We had a lengthy debate about complexes elsewhere on the forum a while back, and it was brough up that the Curator Guide is very specific about what “Complex” is to be used for, and it absolutely does need to be recognized and named in literature to be added, and it needs to be defended in the literature as a monophyletic grouping:
https://www.inaturalist.org/pages/curator+guide#complexes
It might not be an official rank according to ICZN, but iNat is pretty strict about its use.
Yes, there is a feature request open to add “species group” as a taxonomic rank, as this is used in the literature for pretty much all large insect genera. Staff’s suggestion on that thread was
So iNat’s “section” and MONA’s “species groups” are, at least for now, being treated as synonymous. If a “Complex” is meant to be a “group of similar or indistinguishable species”, then the MONA “species groups” definitely don’t align well to that concept. There are cases where oddball species are in monotypic “groups”, there are cases where the members of a species group are unified by DNA/genitalia similarities and are extremely easy to differentiate based on external appearance, etc. At least for moths, current practice is to coopt “Section” to mean “Species Group” of the literature, and to reserve “Complex” for specific cases where a couple of very closely related species provide identification difficulty. The Curator Guide does say to use Complexes “sparingly (only when necessary and helpful)”, while species-groups are, honestly, not always helpful to have in the iNat taxonomy, and have been applied across-the-board to some large genera in the literature.
Here is the original full discussion about “Complexes” from last time this debate happened.
I guess tl;dr the rank is called “Section” on iNat because the botanists got to it first, and now the entomologists who use “Species Groups” are stuck pretending that it says “Species Group” because staff doesn’t want to add an analogous rank for us. lol