Arthropod taxonomy

thumb| Pancrustacea is the clade that comprises all crustaceans and all hexapods (insects and relatives). This grouping is contrary to the Atelocerata hypothesis, in which Hexapoda and Myriapoda are sister taxa, and Crustacea are only more distantly related. As of 2010, the Pancrustacea taxon was considered well accepted, with most studies recovering Hexapoda within Crustacea. The clade has also been called Tetraconata, referring to having a four-part cone in the ommatidium. The term "Tetraconata" is preferred by some scientists in order to avoid confusion with the use of "pan-" to indicate a

The clade Mandibulata constitutes one of the major subdivisions of the phylum Arthropoda, alongside Chelicerata. Mandibulates include the myriapods (centipedes and millipedes, among others), and the pancrustaceans (including all true insects). The name "Mandibulata" refers to the mandibles, a modified pair of limbs used in food processing, the presence of which are characteristic of most members of the group.

Arachnomorpha is a proposed subdivision or clade of Arthropoda, comprising the group formed by the trilobites and their close relatives (Artiopoda), Megacheira (which may be paraphyletic) and chelicerates. Under this proposed classification scheme, Arachnomorpha is considered the sister group to Mandibulata (including insects, crustaceans and myriapods).

Atelocerata is a proposed clade of arthropods that includes Hexapoda (insects and a few related taxa) and Myriapoda (millipedes, centipedes, and similar taxa), but excludes Crustacea (such as shrimp and lobsters) and Chelicerata (such as spiders and horseshoe crabs). The name is currently used interchangeably with Tracheata. or Uniramia sensu stricto. It is an extensive division of arthropods comprising all those that breathe by tracheae, as distinguished from Crustacea, which breathe by means of gills.

thumb|left|As members of Myriapoda, centipedes like this [[Scolopendra polymorpha are part of subphylum Uniramia]] Uniramia (uni – one, ramus – branch, i.e. single-branches) is formerly recognised group within Arthropoda, now recognised as non-monophyletic, united by their strictly uniramous (single branched) appendages. thumb|left|Onychophora like this Peripatoides sp. are no longer counted as unirames.

Deuteropoda is a proposed clade of arthropods whose members are distinguished from more basal stem-group arthropods like radiodonts by an anatomical reorganization of the head region, namely the appearance of a differentiated first appendage pair (the 'deutocerebral' pair), a multisegmented head, a hypostome/labrum complex, and by bearing pairs of segmented biramous (two branched) limbs.