02447nas a2200229 4500008004100000022001300041245010900054210006900163260001600232300001200248490000800260520173000268653002201998653001302020653001702033653002202050653002002072653003002092100002202122700002702144856004602171 2008 eng d a0021996700aNeuroanatomy of the complex tibial organ of Stenopelmatus (Orthoptera: Ensifera: Stenopelmatidae)0 aNeuroanatomy of the complex tibial organ of iStenopelmatusi Orth cJan-11-2008 a81 - 910 v5113 a

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.

10achordotonal organ10aEnsifera10aneuroanatomy10asensory evolution10aStenopelmatidae10avibrational communication1 aStrauß, Johannes1 aLakes-Harlan, Reinhard uhttp://doi.wiley.com/10.1002/cne.v511%3A102840nas a2200241 4500008004100000022001400041245020100055210006900256260001600325300001400341490000700355520200100362653002102363653002002384653001302404653001902417653001802436653001702454653003002471100002202501700002702523856004802550 2008 eng d a0006-897700aNeuroanatomy and Physiology of the Complex Tibial Organ of an Atympanate Ensiferan, Ametrus tibialis (Brunner von Wattenwyl, 1888) (Gryllacrididae, Orthoptera) and Evolutionary Implications0 aNeuroanatomy and Physiology of the Complex Tibial Organ of an At cJan-01-2008 a167 - 1800 v713 a

We investigated the neuroanatomy and physiology of the complex tibial organ of an atympanate ensiferan, the Gryllacridid Ametrus tibialis. This represents the first analysis of internal mechanoceptors in Gryllacridids. The complex tibial organ is tripartite consisting of a subgenual organ, intermediate organ and a homologue organ to the crista acustica of tympanate ensiferan taxa of Tettigoniidae, Haglidae, and Anostostomatidae. The crista homologue contains 23 ± 2 receptor neurons in the foreleg. It is associated with the leg trachea and found serially in all three thoracic leg pairs. Central projections of the sensory nerve of the complex tibial organ bifurcate in two lobes in the prothoracic ganglion, which do not reach the midline. The axonal endings project into the mVAC, the main vibratory-auditory neuropile of Ensifera. Recordings of the tibial nerve show that the tibial organ is sensitive to vibrational stimuli with a minimum threshold of 0.02 to 0.05 ms–2 at 200–500 Hz, but rather insensitive to airborne sound. The main function of the tibial organ is therefore vibration sensing, although the specific function of the crista homologue remains unclear. The presence of the crista acustica homologue is interpreted in phylogenetic context. Because ensiferan phylogeny is unresolved, two alternative scenarios can be deduced: (a) the crista homologue is a precursor structure which was co-opted as an auditory system and represent a morphologically highly specialized structure before acquisition of its new function; (b) a previously functional tibial ear is evolutionary reduced but the neuronal structures are maintained. Based on comparison of neuroanatomical details, the crista acustica homologue of A. tibialis could present the neuronal complement of an ear evolutionary precursor structure, which was successively made sensitive to airborne sound by elaboration of cuticular tympana, auditory spiracle and trachea for sound propagation.

10aAmetrus tibialis10aauditory system10aEnsifera10aGryllacrididae10ahearing organ10aneuroanatomy10avibrational communication1 aStrauß, Johannes1 aLakes-Harlan, Reinhard uhttp://www.karger.com/doi/10.1159/000114405