Setting up the table has already caused one fair comment to be raised about what happens to the taxon Uniramia. My visits to various sites on the Net has taught me that the situation about the higher classification of the arthropods is chaotic. Valid arguments could be made for any of many of these schemes. The disturbing thing is that many of these different schemes appear on "dot edu" where they are presented as a professor's gospel to his class.
I've probably already left the impression that, right or wrong, I have a preference to the ITIS scheme, and by extension (since ITIS is focused on North America) looking at the "Species 2000" where applicable. I tend to use these on a "without prejudice" basis that recognizes the difficulties inherent in having bureaucrats control the science. This view treats ITIS as a reference point, and nothing more. If a person B's particular scheme differs from ITIS in a defined way it is 1 generation removed from ITIS. A similar situation applies if C's scheme differs in defined way from ITIS. However, if C defines his scheme with reference to B's then he is 2 generations removed from the reference point. String a few schemes in a row, and you begin to lose perspective on the subject.
Cladists have a stated vision of some day being rid of Linnean ranks altogether. Given the uncertainty that often arises from guessing whether a particular taxon is a class or an order, I can sympathize with that view. But without ranks the cladist's tree sometimes lacks good climbing branches where you can place your feet as you go up.
I think that if we can maintain some consistency in using the primary KPCOFGS rankings, we can have more flexibility with the secondary rankings. There is already some degree of acceptance that in most cases only primary ranks will appear in what was the "Placement" list, and what is now the top part of the tables. That doesn't mean that there can be no exceptions to this rule. (Cf. Wikipedia:Ignore all rules)
So, to get back on topic, higher arthropod classification is confused! But there remains that if we want anything about the subject on Wikipedia, we absolutely need to deal with the confusion. Here then is where I see things as standing between phylum and class in the Arthropoda:
- The trilobites (not listed in ITIS) are a phylum with a single class, and that fact appears generally accepted - no problem.
- Chelicerata seems to be the generally accepted name for that sub-phylum; there may very well have been some reason to distinguish this term from Chelliceriformes in the past, but those reasons seem to be fading.
- I have yet to examine issues in the Crustacea, but at least there appears to be general acceptance that is is properly a subphylum.
- In text of the article as it has been the Hexapoda has been treated as a class in Uniramia equivalent with the each of the four classes in Myriapoda. Myriapoda was nowhere to be seen; I was ready to throw out Uniramia (not in ITIS) while restoring Myriapoda. Some of the sites that I have seen which treat Uniramia as a subphyllum also show it as containing two Superclasses: Myriapoda and Hexapoda. This may present the most workable solution to this problem because it allows Insecta to remain as a class.
- ITIS does not assign a class to the three primitive hexapod orders. We can leave it like that or we can apply a class name from another source. In the latter case some sites have opted for a separate class name for each, some have used Endognatha for all three together, and one has limited Endognatha to the Diplura while assigning the class name Parainsecta to the combined Collembola and Protura. I'm open on this point but will leave it as is in the absence of arguments. Eclecticology, Tuesday, July 16, 2002