my understanding is that if you’ve posted an undescribed species, you would just identify it to the nearest existing ancestor taxon or a close species that could constitute a species complex that includes your organism. after the organism is formally described, then you can make the necessary identifications or taxon changes.
if you’re posting a particular individual of an undescribed sex or life stage of an otherwise described species, then i guess no one would be able to base an identification on a scientific description, but it wouldn’t stop anyone technically from identifying your observation in the system anyway.
i’m not aware of any general legal or other issues related to posting before a formal description, but maybe there could be specific situations where it may matter to certain stakeholders.
I’ve done observations of an undescribed slug. Someone who is currently working on them has marked them as being IDed as well as possible at Genus level. I presume after they finish working on the new species, they will come back and ID the observations appropriately.
There is no formal or legal problem for the describer, if already working on describing that species, if a picture appears in the public. They can later publlish a formal description of the species without any issue - and even use that observation and cite it in the article, or use long-time existing herbaria samples and stuff like that.
There can be some danger of being scooped, but these days it is extremely small. Normally there is much more information and work necessary to be able to describe it than one photo anyway, but there can be exceptions (some extremely rarely captured marine animals?).
From a taxonomic viewpoint, you should avoid writing in any future (to be proposed) scientific name (i.e. one yet unpublished) so it cannot be mistaken as intended final version. For example, if a new name combination is given without any companion description then that name can be declared as unacceptable, so set aside as Nomen nudum. There’s plenty of variant alternatives you can do as placeholder such as just putting the unpublished part of the planned name within apostrophes, or avoiding it altogether. Here i’m meaning anything you write yourself as annotation under your observation, or in a comment.
As for an un-described sex of an already validly published species name, then no, there should be no taxonomic issues about using the existing name for it. You might however just get questions about how did you identify it when only the other sex is described!
We had uploaded several observations of Conocephalus cinnamonifrons Braun, 2022 and Anisophya arreguii Delaloye & Braun, 2023, two katydid species from the province of Buenos Aires, before they were described, at that time identified to genus. The iNat observations were mentioned in the corresponding papers. There are numerous observations of undescribed katydid species in Argentina and elsewhere.
https://www.inaturalist.org/observations/3740018 another example that was easy off the top of my head. Specifically, Litylenchus crenatae/Beech Leaf Disease. There are multiple examples of reports of this pathogen on iNat before the cause was officially determined - in a case like this, its probably extremely useful, because you can look back year by year to see the spread of the disease
A name that was originally used as a nomen nudum can be validly published with a code-compliant description, the name isn’t stricken forever. It just runs the (slight) risk of someone else publishing the same name for a different taxon in the meantime, which would cause quite a bit of confusion. OTOH, if you’re sure you’re going to publish it, listing the manuscript name is helpful in keeping track of things.
Its really cool how new/undescribed species can just be hiding under our noses, even in countries with significant research institutions such as the United States. A lot of people believe that in order to discover something new you need to visit remote areas where few people explore, yet often times you can find them in your own backyard. I was walking along a bike path and found a gall that I later learned is an undescribed species.
I don’t know about the process of describing a species, other than I’ve heard its hard and difficult. I wish there was more funding and incentive for researchers to publish and formally describe new species that they uncover so we can better learn and understand their distribution and ecology.
I’ve been dipping my toes into helping with a fungi sequencing project for my state, and even with my very fresh experience and knowledge, I’m just amazed at what comes back as undescribed species - and not just like, new species, but things that people know about, have accepted provisional names, and have multiple sequenced specimans already on iNat, mushroom observer, etc… but there’s just not enough manpower or funding to get things described, or even really go through the genuses that are taxonomical nightmares.
This is really only applicable to Curators (since we can create/change things), but actually ENACTING proposed taxonomic changes or creating a new species based on something that has yet to be published can lead to some major problems. It runs the risk of basically making the to-be-published species’ names and taxonomic changes invalid even before they are published, as they have been done without formal descriptions. It’s not insurmountable, as has been noted, but it should be avoided at all costs for the sake of the taxonomists doing the work. It’s potentially a much bigger issue that writing a proposed name in the comments. I’ve had to be very careful that the results of a soon-to-be published cicada revision aren’t reflected here before it actually comes out.