Neuroanatomy of the complex tibial organ of Stenopelmatus (Orthoptera: Ensifera: Stenopelmatidae)

Publication Type:Journal Article
Year of Publication:2008
Authors:Strauß, Lakes-Harlan
Journal:The Journal of Comparative Neurology
Volume:511
Issue:1
Pagination:81 - 91
Date Published:Jan-11-2008
ISSN:00219967
Keywords:chordotonal organ, Ensifera, neuroanatomy, sensory evolution, Stenopelmatidae, vibrational communication
Abstract:

Stenopelmatidae (or “Jerusalem crickets”) belong to the atympanate Ensifera, lacking hearing organs in the foreleg tibiae. Their phylogenetic position is controversial, either as a taxon in Tettigonioidea or within the clade of Gryllacridoidea. Similarly, the origin of tibial auditory systems in Ensifera is controversial. Therefore, we investigated the neuronal structures of the proximal tibiae of Stenopelmatus spec. with the hypothesis that internal sensory structures are similar to those in tympanate Ensifera. In Stenopelmatus the complex tibial organ consists of three neuronal parts: the subgenual organ, the intermediate organ, and a third part with linearly arranged neurons. This tripartite organization is also found in tympanate Ensifera, verifying our hypothesis. The third part of the sense organ found in Stenopelmatus can be regarded by the criterion of position as homologous to auditory receptors of hearing Tettigonioidea. This crista acustica homolog is found serially in all thoracic leg pairs and contains 20 ± 2 chordotonal neurons in the foreleg. The tibial organ was shown to be responsive to vibration, with a broad threshold of about 0.06 ms−2 in a frequency range from 100–600 Hz. The central projection of tibial sensory neurons terminates into two equally sized lobes in the primary sensory neuropil, the medial ventral association center. The data are discussed comparatively to those of other Ensifera and mapped phylogenetically onto recently proposed phylogenies for Ensifera. The crista acustica homolog could represent a neuronal rudiment of a secondarily reduced ear, but neuronal features are also consistent with an evolutionary preadaptation.

URL:http://doi.wiley.com/10.1002/cne.v511%3A1
DOI:10.1002/cne.v511:110.1002/cne.21836
Short Title:J. Comp. Neurol.
BioAcoustica ID: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith