Xylaria polymorpha seems to be a somewhat commonly observed species around europe and eastern north america. However, it seems from some google searches that there are several Xylaria species that all look identical to polymorpha, requiring microscopic views of spores to differentiate them. I was wondering what the standard approach for identifications like this are. It would make sense to me if people were IDing as “Xylaria cf. polymorpha”, but iNat has no cf. feature. Should the IDs of Xylaria observations without spores be counted as incorrect, and moved back to genus, or are they considered ok, because it would be difficult to properly ID them to species anyways?
It would need a Xylaria sp. id without a disagreement (if there’s no subgenuses, etc.) plus a comment for observer so they could change the id, same situation is e.g. with Polygonum or Alchemilla. If there’re RG obs you sure are not I’d click on “can be improved” and tag iders in a comment with explanation.
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So the large majority of observations would best be sent back to genus, without the presence of some sort of complex or other similar taxon, then. Sounds unfortunate, but I guess that’s how it is with hard-to-ID genera
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There are a lot of them here in my area and I will only ID them to the genus level. I have no way of determining species and just accept that genus is far as I can go. I still shoot them anyway as I think they are pretty cool :)
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That is why I always vote for creating complexes when possible. It is much more acceptable for the users to get name of the complex than genus instead of a species. By the way, complex question is already rife not only for X. polymorpha, but also for Flammulina velutipes, Nectria cinnabarina, Paxillus involutus and probably more fungal species, but these come to my mind first, as I encounter them most frequently.
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You always can vote for adding a species complex.
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Where and how?
Adding a flag to the genus.
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iNat appropriately sets criteria for the use of the pseudorank ‘complex’ to one that is recognized in the literature and constitutes a monophyletic group …
https://www.inaturalist.org/pages/curator+guide#complexes
Species explicitly assigned in the literature to the Xylaria polymorpha complex/aggregate (and number of iNat observations) are …
Xylaria scruposa (1), atropshaerica (0), polymoprha (3700), schweinitzii (6) haemorrhoidalis (0), globosa (8)
There will be a few other species in the same clade as well.
I suspect what is being asked for here does not comply with the criteria. We should not use the pseduo-rank ‘complex’ for “all the species that look similar to …”. In my opinion that is a slippery slope. Far better to drop back to genus for these identifications and restrict species complex for monophyletic groups. A more appropriate solution is something like a common name that could resolve to several species. That would require a fundamental change in the iNat model.
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I found a key for Xylaria of NA. Seems there’s 20 species with the same growth medium as X. polymorpha, none of which can be reliably distinguished with macroscopic characteristics. http://www.cybertruffle.org.uk/cyberliber/59575/0026/0085.htm
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Actually the iNat model would easily accommodate that right now, if I’m understanding your suggestion here. It just might not conform with the informal policy in some groups to have a unique common name for each taxon, and the more formal policy not to “invent” common names on iNaturalist.
That key wont help you. That is an (old) key to the genus Xylaria in North America and is not specifically about the Xylaria polymorpha complex. It refers to just two species in that complex, which includes X formosana, X. atrosphaerica, X. cf. glebulosa, X. globosa, X. haemorrhoidalis, X. ophiopoda, X. polymorpha, X. schweinitzii, X. scruposa
doi:10.1016/j.ympev.2009.12.015
Yes it could accommodate something - but not in the sense of a normalised database structure
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I think that that just further proves that they’re not IDable to species without using a microscope, which is all I’m really looking for. If you have any literature with an updated key, or really just any proof in literature of “X. cf polymorpha can’t go to species”, I’ll be happy to put that in my comments when I disagree with X. polymorpha IDs
Well… aren’t those creepy! But, so apropos for Halloween. 
♂.
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@daffydork how do you know that it’s that species? This thread is mostly about how Xylaria cannot be IDed to species, and I don’t see any microscopic shore spots in yours
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I was with a friend who’s pretty in to fungi. they said that they were pretty sure that that was what it was, I’m not as knowledgeable as them, so I just went with what they thought. 
Yeah, the species is kind of used as a general name for all of the similar species. Which, for simply saying “hey I recognize this as x” is fine. But on iNat, we have no “looks like this species that kind of represents this whole group” feature
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