Tactopoda

Tactopoda is a proposed clade of protostome animals that includes the phyla Tardigrada and Euarthropoda, supported by various morphological observations.[1][2]

Tactopoda
The tardigrade Hypsibius dujardini
The blue crab Callinectes sapidus, an arthropod
Scientific classification
Kingdom:	Animalia
Subkingdom:	Eumetazoa
Clade:	ParaHoxozoa
Clade:	Bilateria
Clade:	Nephrozoa
(unranked):	Protostomia
Superphylum:	Ecdysozoa
(unranked):	Panarthropoda
(unranked):	Tactopoda Budd, 2001 [1]

The competing hypothesis is Arthropoda (= Euarthropoda + Onychophora)[3]

Classification

• Phylum Tardigrada
  • Class Eutardigrada
  • Class Heterotardigrada
  • Class Mesotardigrada
• Phylum Arthropoda
  • Class Pycnogonida (?)
  • Clade Arachnomorpha
    • Class †Trilobita
    • Order †Aglaspida
    • Order †Strabopida
    • Class Pycnogonida (?)
    • Order †Cheloniellida
    • Subphylum Chelicerata
      • Class Xiphosura
      • Class †Eurypterida
      • Class †Chasmataspidida
      • Class Pycnogonida (?)
      • Class Arachnida
  • Clade Mandibulata
    • Order †Euthycarcinoidea
    • Subphylum Myriapoda
      • Class Chilopoda
      • Class Symphyla
      • Class Diplopoda
      • Class Pauropoda
    • Clade Pancrustacea
      • Clade Oligostraca
        • Class Ostracoda
        • Some of polyphyletic class Maxillopoda
      • Clade Altocrustacea
        • Clade Multicrustacea
          • The rest of polyphyletic class Maxillopoda
          • Class Malacostraca
        • Clade Allotriocarida
          • Class Branchiopoda
          • Clade Miracrustacea
            • Superclass Xenocarida
              • Class Cephalocarida
              • Class Remipedia
            • Subphylum Hexapoda
              • Paraphyletic class Entognatha
              • Clade Ectognatha
                • Class Insecta

Phylogeny

Panarthropoda

Velvet worms (Onychophora)   Tactopoda Tardigrada   Eutardigrada     Heterotardigrada     Mesotardigrada     Arthropoda   †Trilobitomorpha/Trilobita     ?Pycnogonida   Chelicerata   Xiphosura         †Eurypterida     †Chasmataspidida         Arachnida     ?Pycnogonida         Mandibulata Myriapoda   Symphyla     Chilopoda       Diplopoda     Pauropoda       Pancrustacea Oligostraca   Ostracoda     Some of Maxillopoda     Altocrustacea Multicrustacea   The rest of Maxillopoda     Malacostraca     Allotriocarida Xenocarida   Remipedia     Cephalocarida       Branchiopoda   Hexapoda Ellipura   Collembola     Protura       ?Diplura       ?Diplura   Ectognatha   Insecta

References

1. Graham E. Budd (2001). "Tardigrades as 'stem-group arthropods': the evidence from the Cambrian fauna" (PDF). Zoologischer Anzeiger. 240 (3–4): 265–279. doi:10.1078/0044-5231-00034. Archived from the original (PDF) on 2016-03-03.
2. Smith, M. R.; Ortega Hernández, J. (2014). "Hallucigenia's onychophoran-like claws and the case for Tactopoda". Nature. 514 (7522): 363–366. doi:10.1038/nature13576. PMID 25132546.
3. J. Ortega-Hernández, "Making sense of 'lower' and 'upper' stem-group Euarthropoda, with comments on the strict use of the name Arthropoda von Siebold, 1848," Biol. Rev., vol. 91, no. 1, pp. 255–273, 2016.