The issue(s) with Incertae sedis taxa

I’m not sure whether or not to make a feature request about this, so I thought it might be better to generate a discussion first, since I’ve not seen it mentioned. It may be a bit pedantic, but it’s something I’ve had on my mind for a while.

Taxonomy is a messy thing and it’s always changing for many groups. However, some groups may not receive attention for centuries and waiting for certain things to change isn’t always realistic. During revisions of certain taxa, authors will often move a taxon out of the parent taxon and into an Incertae sedis group when it clearly does not belong in the original parent taxon, but the author has not investigated or is unsure of its proper placement. These Incertae sedis groups can often become widely adopted and referenced in later works as consensus builds for such changes. This usually isn’t too much of an issue on iNat—from a technical standpoint—since genera and wider can be placed under any higher taxon (we usually refer to it as “ungrafted” but with Incertae sedis taxa it’s the only option—say a genus being placed under a family). However, this gets very tricky when we have an Incertae sedis group within a tribe. I’ll use a leafhopper Incertae sedis species group as an example, since my interest is in Auchenorrhyncha.

The Australian species evansi is currently placed in species group Erythroneurini-Incertae sedis, the placement for a number of species in the tribe. My current solution to this is to use the most recently published synonym in order to reduce clutter. An alternative I thought of was to use the type-genus name (also the originally published name for this species) and place it under the tribe instead of under the genus Erythroneura. I thought this might be more confusing however, especially as Erythroneura is technically geographically confined to one continent and the conflicting information may confuse users.

This is an easy thing to address in BugGuide, where it is possible to create Incertae sedis pages (see here). This comes up frequently when it comes to subgenera, tribes, and other broader groups as well. I think it would be great if iNat was able to address this in some way with a feature, but I’m not sure exactly what the feature itself would consist of (ideally an “add Incertae sedis” group option would be great, where it would automatically include the name of the parent taxon depending on where you create the new taxon). I’m curious to hear how other curators of the iNat taxonomy address this when it becomes an issue of keeping the site up-to-date.

In addition to the technical taxonomic issues is the general issue of clutter created by ungrafted taxa. I stated earlier that this isn’t too much of an issue from a technical standpoint, but iNat isn’t really a taxonomic database and making things easily navigable for users seems to be of higher priority. As an example of the mess we end up with see all of the Incertae sedis genera of Flatidae. Having multiple taxonomic ranks under a single taxon can look rather confusing and I think this should be a simply amendable problem. Also, when new taxa are imported by users, they are often ungrafted and they can get lost in these long lists of Incertae sedis taxa if no one flags them. I see that some curators have tried dealing with this in the past (see here), but without standardisation that too makes things rather messy and I don’t think it’s technically permitted to make such a taxon anyway (as with undescribed taxa, which some curators add although it’s technically against the site rules).

In order to reduce this kind of clutter, it would be great if such groups could be collapsed under one group, regardless of what that group is called in my opinion. I’m sure there may be an argument that this group would be provisional or polyphyletic—however I think this is the way a lot of taxonomy works (we have soooo many polyphyletic groups). If it is published and accepted taxonomy (especially by major databases and leading experts) AND it’s something that can help reduce confusion for users of the site (as long as a hover pop-up explains what “Incertae sedis” means) I think it’s certainly a change worth considering.

I’d love to hear the community’s thoughts on this, including if you aren’t a curator!

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See regarding a species without a genus.

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