Favourite finds of today 17/10/22

I've spent most of the day combing through unidentified fungi in Costa Rica looking for anything which might be another unusual coprinoid. Some results were found:

https://www.inaturalist.org/projects/cryptic-fungi/journal/71387-search-completed-some-results

However more interesting for me were all the things I found along the way.

Myrmecopterula velohortorum

Observation 36167883 Image copyright: @sarahkuppert

I had never seen this before outside of the photos in the paper describing it ^[1] so this was a lucky find. Unfortunately the taxon doesn't exist on iNaturalist yet so for now it is just identified as Myrmecopterula (I don't know how long it takes for a curator request to be approved). This species was classified as Pterula velohortorum in 2014 ^[2] and reclassified under the novel genus Myrmecopterula in 2020 ^[1] however the old name is not in iNaturalist either and the species is largely unknown so this could be one of the first identifications of it on iNaturalist outside of the small number of observations of nests of Apterostigma. I suppose this raises the question of whether such an observation is better identified as belonging to the ants or belonging to the fungus. In this instance I would suggest fungus since only one ant is faintly visible in the shot however for mutualistic species such as this it would be nice if observations could be identified as both species to aid in the identification of them.

I only know anything about Myrmecopterula because I stumbled upon it whilst trying to research the potential association between some Leucocoprinus species and leaf cutter ants. The most commonly farmed ant fungi was reclassified as Leucoagaricus gongylophorus and I was unable to find much definitive information (which wasn't out of date) on any current Leucocoprinus species which are farmed. However in the process I ended up writing the Wikipedia pages for the Myrmecopterula genus and the three named species and learning about that instead.

M. velohortorum is a fungus cultivated by ants belonging to the Apterostigma dentigerum subclade. The nests are suspended under logs or from trees and covered by a mycelial veil woven from the fungus. The nests only have one hole to enter and exit which is seen to the left of this image complete with an ant in the doorway. So the identity of this species is certain (barring any future discoveries or classifications of related species, there are some species of Myrmecopterula that have yet to be formally classified).

M. nudihortorum is similar but it is not found cultivated in hanging gardens but rather in shallow recesses in the ground. It also is not covered by a mycelial veil so the two are easily distinguished and in turn this distinction helps identify the ants. Neither species has been observed to produce fertile mushrooms and they are therefore thought to be dependent on the ants.

Myrmecopterula moniliformis

This related species has been shown to produce both fertile and infertile forms and is hypothesized to have escaped cultivation in the past. The fertile fruiting bodies may resemble the fine coral shapes of Pterula species whilst the infertile ones give it the specific epithet moniliformis meaning bead or necklace shaped. Again, barring further discoveries and reclassifications of unnamed Myrmecopterula species this is a relatively simple mushroom to identify but it is simply fairly unknown.

Observation 97520272 Image copyright: @ale_vasquez

Observation 31675982 Image copyright: @andreagreening

These two observations seem certain and the first even appears to be growing from an ant mound. This species is observed growing from abandoned ant mounds and is thought to play a role in breaking down the residual matter left from a dead nest, although there is some speculation that it may also grow parasitically on living ones. Unlike the two other named species in this genus, M. moniliformis is not dependent on the ants and may grow from the ground with or without ant nests being present.

The third observation I identified as Myrmecopterula moniliformis is less certain.

Observation 108207690 Image copyright: @rkostecke

The trouble is that the same area which hosts Myrmecopterula also appears to have a startling diversity of Xylaria species, far more than I am used to in the non tropical habitat that I call home. The shape of the sterile form of M. moniliformis can appear similar to some of these such as Observation 119753999 and Observation 108775547 which appear more likely to be Xylaria owing to the apparent black colouration where the white surface is scraped off and the hint of black towards the stem base. Whereas when the surface of M. moniliformis is damaged it seems to show a brownish-red colour and sometimes exhibits the same towards the base. The white, chalky surface is otherwise similar so when M. moniliformis is not exhibiting its chaotic branching bead like structure and is in a more simple form it may be easier to confuse. However this particular observation looks very similar to the exceptionally picturesque one made by @teodoro_chivatabedoya only without additional beading on top of it.

It seems possible that a search for identifications of Xylaria species in these regions may yield some misidentified specimens of M. moniliformis owing to it not being commonly known.

Finally, an additional obscure species (and one which is new to me) that I potentially found during this online fungal foray was Xylaria compuncta. This species is evidently rather uncommon and is suggested for Red List status. There are not many images online for it and iNaturalist only had five or six observations for it at the start of the day, none of which are confirmed by multiple parties. However I kept noticing strange ball like mushrooms on wood during my browsing and could not think what they might be. Cryptoporus volvatus, the fungus associated with bark beetles, was the only thing that immediately came to mind and perhaps it does explain some of them.

By chance I came upon Xylaria compuncta as a potential ID when using the taxonomy browser to compare Xylaria species and it seemed possible owing to the variety of Xylaria in the area and the black colouration some displayed. It is however unclear to me how these species look when very mature or very immature and so, for now, I have suggested an identification of Xylaria compuncta for a range of similarish looking forms which I think could reasonably represent young and old specimens. I do not think all are correct but since Xylaria compuncta is an important species to better document given the proposed Red List status, and since these observations were otherwise just languishing in Kingdom Fungi it seemed prudent to collect them together for comparison. All bear some similarity to the observations already identified as belonging to this species however since none of those are confirmed either...

Mushroom Observer has three observations for this species under the synonym Sarcoxylon compunctum but there is some variation in the appearance of these too.

https://mushroomobserver.org/observations?pattern=Sarcoxylon+compunctum

I will try to do some reading on this species, maybe put together a wikipedia page for it in time to compile all the sources and see if I can nail down or eliminate any of these observations. However I would very much welcome others to check my identifications on these and see if they can rule any out as another species that I am yet unaware of.

https://www.inaturalist.org/identifications?user_id=mycomutant&taxon_id=919780

^{[1] 'Reclassification of Pterulaceae Corner (Basidiomycota: Agaricales) introducing the ant-associated genus Myrmecopterula gen. nov., Phaeopterula Henn. and the corticioid Radulomycetaceae fam. nov.'
https://imafungus.biomedcentral.com/articles/10.1186/s43008-019-0022-6}

^{[2] Phylogenetic Placement of an Unusual Coral Mushroom Challenges the Classic Hypothesis of Strict Coevolution in the Apterostigma Pilosum Group Ant–fungus Mutualism
https://onlinelibrary.wiley.com/doi/10.1111/j.1558-5646.2009.00697.x}

Publicado el 17 de octubre de 2022 por mycomutant