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Spores: (6) 7-14 (15) x (5) 6-8 (9) µm. Ellipsoid, amygaldiform or subglobose. Hyaline, smooth and with a large greenish oil droplet/guttule inside and a capped germ pore. Dextrinoid, congophilous, cyanophilous, metachromatic in Cresyl blue with pinkish purple inner wall. Very slight pinkish colour in 1% Aniline blue in lactic acid. Pinkish colour to inner spore and yellowish tone to wall observed in 5% KOH mount becoming more noticeable in 10%.

Guttules were mostly single, some double or triple. The largest single ones observed measured: 3-4 x 3-4.5 µm.

Dried mushroom cap showed a very slight pinkish tone when 5% KOH was applied, though mostly just bleached. 10% FeSO4 resulted in similar bleaching but no colouration was noted.

Leucocoprinus species sent to me from a Reddit user in the UK. Growing in a potted Aspidistra plant inside. Presumably Aspidistra elatior.

https://www.reddit.com/r/mycology/comments/151e3sn/id_for_these_fellas_uk/

Spore prints and a number of dried specimens were received - the gills of which had discoloured to such a greenish grey colour that they initially looked like they could be moldy, since they had rehydrated slightly in the mail. Upon closer inspection however this was just discolouration, or possibly was the result of the greenish guttules/oil droplets inside the spores. The spore print appeared whitish on the black paper but the slides with gill sections mounted showed a slightly greenish grey colour where spores were spilling out, visible with the naked eye. So perhaps enough spore mass in a print would have the same tone.

Macroscopically the mushrooms appear similar to Leucocoprinus cepistipes with the distinctive looking shape of the immature mushrooms complete with the clear exudation.

I have seen a similar greenish grey gill discolouration in observations before, see here:

https://www.inaturalist.org/observations/20082876

https://www.inaturalist.org/observations/32393475

Whereas other times a more reddish pink, brownish or yellowish tone is present. I'm not clear if there is any distinction between these or if it just represents different stages of discolouration.

Microscopically however the spores were far larger than those noted in descriptions of L. cepistipes. A size of (6) 7-14 (15) x (5) 6-8 (9) µm was observed from spores spilling out of a gill section crushed under the cover glass. From the spore print however a smaller size was observed of 7-11 x 6-7 µm. The larger spores were immediately obvious upon looking at a gill section and were not just outliers.

Flora Agaricina Neerlandica vol. 5 gives a spore size for L. cepistipes of 7.5 - 13 x 6-8 µm so this would seem out of that range.

I have also observed this with L. ianthinus where a gill section results in a larger spore size reading than from the print. So it appears that measuring the spore size of Leucocoprinus species from prints may not be reliable. I have not read anything to the effect of spore prints being less reliable than gill section mounts for measuring spore size. Mushroom Expert seems to note the opposite, mentioning that immature spores may be seen with a gill mount. Spores that appeared obviously immature and undeveloped weren't included in my measurements, but seemed fewer than the large spores anyway. Most of the spores with a measurment of 5µm were closer to spherical and either 5x5 or 6x5. They appeared fully formed though rather than immature.

I am speculating that perhaps Leucocoprinus species retain more of the large spores when they are found outside of high humidity, tropical environments as a larger buller's drop would need to form in order to release larger spores. However I've never looked for this phenomenon in common, native garden mushrooms so will have to see if I record the same thing there.

Comparing the photos of the mushrooms and the size of the spores to the 80 odd species of Leucocoprinus for which I have adequate information I cannot find a direct match. My best guess currently is that this may be something that has been described as a variant or form of L. cepistipes. So I'm going to try and get the description for Leucocoprinus cepistipes f. macrosporus Migl. to see if this may match and explain the larger spores.

They appear similar to this observation from New Zealand, also found in an Aspidistra plant so perhaps the plant may point to an origin for this species/variant. Will need to look for more observations with these plants.

https://www.inaturalist.org/observations/2620120