Organismal forms - who decides, and how, if they are to be added or not to the taxonomy?

I see that organismal forms have made it into iNat’s taxonomy. For example Volucella bombylans has three forms, Argynnis paphia has one, etc. So I guessed if they are part of the taxonomy now - written like “Volucella bombylans f. bombylans” for example - they should be created whenever requested?

But I created a request (flag) about the forms of Nezara viridula ( and there curators are telling me that taxonomists don’t work with forms, etc. But iNat is not just about taxonomy and these are distinct phenotypes that someone (like me) might be interested in. And since they are added into the taxonomy it feels like iNat has made an official statement that they are allowed. Are there any curator guides regarding forms? I’m sure I can find a willing curator to add them but shouldn’t there be a coherent stance about them? Right now Nezara viridula feels jealous of Volucella bombylans…

Reasons for their existence:

  • Users will find a better match for their observations with forms and we’ll get less exclamations like “hey, that doesn’t look like mine”
  • Forms have a biological meaning as distinct phenotypes. Some phenotypes (melanism and other) occur more often in warm times and places and we could check that with iNat’s data. Some phenotypes have different geographic distributions, etc.
  • Identifying to forms is fun :-)

Forms are not available names under the ICZN, so I would think they should not be added to animal taxonomy on iNat. And while not explicitly stated in the curator guide, I get the impression that curators should only be adding clades. I think the rank may exist in our system for plants/fungi which are governed by different taxonomic standards.

You might be interested in some similar comments here:

But all IDs are based on a taxonomic framework. Mixing frameworks seems like a bad idea to me.


If you want to identify/track specific traits, you could always make an Observation Field for that. But if these are just different phenotypes that occur throughout different populations, this seems like it would be the same as arguing that brown, black, orange, and white cats should each get their own form under Felix catus

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So why did Volucella bombylans and others get forms but Nezara viridula and others didn’t? Shouldn’t this be more consistent? There are other nonmonophyletic groupings in iNat like Symphyta, Reptilia, etc. which deviate taxonomy much more than forms. At least forms are confined to the leaves in a tree-like structure which makes them easily integrated into the taxonomy.

If forms exist in the classification, then they should be added upon request. If you think they should not be added, then forms must not exist.

Forms don’t exist in the groups I work with because I’ve gotten rid of them. But I’m not an entomologist, and many curators stretch all sorts of rules. There’s no way to enforce everything. If the community really wanted forms for some reason, I wouldn’t push back too hard for groups I don’t work with. But that should be decided by multiple users. This is also another reason why it’s problematic that there isn’t an overarching external authority for insects.

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I’m more familiar with plants where forms, varieties, etc. all are widely accepted.
So when I saw that on iNaturalist forms were now applicable to insects too (specifically the Harlequin Ladybeetle Harmonia axyridis), I just used them without questioning.

After seeing this post and bit of research, it seems that no “rank” below subspecies (form, variety, etc.) is officially accepted in zoological nomenclature.
However, I feel like that is applied quite inconsistently. For example, I’ve never seen any example where the domestic pigeon wasn’t identified as Columba livia var. domestica (which interestingly is called Columba livia f. domestica on Wikipedia).

Why is it accepted in that case and less so for insects?
And how should I add identifications from now on? Should I stick to species (or subsp.) level IDs for everything zoological, always identify variety or form even when they’re not officially accepted, or do it differently depending on the species?

I think that acceptance of “Columba livia var. domestica” might stem from the fact that it points to a ‘domesticated’ form of the species. Domestic animals often have uncertain status (some authors treat them as subspecies or forms, others as distinct species) but no doubt there is genetic component to the domestication - even if there can be hybrids with ‘wild type’, the domestic animals make a genetically distinct ‘population’. It is not always the case with insects, where there can be colour forms in the same population, like melanistic individuals or spring and summer individuals of Araschnia levana.

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as @justyna_kierat suggests, it is due to the domestication part.
there are rules for botanical cultivar (cultivated variety) nomenclature, but I guess there is no corresponding nomenclatural guidance for the zoological counterpart.

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I’ve had the same challenge with white monarchs.

I appealed to the curators of the taxon but they decided that plants get forms and animals don’t. The workaround was to add an Observational Field, but it’s less than optimal.

White monarchs are exceptionally rare outside of the Hawaiian population (where they’re still outside the norm). I’d like to research their occurence on the mainland; whether or not they occur more frequently in certain locations, during certain seasons, and so forth.

A separate taxon that’d be immediately apparent when observing would be straightforward. There’s almost zero chance that someone would observe one, and then use a observation field consistent with other observers in order to document a viably searchable population of data. Even if somehow everyone named their field “Form”, are they going to enter “Nivosus”? “White”? “Awesomesauce”?

