Comparative Morphology of Central Neuropils in the Brain of Arthropods and Its Evolutionary and Functional Implications
Most insects and decapod crustaceans possess an assemblage of midline neuropils, the central complex. Recent phylogenetic studies show a sister-group relationship between hexapods and decapods, suggesting that central complexes in both groups are homologous structures derived from a basal ancestral neuropil . This ancestral archetype of the central complex (lacking the protocerebral bridge) might be represented in the chilopods. Until recently, diplopods were regarded as closely related to chilopods and united within the taxon Myriapoda. The entire lack of a midline neuropil in diplopods, however, renders the monophyletic origin of the class Myriapoda unlikely . In this study we used a palette of immunocytochemical and neuroanatomical methods to investigate mid-line neuropils in hitherto poorly examined arthropod groups. Of special interest for resolving arthropod phylogeny are onychophorans, who are believed to be an evolutionary ancient group that resembles the ancestors of modern arthropods. Striking similarities in central brain neuroarchitecture of the onychophoran Euperipatoides rowellii and of a chelicerate species, however, suggest a close phylogenetic relationship between these two groups. Our findings imply that onychophorans either represent the oldest form of the chelicerates or that extant onychophorans have developed from chelicerate-like ancestors by neoteny.
KeywordsCentral complex immunocytochemistry neuroanatomy Onychophora locomotor control
Unable to display preview. Download preview PDF.
- 3.Bordeaux, H. B. (1979) Arthropod Phylogeny with Special Reference to Insects. Wiley, New York.Google Scholar
- 4.Brusca, R. C., Brusca, G. J. (1990) Invertebrates. Sinauer, Sunderland.Google Scholar
- 8.Fl gel, J. H. L. (1878) ber den einheitlichen Bau des Gehirns in den verschiedenen Insektenordnungen. Z. Wiss. Zool. 30 (supplement), 556–592.Google Scholar
- 11.Holmgren, N. (1916) Zur vergleichenden Anatomie des Gehirns von Polychaeten, Onychophoren, Xiphosuren, Arachniden, Crustaceen, Myriapoden und Insekten. K. Svenska Vetensk. Akad. Handl. 56, 1–303.Google Scholar
- 14.Ioffe, I. D. (1963) Structure of the brain of Dermacentor pictus Herm. (Chelicerata, Acarina). Zool. Zh. 42, 1472–1484.Google Scholar
- 23.Strausfeld, N. J. (1999) A brain region in insects that supervises walking. Progr. Brain Res. 123, 273 284.Google Scholar
- 27.Strauss, R., Trinath, T. (1996) Is walking in a straight line controlled by the central complex? Evidence from a new Drosophila mutant. In: Elsner, N., Schnitzler, U. (eds), Proceedings of the 24th G ttingen Neurobiology Conference. Vol II. Thieme, Stuttgart, p. 135.Google Scholar
- 33.Williams, J. L. D. (1975) Anatomical studies of the insect central nervous system: A ground-plan of the midbrain and an introduction to the central complex in the locust Schistocerca gregaria (Orthoptera). J. Zool. 176, 67–86.Google Scholar
This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.