Pancrustacea over Hexapoda and Crustacea

Why do you think that Crustacea and Hexapoda are used instead of Pancrustacea. I think that Pancrustacea better represents the relationship between the two groups which seems to be a major aspect of taxonomy. If it’s just due to the group not being accepted yet, do you think it should be?

Are you referring specifically to iNat’s handling of these taxa? Or is it a more general question?

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changes to the base of the tree that impact 10s of millions of down stream observations (e.g. 42M hexapod observations) put a load on the site that we’re currently not well equipped to handle.

While our taxonomic reference for animal phyla (WoRMs) now considers Insects to be Crustacea, we’re deviating for the foreseeable future until we can address the above mentioned concerns

While many have expressed frustration over parts of the base of the iNat tree that aren’t monophyletic (e.g. Dicots, Reptiles etc.), since those nodes at the base of the tree are rarely the final destination for observation IDs it doesn’t have a huge impact on Identifications

With regards to searching/filtering obs, you can enter multiple taxa into the explore URL to simulate these missing nodes, e.g. here’s one for Crustacea and Hexapods that could be used to simulate Crustacea sensu WoRMs (e.g. Pancrustacea),85493&view=species


I just mean in general.

Whilst Hexapoda sit inside Crustacea (known since 2011 or so), I don’t think one should rename Crustacea into Pancrustacea. The former name doesn’t lose validity. The technical question concerning Inat has already been answered, I believe for the same reason birds won’t be included into reptiles anytime soon (and I hope nobody proposes to rename them into something like Avereptilia).

See also

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I actually didn’t know that it was accepted by any taxonomy! As for iNaturalist I get that it would be a difficult thing to do. Is there any sort of plan so to how to implement such a change?

I kind of overlooked the naming, and I definitely agree with you on that, although I would say that if it’s possibly for the hexapods to be moved into Crustacea, then it should be done. While I don’t know as much with the birds and reptiles, that does seem like something that should be kept separate, and that seems to be how the taxonomy is general done. It would also create a bigger issue revolving Amphibians, and then a class of fish, so with the Vertebrates, the classes should be kept separate.

There are two approaches to cope with things being found to be nested in other clades.

One is to split the larger group in several smaller ones until each of them isn’t paraphyletic anymore. This is easy when the relatives of the ancestors of the smaller group are all extinct, e.g. with Amphibia: They consist (according to some theories, the topic seems to be in motion, I follow wikipedia here) of Leptospondyli (extinct, probably ancestors of Amniota), Temnospondyli (extinct) and Lissamphibia (contains all living ones); i.e. there are no living amphibians which are related to us.

Another example is dicots: monocots are descendants from some of them, and APG4 took care of splitting dicots finely enough to have monocots as sister group to some other branch and everything is sorted nicely, see Cladogram 1 in or . “Dicots” is essentially gone, we have eudicots that sit besides monocots and several other groups (all having two embryonal leaves) which split off below the clade formed by monocots+eudicots.

That approach is hard to implement when the small group is nested very deeply inside the larger one, e.g. with hexapods inside crustaceans. In that case the large group would have to be pulverized beyond recognition (hexapods sit somewhere near waterfleas or remipedia), see image (part of the open-access paper ). In that situation, it is more convenient to accept that insects are crustaceans.

Living reptiles would have to be dissolved into (i.e. replaced by) crocs+birds+tuatara (one species)+Squamata. I could live with that, but I like the inclusion of birds into reptiles more.

I think with the birds and reptiles it just feels nice (when forced to choose between the two options) to group in birds, to destroy Reptilia just to not include birds seems counterintuitive, because instead of simplifying things while also keeping them monophyletic, it just leads to the fairly simple to understand group Reptilia, becoming more complicated in a sense.

For me, personally, insects being classified as Crustaceans seems to be a great solution. Partly because it would make insects seem more like “actual animals” to more people. And of course it reflects their evolution much more correctly. And that’s something that about a year ago I really started to get interested in, the early evolution of the insects, and their close position to crabs and lobsters, and of course to a much greater extent, fairy shrimp, should be something that becomes more widely known. Like I said earlier about the insects being animals, it’s something that I would love to see for more people to learn, and even just that information becoming more widespread could potentially help with their conservation.

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