As well as the discussions linked by @upupa-epops, When should a genus be subdivided? was another recent thread along similar lines. I added a comment there sharing the rules-of-thumb I have used.
https://forum.inaturalist.org/t/when-should-a-genus-be-subdivided/71486/19?u=rupertclayton
Basically:
- Only add an infrageneric taxonomy if you’re aware of most recent research for the genus.
- Don’t bother adding infrageneric taxonomy where it would provide little value for iNat users, such as for genera with only a few species.
- Use an infrageneric taxonomy that is supported by phylogeny if one is available.
- If there is strong evidence that an infrageneric taxonomy conflicts with phylogeny, think carefully about the likely disruption that will be caused once better evidence means we need to revise it. It’s fine to leave the genus undivided for now.
- If there is active disagreement about infrageneric taxonomy by researchers in the area, it may be best to wait for consensus to appear.
- Add a flag with details of your proposed changes and solicit input from the most frequent/knowledgable identifiers.