the genus xylaria hypoxilon is a mainly american species of fungus that has been miss id’ed multiple times as the regular genus. most of the observations that i have been seeing are not just xylaria hypoxilon but xylaria hypoxilon complex. there is a huge difference!
there is a difference in shape for the complex, but for regular hypoxilon the shape is consistent
complex xylaria hypoxilon has more variation than regular hypoxilon. regular hypoxion is only 2-3 black antlers topped with white powder.
Your morphological differentiations are doubtful. For example, the epitype designated by Stadler et al. clearly shows specimens with less or more antlers (Stadler et al, 2014). How have you found these differential characters?
I would like to add that Xylaria hypoxylon is originally described from Europe and therefore describing it as a mainly American species can be misleading. It seems that it’s at least present in North America but without more in depth morphological and genetic studies it’s difficult to tell what is its true geographical extent.
For the observations you linked: 111873140: I agree it’s not Xylaria hypoxylon as the teleomorphic and anamorphic stages are morphologically different and it’s geographically isolated from the type. 111897681: Those are probably old specimens. It’s common to find them opened like this as the interior disappear quicker than the exterior. 111414254: I don’t know if these criteria are differential. It could also be specific variation. Peršoh et al. don’t use the ridges for differentiation (Peršoh et al., 2009). 108768950: This is possibly another species but I’m don’t want to affirm without the teleomorph. It’s distant from the type so I would prefer this option. 109141214: This one is definitely not Xylaria hypoxylon. Ecology and teleomorphic stage doesn’t fit the species.
Yes, that’s the case for many fungal species. The problem is that it needs to be backed by studies and it’s currently not really the case for Xylaria hypoxylon. The studies around this complex are still just preliminary studies.
i have studied xylaria hypoxilon since i started inaturalist in 2019. thank you for the information about the identifications though! i have learned these characteristics by identifying xylaria hypoxilon and studying what the forms look like. so that’s how i found the characteristic differences, and i am okay with being wrong in my identifying. it just means i have a lot to learn!
-sageost
You would have to show that the same individual consistently produces the same differential character each time it fruits. To take the antler analogy: think of white-tailed deer. Why don’t we recognize separate species for spike, forkhorn, six-point, eight-point, and so forth? Because we know that the same buck can be a spike one year, a forkhorn another year, and so forth. And because we know that the same doe can produce male fawns who grow up to have different numbers of points.