprit). People keep asking for a simple explanation, and I keep failing at that. The simplest explanation I can come up with is this: if you follow the "code" (the code that governs the naming of plants and fungi) and you know how these species are related (which we only just found out), you inevitably wind up with Pseudogymnoascus destructans. To be honest, when we first saw the DNA results that laid that out, we were shocked. Then annoyed, because who wants to be the guy who has to promote "Pseudogymnoascus"? Geomyces is such a lovely name: soil fungus. It's simple, and says it all. But sadly, it wasn't meant to be.
Two years ago I gave a talk and told people the name for this fungus would most likely be Pseudogymnoascus destructans in the future. I said this because at the time, sexual names (teleomorphs) took precedence over asexual names (anamorphs). That's the way it's always been, and it seemed inevitable since Pseudogymnoascus was likely the sexual stage of the fungus. However, the something amazing came along: after centuries of thinking it was ok to give one species two different names, one for the sexual stage and one for the asexual stage, mycologists voted for "one fungus, one name". It was a huge break through, and a huge mess. Things would be straightened out, but it would take a while. In the case of Geomyces all was wonderfully clear: Geomyces was the older name, and so it won. Cheers went up throughout the land! We'd never have to worry about Pseudogymnoascus ever again!
And then comes the second part of the story. Drew Minnis, my college and closet genius, pointed out that no one had ever sequenced DNA from the "type" of genus Geomyces. The type of a genus is the species that defines the genus, in the same way that a "type specimen" defines a species. The type of Geomyces was designated by people who really knew what they were doing: Sigler & Carmichael in Mycotaxon 4: 376. 1976. These people know Geomyces. They chose the species Geomcyes auratus and choose a culture collected by Traaen in Norway in 1914 as the representative. This was a logical choice for many reasons that I won't get into. When David Blehert, Andrea Gargas, Tom Volk, Marie Trest and Martha Christensen named the fungus "Geomcyes destructans", that generally fit because the morphology (shape) of the spore producing structures all looked the same in this group. Without DNA data, there was no reason to think there were any problems with Geomyces.
The problems became apparent when Drew sequenced genes from Geomyces auratus. Although everything in this group made spores in a similar fashion, this particular species was different, based on DNA. Way different. There was no way you could, given current scientific standards, lump Geomyces auratus and G. destructans in the same genus. And based on precidence, "true" Geomyces was clearly G. auratus. Everything else in the crown group needed a name, and the oldest name was Pseudogymnoascus. No easy way to avoid it, there it was. Pseudogymnoascus destructans. Same fungus, sillier name. But at least it's still pretty easy to say P.d. And, if you still say Geomyces destructans, everyone will still know what you're talking about anyway.
The up side of all of this? We know finally know how all these species are related, and can figure out which ones are close to P.d., and which ones are far away. The reason we really want to do this is for genetic comparisons so we can figure out how P.d. kills bats at a molecular level, when close relatives are benign. The story in North America isn't too interesting (nothing really super close to P.d.), but now that we've got the framework, we're very interested to plug in species from Europe and Asia, as well as the southern hemisphere. We think that's where the really interesting story will be. But that's for next post, since this one is already too long.
Best,
Dan Lindner