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:


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!

I’ve been meaning to weigh in on this for a while, but keep forgetting to. I believe it is a much-needed feature to incorporate species groups into iNat.

It sometimes occurs in Cicadellidae that there are species complexes within species groups. To work around this in iNat taxonomy, I’ve resorted to using the botanical “section” in place of species groups since there is simply no other option. It’s my understanding that (for inverts at least), complexes serve as a way of grouping together many nearly identical-looking species, while groups are used as more of a form of organisation for breaking down large genera. @hopperdude215 may want to weigh in on this as well.

My understanding is essentially the same as Caleb’s:

Off the top of my head, an example is the subgenus Oncometopia (Oncometopia), which has the species group Oncometopia orbona and the species complex Oncometopia clarior within it. I’ve not yet implemented this taxonomy into iNat (and no need to call O. clarior a complex yet since all children are undescribed and the complex was erected very recently) so it may not be the best example. The most significant (but less complicated) example for leafhoppers on the site is the genus Graphocephala which has three main species groups: Graphocephala, Neokolla, and Hordnia. This is used on BugGuide and is a very different concept from species complexes, at least in terms of arthropods.

It’s worth noting that subgenera, species groups, and species complexes are all different and not interchangeable, at least in terms of leafhoppers, and are all important taxon levels referenced and described in papers and databases. “Section,” while incorrect, is the only taxonomical level that’s capable of substituting species groups and Kyle and I have agreed it seems to be the best option. The inconsistency between BugGuide and iNat due to the lack of species groups here is rather frustrating.

I’ve been wondering if it would be appropriate to make a feature request topic on this or to just shoot an email to staff, but since this thread already exists I’m not sure if that would be necessary/permitted. I hope this is seen so late into the thread. I’d just like to note that this is a very important taxonomical issue in my area of curation though (along with undescribed species and a “_ or _ species” feature, which I may make forum posts about).


This is a rich area of theory and a challenging area of practice in biology. Efforts to find consistent naming conventions have run head on into stubborn inconsistent facts on the ground in every theoretical treatment of taxonomy. The only consistent organizing principle is that nature is inconsistent.

My understanding of the terms species complex and species group is that they are used by some people more or less interchangeably and that where they are used differently complex is more precise (close genetic relationship, very close similarity of appearance). Neither is a formal taxonomic rank. Their utility is a matter of whether they contribute to the organization and analysis of observations in a particular context.
In the context of iNat, it probably does in some cases; the question that curators have to resolve is how much detail is needed to achieve those iNat objectives. If a level of detail is largely of academic interest and not of functional utility in the context of folks with mobile phones taking photographs and recording sounds to post online for aid in identification then we probably don’t need to worry about it and will mostly just complicate life. Where they matter is in the credibility of observations. In some instances it should probably not be possible to ID to species without providing the anatomical evidence and ticking a box that says you collected the necessary data.

The frustrating but interesting truth is that we lack universally applicable definitions for the most basic unit of taxonomy that connect the field to the central theories of biology. Species are slippery things and although humans have a predilection for sorting things into boxes the things we’re sorting don’t always fit their containers very well.


Very true. I do however believe it would benefit iNat to add this if complex and section are already part of the system. I think the same could be said for taxonomy as a whole, honestly. It also helps grant users more specific ID’s than genus-level, which I think we’ve found is much more satisfactory to the userbase. Also, having the option is better than not imo; many of the options apply to some regions of taxonomy and not others. I think we should stick to the taxonomic authorities on iNat and not simplify/reduce things to the point that they are erroneous.

Regarding your point about taxonomy, yes, it’s very much a human construct. Jim addressed some of these things:

I really think we just have to do the best we can in order to understand the world around us and it goes without saying that classification and categorisation is immensely important in science (and can be detrimental when it comes to other things, such as human beings). I believe that iNat should be accurate and precise as it is one of the leading voices for publicly-accessible taxonomy on the web, whether it intends to be or not.


also tagging you here, @tiwane, just in case :P

Fair enough.

I think this conversation serves to clarify how slippery some of these concepts really are and what the challenges are likely to be going forward.

I’m wondering how folks would see this applying to something like the Coregonus artedi complex, which has at various times been referred to as an example of a species flock, incipient species or ecomorphotypes.

EDITED to add: Should have specified that the relevant details for that link are in the About tab, which contains a relatively decent summary of the main points of the discussion.

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One thing worth noting: if the genus only contains a few species, the use of a complex or section seems wholly redundant. The conversation came up regarding Limacus recently, as to whether the two species should be treated under a complex name. However, with only 2 species in the genus, just sticking to genus level seems to be sufficient to avoid redundancy.

As to how this may apply to genera with 3 or 4 species, I’d leave that for discussion. For instance, if a genus has 3 species, and 2 of them are considered part of a “complex”, is there much purpose in creating the complex to cover those 2? Or is genus sufficient in that case? The complex label is more effective in larger genera where highlighting the group of species is useful data-wise.