The Reclassification of the Inkcaps: What's in a name?
The spring mushroom season is upon us again, and I'm faced with a choice of writing about St George's Mushrooms, which I've done before (and they're late this year, and there doesn't seem to be very many of them after last year's bumper crop) and morels, which continue to evade me. So I'm going to write about something else, and the obvious choice presented itself to me a couple of weeks ago in the form of this rather beautiful little mushroom which these days belongs to a genus called "Parasola." I'm not certain of the species, there being quite a few similar members of the genus, none of which are of much interest from a foraging point of view, and which can't easily be distinguished without miscroscopy anyway. However, in terms of fungal taxonomy - the ongoing re-classification of mushrooms as widespread genetic testing reveals the true evolutionary story of what is related to what - there is a tale to be told here.
Picture: Parasola sp.
Until very recently, we would just have called this an inkcap, and by that we'd have meant it was a member of the genus Coprinus, in the family Coprinaceae. For those readers unfamiliar with the intricacies of taxonomic classification, "family" is the most important taxonomic level above "genus", and "genus" is the level immediately above individual species. For each genus, there is something known as a "type species." The type species is the species upon which the whole genus is based, and for this reason whenever a genus has to be split up (because we've discovered that it contains two or more different groupings which shouldn't have been put together in the first place), the group containing the type species gets to keep the genus name, and the others are placed elsewhere (either in other genera that already existed, or in news ones invented for specially for them). Which is where this story gets interesting, because it turned out that it was the type species of the genus Coprinus that didn't belong there.
That type species should be very familiar to foragers of fungi. I believe it was the first wild species I ever self-identified and consumed, it's extremely common and one of the very few species that is almost impossible for a beginner to get wrong, as well as being good to eat. Its latin name is (still) Coprinus comatus, and it goes by the common name of "Shaggy Inkcap" or "Lawyers Wig" or "Shaggy Mane".
Picture: Shaggy Inkcap (Coprinus comatus)
There is no mystery why this is called an "inkcap" either - the caps deliquesse, which is a technical term meaning "disintegrates into liquid", in this case a very black liquid consisting of the fungus' spores and which was once actually used as ink. For this reason you have to eat them the day you pick them. If you don't then you'll just end up with ink all over the inside of your fridge.
Anyway...back to my tale. Until recently, there were a large number of species in the genus Coprinus, in the family Coprinaceae. They all have this characteristic tendency to deliquesse, after turning black. But much to the surprise of nearly everybody, when mycologists tested the genes of the shaggy inkcap, it turned out that this species does not belong in the same family as the rest of the inkcaps. Instead, we now know that it is a member of the family Agariceae, which takes its name from the genus Agaricus. It turned out to be a close cousin of the mushrooms we buy in the shops (Agaricus bisporus), as well as field mushrooms (Agaricus campestris.) And it's not the only surprising new inclusion either. Perhaps even more strangely, many of the puffballs, which look so utterly different, are also now known to belong to this family.
So what happens to the inkcaps when the King of the Inkcaps turns out not to be an inkcap at all? Well, the common names are staying the same for now - we still call them all "inkcaps." But the family "Coprinaceae" has ceased to exist, and the genus "Coprinus" is now tiny, containing just the shaggy inkcap and a handful of its relatives globally. There are no others in the UK. The rest of the species which previously belonged to the genus Coprinus have been relocated to Coprinopsis, Coprinella and Parasola, all of which have been relocated to the family Psathyrellaceae, roughly doubling its size (the existing members of this family, mainly belonging to the large and complex genus Psathyrella, are known for their brittle stems rather than their tendency to turn into an inky mess.)
"Inkcap", therefore, has ceased to be a term that has any scientific or genuine taxonomic meaning.
Science marches gloriously on! Language languishes.