Add subphyla to Arthropoda

[camiplata]

As far as I understand the sources containing the classes under Myriapoda, also use Myriapoda as a subphylum.

[DaveNicolson]

Dividing Arthropoda into 4 subphyla (Chelicerata, Crustacea, Hexapoda and Myriapoda) is a useful way to organize the classes, although there may be cladistic reasons against it (not sure how "Pancrustacea" and some other groups are being handled recently). But it is certainly worth considering using Myriapoda as a subphylum for classes Chilopoda, Diplopoda, Pauropoda and Symphyla.

[DianRHR]

Actually there are no subphyla at all in Arthropoda, for example, Crustacea is also not included in the catalog despite its practical use and that it is considered in WoRMS. Regarding Pancrustacea, as it is a clade, it might not be considered soon in the higher classification, there are several phylogenomic analyses that show its lack of stability. It's also considered now as 'synonym' of Crustacea in WoRMS

[mdoering]

I am in favor of following Ruggiero and use the 4 subphyla @DaveNicolson mentioned: https://www.checklistbank.org/dataset/294066/classification?taxonKey=An%3A673

... plus Artiopoda for Trilobites.

[yroskov]

Can we pass this to Taxonomy Group, please (@dhobern)

[mdoering]

A general question - @dhobern should we pass all changes in the hierarchy to the TG or can editors simply apply changes when they work towards the hierarchy given by Ruggiero et al.? I slightly fear we become slow and the TG overloaded, especially now that we probably have to fill lots of gaps for the extended release until summer...

[DaveNicolson]

We made some advances beyond Ruggiero et al. (2015) in ITIS, particularly for subphylum Chelicerata... We ended up with this: [SUBSEQUENTLY WE ADJUSTED FURTHER TO drop Euchelicerata (still valuable, but forces rank shifts that Dr. Zhang did not favor), shift rank of Arachnida back to full class, shift "subclass Xiphosura" to Class Merostomata with order Xiphosura, move Opilioacarida into Parasitiformes (dropping Opilioacariformes)... Sorry for the confusion, but most of those late shifts were strongly recommended by Dr. Zhang.] Subphylum: Chelicerata ..Class: Euchelicerata ....Subclass: Arachnida ........Order: Amblypygi (no superorder) ........Order: Araneae (no superorder) ........Order: Opiliones (no superorder) ........Order: Palpigradi (no superorder) ........Order: Pseudoscorpiones (no superorder) ........Order: Ricinulei (no superorder) ........Order: Schizomida (no superorder) ........Order: Scorpiones (no superorder) ........Order: Solifugae (no superorder) ........Order: Uropygi (no superorder) ......Superorder: Acariformes ........Order: Sarcoptiformes ........Order: Trombidiformes ......Superorder: Opilioacariformes ........Order: Opilioacarida ......Superorder: Parasitiformes ........Order: Holothyrida ........Order: Ixodida ........Order: Mesostigmata ....Subclass: Xiphosura ........Order: Xiphosurida ..Class: Pycnogonida ........Order: Pantopoda

[dhobern]

Thanks, @DaveNicolson - that looks promising to me. In answer to the question from @mdoering, we should probably run such changes through the TG, although we need to streamline them compared to the neverending discussions we normally get on this topic. I'll add this to the next agenda and suggest we make it a simple question of "Is this better than we have now?"

[camiplata]

Hi @DaveNicolson I was reviewing the Chelicerata classification for the xrelease and noticed that ITIS website indicates that " ITIS is reverting to using Arachnida and Merostomata as full classes, instead of subclasses of class Euchelicerata"

So I wanted to check with you if what is stated on the website is the latest the decision or is it rather to keep "Euchelicerata".

[DaveNicolson]

Yes, the change was made and the comment notes it.

[DaveNicolson]

Sorry that the "final" hierarchy I posted above was not in fact final... But having shared it and listened to feedback from Dr. Zhang and others, additional changes were made (as found in ITIS now).

[DaveNicolson]

Here's what we ended up with after all the tweaks: Subphylum Chelicerata ..Class Arachnida ......Order Amblypygi ......Order Araneae ......Order Opiliones ......Order Palpigradi ......Order Pseudoscorpiones ......Order Ricinulei ......Order Schizomida ......Order Scorpiones ......Order Solifugae ......Order Uropygi ....Superorder Acariformes ......Order Sarcoptiformes ......Order Trombidiformes ....Superorder Parasitiformes ......Order Holothyrida ......Order Ixodida ......Order Mesostigmata ......Order Opilioacarida ..Class Merostomata ....Order Xiphosura ..Class Pycnogonida ....Order Pantopoda

[camiplata]

Thanks @DaveNicolson!