What to do with IDs when a taxon is no longer accepted?

[ralfmuschall]

I just ran into a question when doing coarse IDs: I’ve ID’d 8 things as Acari. Now I learned that Acari doesn’t exist (mites and ticks are unrelated, see my comment in https://www.inaturalist.org/observations/164223911).

Is there a recommended way of caring about this? Except for the one mentioned I don’t feel confident to sort them out. What will happen once Inat follows the official taxonomy and destroys Acari, will all IDs fall back to Arachnida? There are 21k obs at level “subclass Acari” https://www.inaturalist.org/observations?hrank=subclass&lrank=subclass&taxon_id=52788

Thinking more about this it seems that the same problem might also occur on finer taxonomic levels.

[DianaStuder]

That would be a discussion to run at the taxon page. I don’t see it mentioned there yet.

[bouteloua]

@ralfmuschall

Is there a recommended way of caring about this?

If there is a taxonomic adjustment that needs to be made, go to the taxon page and select Curation>Flag for curation. If the decision of the flag is to inactivate Acari, it will be done via a taxon change which will automatically update all your past IDs to whatever taxon the group decides is appropriate (e.g. arachnids).

Edit (moved this to its own topic).

[ralfmuschall]

I’m hesitating to do this. If it were implemented, 21k Acari (the only subclass of Arachnida) observations would fall down into “Arachnida” (which has 5k (most of which are Araneomorphae that I’m just beginning to review) at class level, 239k including order level and 6.1M total). I.e. class Arachnida would explode from 5k to 27k, creating a big mess for everybody wanting to ID them.

Maybe shove them into a project first so people who know these animals can find them (similar to my “Larvae of Endopterygota” which sadly nobody but me and one other person uses)?

In addition, the whole Arachnida tree might require reforming, and I don’t feel educated enough to propose the new shape. And I think it is e.g. still unclear whether horseshoe crabs are inside Arachnida of only Chelicerata (there were some genetic papers during the last few years).

[ralfmuschall]

I was thinking a bit more about wishing for respecting taxonomy changes by Inat, and I think the results are mixed (taking into account that the effort of implementing such changes was reported to be rather large):

• Endopterygota would be very useful because all those “worms” could be put there, as well as low-qualitiy images of adult animals that might be bees or bombylids, or wasps/syrphids;
• removing Acari might be harmful as mentioned previously, I’d prefer to see them sorted out before (which is probably hard - if one easily could tell ticks from mites by looking at them mankind would have known they aren’t related before DNA sequencing);
• inserting infraorders Caniformia and Feliformia would allow people to put dog-shaped or bear-shaped animals into a finer group than Carnivora;
• I don’t know if we want Toxicofera (the only situation where this would help is for blurry “snakes” that might be slowworms, but then they might also be Dibamidae or Amphisbaenia), so probably not

Then one has to be careful not to follow new discoveries too rapidly (remember the famous discussion about "the guinea pig is not a rodent"of the nineties).

[AdamWargon]

@ralfmuschall

Now I learned that Acari doesn’t exist (mites and ticks are unrelated, see my comment in https://www.inaturalist.org/observations/164223911).

Ralf, you reminded me of this quote by @matthew_connors:

@matthew_connors

I guess it depends how in-depth you want to go! The more you look at different types of organisms, the more you start finding out weird things about what is and isn’t related. Here are just a few examples that I can think of:

The slow worm, sometimes called a deaf adder or a blind worm, is neither a worm nor a snake, but a type of legless lizard. But snakes themselves are actually a type of legless lizard as well! The extinct mosasaurs were also a specialised type of lizard, but New Zealand’s tuatara is not a lizard at all despite looking very much like one.

The killer whale is a species of dolphin, but all dolphins are themselves a type of whale, so that one’s not really a big deal.

The sawshark is a type of shark, but the very similar sawfish is instead a ray despite looking very much like a shark.

Termites look very much like ants and are sometimes called ‘white ants’, but they are not closely related, and in fact termites are a type of cockroach, whereas ants (and bees as well) are a type of wasp!

Similarly, aphids are sometimes called ‘greenflies’, but they are not a type of fly at all - and neither are dragonflies, butterflies, sawflies, or mayflies.

And oddly enough, insects themselves are actually a type of crustacean! Within crustaceans there are many crazy things that don’t make sense - e.g. hermit crabs are not actually a type of true crab, and mantis shrimp are definitely not shrimp!

Caecilians look rather like large earthworms, or perhaps an odd snake, but they are actually amphibians. Blind snakes are also often mistaken for worms, but they are indeed snakes as the name suggests.

Some animals, like corals or sponges, may be mistaken for plants or for each other, but of course they are animals and they are not very closely-related to each other either.

Eels and sea snakes may easily be confused for each other, and there are many different types of fish that have taken on an eel-like body but are not closely related.

As well as harvestmen like you mentioned, there are also many different arachnid groups that might be mistaken for spiders and scorpions - vinegaroons, amblypygids, solifuges, schizomids, and even non-arachnids like sea spiders, bat flies, some crabs, and mimics like the spiny leaf insect.

Jellyfish, comb jellies, and salps look very similar to each other, but none of them are closely-related at all.

Eagles, hawks, and kites are all closely-related, but falcons are completely different, as are owls and their unrelated lookalikes, frogmouths.

Worms are probably the worst of them all! Earthworms, tapeworms, ribbon worms, peanut worms, nematode worms, acorn worms, ship worms, penis worms (yes really!), acoel worms, tongue worms, thorny-headed worms, horsehair worms, horseshoe worms, slow worms, jaw worms, arrow worms, and velvet worms are all in completely different phyla, so they are about as distantly-related as it is possible to get within the animal kingdom!

[matthew_connors]

As far as I’m aware it’s still very much uncertain whether or not Acari is monophyletic or not. Until we have strong evidence that it isn’t and this is widely-accepted, I don’t think we should even be considering splitting it because of all the issues you’ve brought up!

[sjl197]

Discussion about the monophyly of Acari has been going for decades in the literature. However, how these should be (re)grouped relative to other order of arachnids, even as hinted at, the wider uncertainty about definition of Arachnida vs. Chelicerata is also ongoing.

For a practical basis - i’ve no problem with iNaturalist and other sites maintaining some higher groupings that don’t fit with recent shifts in favoured taxonomy, sometimes a ‘classical’ group better suits usage, here allowing users to rule out other orders (of chelicerates, arachnids or beyond). Well, in general, the Chelicerate tree on here might be due for an overhaul, but from the disagreement across recent papers i’m not yet convinced that now is the time for it. Practically, if Acari were to go, then i’d suspect the vast majority unsorted to “Acari” could become respecified as Acariformes, but i’d not want to see anything implemented without at least first making a call to the community to help sort observations into either one of the two major lineages, then at some later stage for the changes to be managed by involvement of experienced curator or even staff. As an aside, it’s wrong to say they’re unrelated - all of the different taxa mentioned throughout this entire discussion are related.

[ralfmuschall]

I totally agree, that’s why I didn’t request a taxonomy change. I don’t think we should spend too much time following recent discoveries (which might even be in error). The only clade I really miss is Endopterygota because it contains visually similar animals that have larvae, so entemologists might set a filter on that and IF them. Currently I have to put “worms” into pterygota and into the project “Larvae of Endopterygota” because for general flying insects Inat correctly doesn’t offer the larval stage of life.