How to handle indistinguishable symptoms caused by multiple desribed species

[Megachile]

This comes up a lot more in scales, leaf curl, and fungal leaf spots than with galls, which is why we haven't really discussed it so far and maybe isn't worth dealing with at all. But just to float the question, should we have some kind of infrastructure in place to accommodate cases where we know a symptom is caused by more than one described species, but there's no way to tell them apart in the field (ie without genetics or microscopy etc). At the moment I've done a couple of these as "undescribed" but that's not necessarily correct per se.