One of iNaturalist’s best features is that taxon are a consistent, closed set which allows selection from a list. But then you have this extra other place hidden off to the side where fields can be added by hand with no enforcement of consistency or standards.

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To me it seems a good case for creating a project. Sure that not everyone will be aware of it and some observations might go unnoticed but IMHO not all users will be also aware of the appropriate taxon available. For example, when I’m identifying, I rather use my knowledge that an organism is a species X, rather than looking into iNat taxonomy which are descendants of this species. I could imagine looking at descendant species when one knows the genus, but not so much looking at lower taxa when one knows the species. And taking into account that these white monarchs are so rare, I suspect that AI will not learn too quick to identify and suggest them to users?


Even if somehow everyone named their field “Form”, are they going to enter “Nivosus”? “White”? “Awesomesauce”?

You can make an Observation Field with a drop-down menu of options. [Edit: I’m assuming you’d probably name it something like “monarch/D. plexippus form”, rather than have one universal “Form” field.]

Even if you don’t want to create your own project, you could add observations (and encourage others to add them) to the Albino, Leucistic, & Melanistic Animals project


I think having forms is quite useful for identification and educational purposes.

When a user looks at pictures of a species and finds countless pictures that look very different from the uncommon form they observed, it can be difficult to understand why people are identifying it as that species.

I’ve seen it happen with organisms that simply vary in color, like Anaxyrus americanus (American toad), where people expect it to be a brown-beige dirt color, but they found one that is grey or pink and don’t understand that it is the same species.
When you look at the vast differences that some insects can display within the same species, having forms available on iNaturalist can help educate people.

I don’t think having forms available for identification goes against the use of the taxonomic framework, it would just be additional information, which can easily be ignored.

It’s not iNat curators that made this decision.

The International Code of Zoological Nomenclature (ICZN) specifically prohibits “infrasubspecific names” including “form”:

The International Code of Nomenclature for algae, fungi, and plants (ICNafp or just ICN) allows a finer hierarchy of ranks below species including “subspecies”, “variety”, “subvariety”, “form” and “subform”:

Either way, ICZN/ICN ranks are generally intended to reflect sustaining populations with discernable perpetuated characters. In the past, some biologists would create names for spontaneously arising characters in individual organisms, but that’s not really what modern taxonomy is intended to address.


Adding forms seems harmless since the people who don’t like them don’t have to use them. Of course they will probably soon all be elevated to species level anyway…

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I on’t think so, because not all forms mean genetically distinct populations. Forms appearing inside one population and able to interbreed without difficulty will never be elevated to status of distinct species.

things are being described as species that aren’t distinct in any way. Taxonomic splitters don’t seem to actually follow the guidelines you mention at all.

OK, I agree that there are might be, let’s say, mistakes in describing species (the famous old ones, like describing two sexes as separate species). But what I meant was that if it is known that there are forms not related to distinct genetic lines - like, melanistic or albino individuals appearing in a population, two generations looking different, they will not be separated into different species - I don’t believe any sensible scientist would do something like that (and any journal would publish), knowing the situation of such morphological forms.

well, i’ve seen a lot of ‘species’ in plants that very readily intergrade. Though to be fair with some taxa like willows and some groups of oaks, if you used this metric you wouldn’t really have species to distinguish at all which is too far towards lumping (yes i think it’s possible to go too far lumping).

But the journal issue is also relevant here. There have been multiple cases of iNat curators adding new species splits from papers that haven’t been peer reviewed yet. I think the peer review process tolerates too much splitting but i also think it’s at least some sort of filter and needs to be used here to say the least. We had one case where the author of an in-progress paper came to iNat to tell someone they shouldn’t have made the change yet (though i would argue they never should period). The change was still made though and the person who made it refuses to undo it so the taxa is still basically broken or was as of last week.

So the idea that we can’t add forms to iNat doesn’t really make much sense given how readily ‘species’ and other things like that are added. I think forms are great. It allows us to track variation without making every tiny thing a new species with all those consequences thereof.

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Could you give examples of such cases in animals? I mean, not of cases where new species is controversial because there is no agreement whether the populations/lines are genetically far enough to be species - I’m first to agree that there are plenty of such examples. But of cases when a form, which is known to be only a morphological form of a species, arising from phenotypic plasticity, mutation, etc, is elevated to the range of species? I’m asking about animals, as it seems that this thread covers them, and in plants things are quite different in some aspects (eg crosses between species are more widespread, and probably there are further differences important to this topic which I’m not even aware of, as a more of a zoologist)

no, because i’m a botanist. It may be that the splitting in animals is justified, i can’t really say.

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