Is the evolution of arthropod brains convergent?

SummaryWithin the nervous systems of different arthropod groups, homologous neurons were identified that show high degrees of structural invariances. Analyses of the development and the projection patterns of such homologous neurons established criteria by which neuropil areas of different species within arthropod groups like insects or arachnids can be homologized.Such a comparison of principle brain organizations is extended to include species of different arthropod subphyla. It is shown that main central brain neuropil areas such as the central body and the corpora pedunculata, formerly seen as common characteristics of all arthropod groups, are non-homologous in Chelicerata and Mandibulata. Consequently, the central brains of these two arthropod subphyla have to be regarded as the outcome of convergent developments.