Identifying a mystery fungus – Julie Lane

On 11th December whilst walking in Salcey Forest I saw a toadstool that was a bit different to others I had seen around the place. On closer inspection I realised that it was attracting large numbers of gnats (probably a type of fungus gnat). I took some photos and sent them to a very helpful lady at Bucks Fungus Group.

Penny Cullington very kindly had a go at identifying several fungi that I have photographed but she always makes it clear that she cannot identify a fungus from a photo and would need the actual specimen to make a definite identification. I am always rather loath to uproot anything as even a toadstool, which is only the fruiting body of the fungal mycelia underground, is still providing a habitat for something even if it’s only a tiny gnat!

Penny was interested in the darker spots around the rim of the cap and thought that it might be something rather rare, as there have been quite a few unusual fungi around this year, but she needed to know when the photo was taken, what trees were nearby, did it have gills or spores and if gills what colour they were, etc. After providing her with this information, she was still only guessing so on our next visit to Salcey I finally relented, uprooted it and took it home.

Once I had harvested the toadstool you could see the white spores actually tucked inside the gills of the cap (see below).  Interestingly, I also noticed two little parasitic wasps on the cap which I assume were parasites of the gnat larvae (?) – another link in the chain of woodland life.

On Penny’s advice I carried out the following two procedures.

Sporeprint: Cut off the cap from the stem at the top. Set the cap gills-down on a piece of dark paper and cover it with a pot / bowl/ whatever to keep air currents out and leave it overnight somewhere cool (not in the fridge!). Next day, check to see if you have a thick deposit (we’re guessing it’s going to be pale cream to white, hence putting it on dark paper otherwise you won’t be able to see it!)

Drying: Now cut the cap into quarters and, together with the stem, put it spread out a bit gills up in the airing cupboard over the top of the hot water tank is ideal. The air needs to circulate around it so it’s best put on wire mesh – something like a cake-cooling rack as long as it’s not going to fall through! Then forget about it till after Christmas!

I managed to get a lovely sporeprint. I then cut it all up and dried it as requested and sent it to Penny.

Disappointingly, on receiving the sporeprint with its white spores and the dried material Penny now thinks it is most likely to be Clitocybe geotropa, the very common Trooping Funnel, and not the Clitocybe alexandri (now Clitopaxillus alexandri) which has only been recorded a few times in the country. She still says that she might send it off for DNA sequencing which is the next step for a definite diagnosis but I doubt that will change anything.

To be honest, it was what I suspected all along so I wasn’t surprised but I did find the whole process fascinating, from seeing the gnats swarming round the toadstool, to the process of getting a sporeprint and the final drying of the toadstool in my partner’s airing cupboard!! I will definitely try the sporeprints again in the future but still baulk at harvesting too many toadstools as they look so fabulous nestled amongst the leaf litter where they should be.

With many thanks for the help and advice from Penny Cullington of the Bucks Fungus Group. She’s the Secretary of the group and also the county recorder for fungi, so if you’d like more information about the group and its activities visit their website at www.bucksfungusgroup.org.uk/index.html.

Julie Lane
January 2021