Skip to main content
Figure 2 | BMC Evolutionary Biology

Figure 2

From: Immunolocalization of serotonin in Onychophora argues against segmental ganglia being an ancestral feature of arthropods

Figure 2

Two competing hypotheses on phylogenetic position of arthropods and their bearing on the evolution of segmental ganglia. (A) Articulata hypothesis: Arthropoda and Annelida are sistergroups. Segmental ganglia represent one of the synapomorphies uniting these taxa, but must have been reduced in Onychophora and modified in some annelids. (B) Ecdysozoa hypothesis: Arthropoda and Cycloneuralia (nematodes, priapulids, and allies) are sistergroups. Segmental ganglia evolved within the Arthropoda after the separation of Onychophora from the remaining arthropod groups.

Back to article page

BMC Ecology and Evolution

ISSN: 2730-7182

Contact us