Large genera with formal species-groups

There are some large insect genera (large number of species) that I frequently identify that are formally further subdivided not into subgenera but instead into formal species groups. They are named by a species within the group, usually the first-described species. They are as rigorously defined as the genus itself, intended to group closely related species (monophyly), and are published in peer-reviewed literature as well as our taxonomic authorities.

It’d be useful to have these species-group subdivisions for IDs instead of having tough species calls being left at the giant genus. There is no “species group” taxon in iNat.

Inside some of these formal species groups are clusters of a small number of species that are externally identical in photos and most iNat observations of them could be identified only to the cluster. Some of these clusters are monophyletic and would seem to qualify for the Complex rank; the others would seem to not deserve any special taxon here. This provides another reason for including the formal species groups but at a higher rank than Complex.

Would it be acceptable to include these species-groups and place them at the Section rank with the two-word species group name?


“Complex” and “species group” are often used interchangeably in the literature, so that would really be the best place for them. There shouldn’t be any groups that include both a “complex” and “species group” as separate concepts.

I’ll note, though, that the full published name for the group is supposed to be in the form of Genus species group or Genus species complex (often but not always with a hyphen after the specific epithet). It isn’t acceptable anywhere in the literature to use just the nominate species’ name as that’s a completely different concept (it would be good to have this officially amended at least for insect groups).

The same issue of formality occurs throughout higher molluscan taxonomy (officially using cohort, subcohort, and informal clades but represented as the closest equivalent by our authority, WoRMS). Sometimes taxonomy doesn’t fit into the boxes that sites try to force it into since many groups can’t be understood as well using just the simple and neat taxa.

I would not advise using that Section rank here as that particular taxon is unique to botany (a Section in zoology is very differently defined and occurs between Order and Family ranks). Insect taxonomy doesn’t have an option of a Section rank below genus.


If the genus is divided in to “species groups” instead of “subgenera” (rather than including both taxonomic levels), is there any reason to avoid using “Genus species group” at iNat’s subgenus level? Would the system permit names like that for subgenera?

I would think against doing that as some taxonomic groups (esp. certain insects, I want to say this includes a number of bees) are divided into both subgenera and species groups. Subgenus has a somewhat particular definition as an official taxonomic rank whereas the likes of “species group” and “genus group” aren’t quite so official

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Yes, some insect subgenera may have species groups, and some species groups have Complexes in the sense of the iNat rank (a closely related group of species that are especially difficult to distinguish). So it seems wise to avoid iNat’s Subgenus and Complex ranks for formal species groups.

Of current iNat rank options, only Section and Subsection remain, and they are conveniently positioned between Subgenus and Complex. Like @jonathan142, so far I haven’t seen either rank used formally in insect literature between genus and species. So these would seem to be the best options to avoid collisions with other rank needs, with Section preferred over Subsection. The downside of seeing “Section” with meaning “species group” would be outmatched by the upside of being able to use the taxa for user and community IDs.

If a new rank of “species group” could be added to iNat’s taxonomy, right above Complex, that would be even better.

My impression has been that a complex refers to a very small number of very closely related species for which the lines between species are fuzzy for some reason, either due to hybridization or difficulty in identification. Whereas species group could refer to any monophyletic group of species below subgenus (or genus in genera without subgenera). So I do think it would be useful to have an official species group rank between subgenus and complex.

I am not sure how apply it in relevant cases I can think of though (such as Condylostylus and a couple hover fly genera) because the species group may be super useful for identifying but only casually mentioned in papers, or named formally in some papers and informally in others. The same issue applies for complexes though so maybe this is a general issue more appropriate for another thread. Your case seems more clear-cut.

I agree, we should not be commandeering formally defined taxonomic ranks (in either or both nomenclatural codes) to use for informal groups. I believe that the informal Complex rank was added to serve that purpose instead, and there is no reason it can’t mean somewhat different things in different groups, as long as it follows the Curator Guide:

Species Complexes

As of January 2019, " complex ", a taxonomic rank between genus and species, may be used (more specifically, between subsection and species). Species sometimes intergrade and there are places on the tree of life where adding hard range map boundaries is arbitrary and/or identification to species level is often not possible. Species complex should be used sparingly (only when necessary and helpful) and with the following criteria:

  • Species complex is monophyletic (i.e. sibling groups of species)
  • Complex is recognized in the literature
  • A named subgenus, section, or series does not already exist for the group
  • If a name is not established in the literature, use the earliest published species name for the name of the complex
  • Don’t use compound names, such as Pantherophis alleghaniensis-spiloides, as there may be numerous species in the group

Examples include:

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So, just to clarify, is suggesting a species complex acceptable? Often times with fungi species complexes come up. Will never be IDed further than that without microscopy. I personally want to call a lot of things “Amanita bisporigera” or “Cantharellus cibarius” but not quite sure what the etiquette is there.
Seeing things being restricted to genus level IDs like that seems a shame.

I occasionally see comments of “or one of that group” attached to a species id… That is fine, anyone using the data is likely aware of the issues with that taxa. iNat is less about documenting to species level than it is about documenting what you see, and if what is seen can only be id’d to genus or family, then that is ok! It still adds value to comment as to range of possibilities for species


Certainly! Best way is to go to the iNat taxon page for the genus (or appropriate subdivision thereof) and Flag for Curation. Make the flag reason something short and to the point, like “Create Drosophila melanogaster Complex taxon.” After hitting “Flag It,” return to the flag using the link provided, and leave a more detailed comment about the proposal, why it’s needed, what species would be included, etc. Try to address all of the criteria listed above from the Curator Guide. To the extent the proposal doesn’t meet those criteria, make your best case for why the complex should be created anyway. And finally, to get faster attention, @ tag the usernames of any other iNat users you know who would be knowledgeable or interested in the proposed complex.


There’s probably a dozen fungi complexes I’d like to see, but I’ll try to start with some of the more repeat offenders ;)
I see a lot of things clearly “Amanita bisporigera” complex, but it often gets left as Amanita because people overthink the exact species. So, just to clarify, in that situation, where it’s definitely a species listed already, would I just continue to use the species level taxa that the site already has (Amanita bisporigera), or would you make a new one to further specify named (Amanita bisporigera [complex]), or something along those lines?
Thanks folks.

This application seems to disagree with this definition of a complex that I was given when the complex option was created, and with “Species sometimes intergrade and there are places on the tree of life where adding hard range map boundaries is arbitrary and/or identification to species level is often not possible.” Species groups can have species where there is no doubt that they are valid species, and are easily separable with a microscope. If we go with this, should the above definition be broadened?

What would we do in a case like this?

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I think this can be true of complexes under the current guidance too, though you are right, it could be clarified. I read the sentence you quoted as covering three example “and/or” situations:

  • Species sometimes intergrade
  • there are places on the tree of life where adding hard range map boundaries is arbitrary
  • identification to species level is often not possible

Identifications of species Amanita bisporigera should only be used to suggest that single species. If you are wanting to use it to suggest “Amanita bisporigera or similar Amanita species,” then for now you should be identifying it as genus Amanita (with comment as needed), and proposing the creation of a new Amanita bisporigera complex taxon. Complexes are named after one of their component species, but they are not the same as the species taxon.


Okie doke!