Arthropod phylogeny: Onychophoran brain organization suggests an archaic relationship with a chelicerate stem lineage

Nicholas J. Strausfeld, Camilla Mok Strausfeld, Rudi Loesel, David Rowell, Sally Stowe

Research output: Contribution to journalArticlepeer-review

104 Scopus citations


Neuroanatomical studies have demonstrated that the architecture and organization among neuropils are highly conserved within any order of arthropods. The shapes of nerve cells and their neuropilar arrangements provide robust characters for phylogenetic analyses. Such analyses so far have agreed with molecular phylogenies in demonstrating that entomostracans + malacostracans belong to a clade (Tetraconata) that includes the hexapods. However, relationships among what are considered to be paraphyletic groups or among the stem arthropods have not yet been satisfactorily resolved. The present parsimony analyses of independent neuroarchitectural characters from 27 arthropods and lobopods demonstrate relationships that are congruent with phylogenies derived from molecular studies, except for the status of the Onychophora. The present account describes the brain of the onychophoran Euperipatoides rowelli, demonstrating that the structure and arrangements of its neurons, cerebral neuropils and sensory centres are distinct from arrangements in the brains of mandibulates. Neuroanatomical evidence suggests that the organization of the onychophoran brain is similar to that of the brains of chelicerates.

Original languageEnglish (US)
Pages (from-to)1857-1866
Number of pages10
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1596
StatePublished - 2006


  • Arthropod evolution
  • Brain organization
  • Chelicerata
  • Onychophora

ASJC Scopus subject areas

  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)


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